target sdk 35

Used separate threads for reading and writing, enhancing concurrency and performance.

Note: before was possible to start `SerialInputOutputManager` with `Executors.newSingleThreadExecutor().submit(ioManager)`. Now you have to use `ioManager.start()`

.github/workflows/build.yml

@@ -8,11 +8,10 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v2
-    - name: set up JDK 1.11
-      uses: actions/setup-java@v2
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: 'temurin'
-        java-version: '11'
+        java-version: '17'
     - name: Build with Gradle
       run: ./gradlew assembleDebug

.idea/.gitignore

@@ -3,4 +3,7 @@ codeStyles
 libraries
 workspace.xml
 androidTestResultsUserPreferences.xml
+appInsightsSettings.xml
 deploymentTargetDropDown.xml
+deploymentTargetSelector.xml
+other.xml

.idea/AndroidProjectSystem.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="AndroidProjectSystem">
+    <option name="providerId" value="com.android.tools.idea.GradleProjectSystem" />
+  </component>
+</project>

.idea/compiler.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="11" />
+    <bytecodeTargetLevel target="21" />
   </component>
 </project>

.idea/misc.xml

@@ -6,7 +6,7 @@
     <option name="myDefaultNotNull" value="androidx.annotation.NonNull" />
     <option name="myNullables">
       <value>
-        <list size="15">
+        <list size="18">
           <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.Nullable" />
           <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nullable" />
           <item index="2" class="java.lang.String" itemvalue="javax.annotation.CheckForNull" />
@@ -22,12 +22,15 @@
           <item index="12" class="java.lang.String" itemvalue="org.eclipse.jdt.annotation.Nullable" />
           <item index="13" class="java.lang.String" itemvalue="io.reactivex.annotations.Nullable" />
           <item index="14" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.Nullable" />
+          <item index="15" class="java.lang.String" itemvalue="org.jspecify.nullness.Nullable" />
+          <item index="16" class="java.lang.String" itemvalue="jakarta.annotation.Nullable" />
+          <item index="17" class="java.lang.String" itemvalue="org.jspecify.annotations.Nullable" />
         </list>
       </value>
     </option>
     <option name="myNotNulls">
       <value>
-        <list size="14">
+        <list size="17">
           <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
           <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />
           <item index="2" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.NonNull" />
@@ -42,11 +45,14 @@
           <item index="11" class="java.lang.String" itemvalue="org.eclipse.jdt.annotation.NonNull" />
           <item index="12" class="java.lang.String" itemvalue="io.reactivex.annotations.NonNull" />
           <item index="13" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.NonNull" />
+          <item index="14" class="java.lang.String" itemvalue="jakarta.annotation.Nonnull" />
+          <item index="15" class="java.lang.String" itemvalue="org.jspecify.nullness.NonNull" />
+          <item index="16" class="java.lang.String" itemvalue="org.jspecify.annotations.NonNull" />
         </list>
       </value>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">

.idea/runConfigurations.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="RunConfigurationProducerService">
+    <option name="ignoredProducers">
+      <set>
+        <option value="com.intellij.execution.junit.AbstractAllInDirectoryConfigurationProducer" />
+        <option value="com.intellij.execution.junit.AllInPackageConfigurationProducer" />
+        <option value="com.intellij.execution.junit.PatternConfigurationProducer" />
+        <option value="com.intellij.execution.junit.TestInClassConfigurationProducer" />
+        <option value="com.intellij.execution.junit.UniqueIdConfigurationProducer" />
+        <option value="com.intellij.execution.junit.testDiscovery.JUnitTestDiscoveryConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinJUnitRunConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinPatternConfigurationProducer" />
+      </set>
+    </option>
+  </component>
+</project>

README.md

@@ -1,6 +1,6 @@
 [![Actions Status](https://github.com/mik3y/usb-serial-for-android/workflows/build/badge.svg)](https://github.com/mik3y/usb-serial-for-android/actions)
 [![Jitpack](https://jitpack.io/v/mik3y/usb-serial-for-android.svg)](https://jitpack.io/#mik3y/usb-serial-for-android)
-[![Codacy](https://app.codacy.com/project/badge/Grade/ef799bba8a7343818af0a90eba3ecb46)](https://www.codacy.com/gh/kai-morich/usb-serial-for-android-mik3y/dashboard?utm_source=github.com&utm_medium=referral&utm_content=kai-morich/usb-serial-for-android-mik3y&utm_campaign=Badge_Grade)
+[![Codacy](https://app.codacy.com/project/badge/Grade/ef799bba8a7343818af0a90eba3ecb46)](https://app.codacy.com/gh/kai-morich/usb-serial-for-android-mik3y/dashboard?utm_source=gh&utm_medium=referral&utm_content=&utm_campaign=Badge_grade)
 [![codecov](https://codecov.io/gh/mik3y/usb-serial-for-android/branch/master/graph/badge.svg)](https://codecov.io/gh/mik3y/usb-serial-for-android)
 
 # usb-serial-for-android
@@ -37,10 +37,15 @@ dependencyResolutionManagement {
 }
 ```
 
+If using gradle kotlin  use line
+```gradle.kts
+        maven(url = "https://jitpack.io")
+```
+
 Add library to dependencies
 ```gradle
 dependencies {
-    implementation 'com.github.mik3y:usb-serial-for-android:3.5.1'
+    implementation 'com.github.mik3y:usb-serial-for-android:3.9.0'
 }
 ```
 
@@ -110,9 +115,10 @@ For a simple example, see
 [UsbSerialExamples](https://github.com/mik3y/usb-serial-for-android/blob/master/usbSerialExamples)
 folder in this project.
 
-For a more complete example with background service to stay connected while
-the app is not visible or rotating, see separate github project 
-[SimpleUsbTerminal](https://github.com/kai-morich/SimpleUsbTerminal).
+See separate github project [SimpleUsbTerminal](https://github.com/kai-morich/SimpleUsbTerminal) 
+for a more complete example with:
+* Background service to stay connected while the app is not visible or rotating
+* Flow control 
 
 ## Probing for Unrecognized Devices
 
@@ -139,8 +145,8 @@ UsbSerialProber prober = new UsbSerialProber(customTable);
 List<UsbSerialDriver> drivers = prober.findAllDrivers(usbManager);
 // ...
 ```
-*Note*: as of v3.5.0 this library detects CDC devices by USB interface types instead of fixed VID+PID,
-so custom probers are typically not required any more for CDC devices.
+*Note*: as of v3.5.0 this library detects CDC/ACM devices by USB interface types instead of fixed VID+PID,
+so custom probers are typically not required any more for CDC/ACM devices.
 
 Of course, nothing requires you to use UsbSerialProber at all: you can
 instantiate driver classes directly if you know what you're doing; just supply
@@ -148,16 +154,21 @@ a compatible UsbDevice.
 
 ## Compatible Devices
 
-This library supports USB to serial converter chips:
+This library supports USB to serial converter chips with specific drivers
 * FTDI FT232R, FT232H, FT2232H, FT4232H, FT230X, FT231X, FT234XD
 * Prolific PL2303
-* Silabs CP2102 and all other CP210x
-* Qinheng CH340, CH341A, CH9102
+* Silabs CP2102, CP210*
+* Qinheng CH340, CH341A
 
-and devices implementing the CDC/ACM protocol like
+some other device specific drivers
+* GsmModem devices, e.g. for Unisoc based Fibocom GSM modems
+* Chrome OS CCD (Closed Case Debugging)
+
+and devices implementing the generic CDC/ACM protocol like
+* Qinheng CH9102
+* Microchip MCP2221
 * Arduino using ATmega32U4
 * Digispark using V-USB software USB
-* BBC micro:bit using ARM mbed DAPLink firmware
 * ...
 
 ## Help & Discussion

build.gradle

@@ -6,7 +6,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.4.2'
+        classpath 'com.android.tools.build:gradle:8.9.1'
     }
 }
 

codecov.yml

@@ -0,0 +1,5 @@
+codecov:
+  max_report_age: off
+  require_ci_to_pass: no
+  notify:
+    wait_for_ci: no

gradle.properties

@@ -1,2 +1,3 @@
 android.enableJetifier=true
 android.useAndroidX=true
+android.defaults.buildfeatures.buildconfig=true

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-all.zip

jitpack.yml

@@ -1,4 +1,4 @@
 jdk:
-  - openjdk11
+  - openjdk17
 install:
   - ./gradlew :usbSerialForAndroid:publishToMavenLocal

test/pi_pico/README.md

@@ -0,0 +1,6 @@
+
+# `tinyusb_dev_cdc_dual_ports.uf2`
+
+compiled from `C:/Program Files/Raspberry Pi/Pico SDK v1.5.1/pico-sdk/lib/tinyusb/examples/device/cdc_dual_ports`
+to `C:/Users/` _user_`/Documents/Pico-v1.5.1/pico-examples/build/usb/device/tinyusb_device_examples/cdc_dual_ports/tinyusb_dev_cdc_dual_ports.uf2`
+

usbSerialExamples/build.gradle

@@ -3,7 +3,7 @@ plugins {
 }
 
 android {
-    compileSdkVersion 33
+    compileSdkVersion 35
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_8
@@ -12,7 +12,7 @@ android {
 
     defaultConfig {
         minSdkVersion 17
-        targetSdkVersion 33
+        targetSdkVersion 35
         vectorDrawables.useSupportLibrary = true
 
         missingDimensionStrategy 'device', 'anyDevice'
@@ -28,6 +28,6 @@ android {
 
 dependencies {
     implementation project(':usbSerialForAndroid')
-    implementation 'androidx.appcompat:appcompat:1.6.1'
-    implementation 'com.google.android.material:material:1.8.0'
+    implementation 'androidx.appcompat:appcompat:1.6.1' // later versions have minsdk 21
+    implementation 'com.google.android.material:material:1.11.0' // later versions have minsdk 19
 }

usbSerialExamples/src/main/java/com/hoho/android/usbserial/examples/TerminalFragment.java

@@ -28,6 +28,7 @@ import android.widget.ToggleButton;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.core.content.ContextCompat;
 import androidx.fragment.app.Fragment;
 
 import com.hoho.android.usbserial.driver.UsbSerialDriver;
@@ -89,12 +90,22 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
         withIoManager = getArguments().getBoolean("withIoManager");
     }
 
+    @Override
+    public void onStart() {
+        super.onStart();
+        ContextCompat.registerReceiver(getActivity(), broadcastReceiver, new IntentFilter(INTENT_ACTION_GRANT_USB), ContextCompat.RECEIVER_NOT_EXPORTED);
+    }
+
+    @Override
+    public void onStop() {
+        getActivity().unregisterReceiver(broadcastReceiver);
+        super.onStop();
+    }
+
     @Override
     public void onResume() {
         super.onResume();
-        getActivity().registerReceiver(broadcastReceiver, new IntentFilter(INTENT_ACTION_GRANT_USB));
-
-        if(usbPermission == UsbPermission.Unknown || usbPermission == UsbPermission.Granted)
+        if(!connected && (usbPermission == UsbPermission.Unknown || usbPermission == UsbPermission.Granted))
             mainLooper.post(this::connect);
     }
 
@@ -104,7 +115,6 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
             status("disconnected");
             disconnect();
         }
-        getActivity().unregisterReceiver(broadcastReceiver);
         super.onPause();
     }
 
@@ -204,7 +214,7 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
             status("connection failed: no driver for device");
             return;
         }
-        if(driver.getPorts().size() < portNum) {
+        if(portNum >= driver.getPorts().size()) {
             status("connection failed: not enough ports at device");
             return;
         }
@@ -213,7 +223,9 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
         if(usbConnection == null && usbPermission == UsbPermission.Unknown && !usbManager.hasPermission(driver.getDevice())) {
             usbPermission = UsbPermission.Requested;
             int flags = Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? PendingIntent.FLAG_MUTABLE : 0;
-            PendingIntent usbPermissionIntent = PendingIntent.getBroadcast(getActivity(), 0, new Intent(INTENT_ACTION_GRANT_USB), flags);
+            Intent intent = new Intent(INTENT_ACTION_GRANT_USB);
+            intent.setPackage(getActivity().getPackageName());
+            PendingIntent usbPermissionIntent = PendingIntent.getBroadcast(getActivity(), 0, intent, flags);
             usbManager.requestPermission(driver.getDevice(), usbPermissionIntent);
             return;
         }
@@ -227,7 +239,11 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
 
         try {
             usbSerialPort.open(usbConnection);
-            usbSerialPort.setParameters(baudRate, 8, 1, UsbSerialPort.PARITY_NONE);
+            try{
+                usbSerialPort.setParameters(baudRate, 8, 1, UsbSerialPort.PARITY_NONE);
+            }catch (UnsupportedOperationException e){
+                status("unsupport setparameters");
+            }
             if(withIoManager) {
                 usbIoManager = new SerialInputOutputManager(usbSerialPort, this);
                 usbIoManager.start();
@@ -351,7 +367,7 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
                 cdBtn.setChecked(controlLines.contains(UsbSerialPort.ControlLine.CD));
                 riBtn.setChecked(controlLines.contains(UsbSerialPort.ControlLine.RI));
                 mainLooper.postDelayed(runnable, refreshInterval);
-            } catch (IOException e) {
+            } catch (Exception e) {
                 status("getControlLines() failed: " + e.getMessage() + " -> stopped control line refresh");
             }
         }
@@ -368,8 +384,15 @@ public class TerminalFragment extends Fragment implements SerialInputOutputManag
                 if (!controlLines.contains(UsbSerialPort.ControlLine.CD))   cdBtn.setVisibility(View.INVISIBLE);
                 if (!controlLines.contains(UsbSerialPort.ControlLine.RI))   riBtn.setVisibility(View.INVISIBLE);
                 run();
-            } catch (IOException e) {
+            } catch (Exception e) {
                 Toast.makeText(getActivity(), "getSupportedControlLines() failed: " + e.getMessage(), Toast.LENGTH_SHORT).show();
+                rtsBtn.setVisibility(View.INVISIBLE);
+                ctsBtn.setVisibility(View.INVISIBLE);
+                dtrBtn.setVisibility(View.INVISIBLE);
+                dsrBtn.setVisibility(View.INVISIBLE);
+                cdBtn.setVisibility(View.INVISIBLE);
+                cdBtn.setVisibility(View.INVISIBLE);
+                riBtn.setVisibility(View.INVISIBLE);
             }
         }
 

usbSerialForAndroid/build.gradle

@@ -4,16 +4,16 @@ plugins {
 }
 
 android {
-    compileSdkVersion 33
+    compileSdkVersion 35
 
     defaultConfig {
         minSdkVersion 17
-        targetSdkVersion 33
+        targetSdkVersion 35
         consumerProguardFiles 'proguard-rules.pro'
         
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         testInstrumentationRunnerArguments = [                    // Raspi   Windows   LinuxVM   ...
-                'rfc2217_server_host': '192.168.0.144',
+                'rfc2217_server_host': '192.168.0.78',
                 'rfc2217_server_nonstandard_baudrates': 'true',   // true    false     false
         ]
     }
@@ -22,17 +22,23 @@ android {
         targetCompatibility JavaVersion.VERSION_1_8
     }
     namespace 'com.hoho.android.usbserial'
+    publishing {
+        // if coverage is enabled, change 'release' to 'anyDeviceRelease' or comment out publishing rule
+        singleVariant('release') {
+            withSourcesJar()
+        }
+    }
 }
 
 dependencies {
-    implementation "androidx.annotation:annotation:1.5.0"
-    //testImplementation 'androidx.test:core:1.5.0'
+    implementation "androidx.annotation:annotation:1.9.1"
     testImplementation 'junit:junit:4.13.2'
-    testImplementation 'org.mockito:mockito-core:1.10.19'
-    androidTestImplementation 'androidx.test:core:1.5.0'
-    androidTestImplementation 'androidx.test:runner:1.5.2'
-    androidTestImplementation 'commons-net:commons-net:3.8.0'
-    androidTestImplementation 'org.apache.commons:commons-lang3:3.11'
+    testImplementation 'org.mockito:mockito-core:5.15.2'
+    androidTestImplementation 'androidx.appcompat:appcompat:1.6.1' // later versions have minsdk 21
+    androidTestImplementation 'androidx.test:core:1.5.0' // later versions have minsdk 19
+    androidTestImplementation 'androidx.test:runner:1.5.2' // later versions have minsdk 19
+    androidTestImplementation 'commons-net:commons-net:3.9.0' // later versions fail on old Android devices with missing java.time.Duration class
+    androidTestImplementation 'org.apache.commons:commons-lang3:3.14.0'
 }
 
 // gradle task: publishToMavenLocal
@@ -40,21 +46,15 @@ project.afterEvaluate {
     publishing {
         publications {
             release(MavenPublication) {
-                from components.release // change 'release' to 'anyDeviceRelease' if coverage is enabled
-                artifact androidSourcesJar
+                from components.release
 
                 // values used for local maven repo, jitpack uses github release:
                 groupId 'com.github.mik3y'
                 artifactId 'usb-serial-for-android'
-                version '3.5.0beta'
+                version '3.8.0beta'
             }
         }
     }
 }
 
-task androidSourcesJar(type: Jar) {
-    classifier 'sources'
-    from android.sourceSets.main.java.srcDirs
-}
-
 //apply from: 'coverage.gradle'

usbSerialForAndroid/coverage.gradle

@@ -2,13 +2,13 @@
 apply plugin: 'jacoco'
 
 android {
-    flavorDimensions 'device'
+    flavorDimensions += 'device'
     productFlavors {
         anyDevice {
             // Used as fallback in usbSerialExample/build.gradle -> missingDimensionStrategy, but not for coverage report
             dimension 'device'
         }
-        arduino {
+        mcp2221 {
             dimension 'device'
             testInstrumentationRunnerArguments = ['test_device_driver': 'CdcAcm']
         }
@@ -18,7 +18,7 @@ android {
         }
         cp2102 { // and cp2105 first port
             dimension 'device'
-            testInstrumentationRunnerArguments = ['test_device_driver': 'Cp21xx']
+            testInstrumentationRunnerArguments = ['test_device_driver': 'Cp21xx', 'test_device_port': '0']
         }
         cp2105 { // second port
             dimension 'device'
@@ -26,7 +26,7 @@ android {
         }
         ft232 { // and ft2232 first port
             dimension 'device'
-            testInstrumentationRunnerArguments = ['test_device_driver': 'Ftdi']
+            testInstrumentationRunnerArguments = ['test_device_driver': 'Ftdi', 'test_device_port': '0']
         }
         ft2232 { // second port
             dimension 'device'

usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/util/UsbWrapper.java

@@ -18,6 +18,7 @@ import com.hoho.android.usbserial.driver.CommonUsbSerialPort;
 import com.hoho.android.usbserial.driver.Cp21xxSerialDriver;
 import com.hoho.android.usbserial.driver.FtdiSerialDriver;
 import com.hoho.android.usbserial.driver.ProlificSerialDriver;
+import com.hoho.android.usbserial.driver.ProlificSerialPortWrapper;
 import com.hoho.android.usbserial.driver.UsbId;
 import com.hoho.android.usbserial.driver.UsbSerialDriver;
 import com.hoho.android.usbserial.driver.UsbSerialPort;
@@ -32,6 +33,8 @@ import java.util.concurrent.Callable;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
+import androidx.core.content.ContextCompat;
+
 public class UsbWrapper implements SerialInputOutputManager.Listener {
 
     public final static int     USB_READ_WAIT = 500;
@@ -56,11 +59,13 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
 
     // device properties
     public boolean isCp21xxRestrictedPort; // second port of Cp2105 has limited dataBits, stopBits, parity
+    public boolean outputLinesSupported;
     public boolean inputLinesSupported;
     public boolean inputLinesConnected;
     public boolean inputLinesOnlyRtsCts;
     public int writePacketSize = -1;
     public int writeBufferSize = -1;
+    public int readBufferSize = -1;
 
     public UsbWrapper(Context context, UsbSerialDriver serialDriver, int devicePort) {
         this.context = context;
@@ -85,9 +90,11 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
                 }
             };
             int flags = Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? PendingIntent.FLAG_MUTABLE : 0;
-            PendingIntent permissionIntent = PendingIntent.getBroadcast(context, 0, new Intent("com.android.example.USB_PERMISSION"), flags);
+            Intent intent = new Intent("com.android.example.USB_PERMISSION");
+            intent.setPackage(context.getPackageName());
+            PendingIntent permissionIntent = PendingIntent.getBroadcast(context, 0, intent, flags);
             IntentFilter filter = new IntentFilter("com.android.example.USB_PERMISSION");
-            context.registerReceiver(usbReceiver, filter);
+            ContextCompat.registerReceiver(context, usbReceiver, filter, Context.RECEIVER_NOT_EXPORTED);
             usbManager.requestPermission(serialDriver.getDevice(), permissionIntent);
             for(int i=0; i<5000; i++) {
                 if(granted[0] != null) break;
@@ -99,9 +106,10 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
 
         // extract some device properties:
         isCp21xxRestrictedPort = serialDriver instanceof Cp21xxSerialDriver && serialDriver.getPorts().size()==2 && serialPort.getPortNumber() == 1;
-        // output lines are supported by all drivers
-        // input lines are supported by all drivers except CDC
+        // output lines are supported by all common drivers
+        // input lines are supported by all common drivers except CDC
         if (serialDriver instanceof FtdiSerialDriver) {
+            outputLinesSupported = true;
             inputLinesSupported = true;
             if(serialDriver.getDevice().getProductId() == UsbId.FTDI_FT2232H)
                 inputLinesConnected = true; // I only have 74LS138 connected at FT2232, not at FT232
@@ -110,16 +118,21 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
                 inputLinesOnlyRtsCts = true; // I only test with FT230X that has only these 2 control lines. DTR is silently ignored
             }
         } else if (serialDriver instanceof Cp21xxSerialDriver) {
+            outputLinesSupported = true;
             inputLinesSupported = true;
             if(serialDriver.getPorts().size() == 1)
                 inputLinesConnected = true; // I only have 74LS138 connected at CP2102, not at CP2105
         } else if (serialDriver instanceof ProlificSerialDriver) {
+            outputLinesSupported = true;
             inputLinesSupported = true;
             inputLinesConnected = true;
         } else if (serialDriver instanceof Ch34xSerialDriver) {
+            outputLinesSupported = true;
             inputLinesSupported = true;
             if(serialDriver.getDevice().getProductId() == UsbId.QINHENG_CH340)
                 inputLinesConnected = true;  // I only have 74LS138 connected at CH340, not connected at CH341A
+        } else if (serialDriver instanceof CdcAcmSerialDriver) {
+            outputLinesSupported = true;
         }
 
         if (serialDriver instanceof Cp21xxSerialDriver) {
@@ -136,10 +149,18 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
                 case 2: writePacketSize = 512; writeBufferSize = 4096; break;
                 case 4: writePacketSize = 512; writeBufferSize = 2048; break;
             }
+            if(serialDriver.getDevice().getProductId() == UsbId.FTDI_FT231X)
+                writeBufferSize = 512;
         } else if (serialDriver instanceof CdcAcmSerialDriver) {
-            writePacketSize = 64; writeBufferSize = 128;
+            writePacketSize = 16; writeBufferSize = 32; // MCP2221 values, other devices might be different
         }
 
+        readBufferSize = writeBufferSize;
+        if (serialDriver instanceof Cp21xxSerialDriver && serialDriver.getPorts().size() == 2) {
+            readBufferSize = 256;
+        } else if (serialDriver instanceof FtdiSerialDriver && serialDriver.getPorts().size() == 1 && serialDriver.getDevice().getProductId() != UsbId.FTDI_FT231X) {
+            readBufferSize = 256;
+        } // PL2303 HXN checked in open()
     }
 
     public void tearDown() {
@@ -168,6 +189,8 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
                 if(!flags.contains(OpenCloseFlags.NO_CONTROL_LINE_INIT)) {
                     serialPort.setDTR(false);
                     serialPort.setRTS(false);
+                    if (serialPort.getFlowControl() != UsbSerialPort.FlowControl.NONE)
+                        serialPort.setFlowControl(UsbSerialPort.FlowControl.NONE);
                 }
             } catch (Exception ignored) {
             }
@@ -217,6 +240,10 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
             readBuffer.clear();
         }
         readError = null;
+
+        if (serialDriver instanceof ProlificSerialDriver && ProlificSerialPortWrapper.isDeviceTypeHxn(serialPort)) {
+            readBufferSize = 768;
+        }
     }
 
     public void waitForIoManagerStarted() throws IOException {
@@ -231,12 +258,15 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
         throw new IOException("IoManager not started");
     }
 
-    public boolean hasIoManagerThread() {
+    public boolean hasIoManagerThreads() {
+        int c = 0;
         for (Thread thread : Thread.getAllStackTraces().keySet()) {
-            if (thread.getName().equals(SerialInputOutputManager.class.getSimpleName()))
-                return true;
+            if (thread.getName().equals(SerialInputOutputManager.class.getSimpleName() + "_read"))
+                c += 1;
+            if (thread.getName().equals(SerialInputOutputManager.class.getSimpleName() + "_write"))
+                c += 1;
         }
-        return false;
+        return c == 2;
     }
 
     // wait full time

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java

@@ -12,6 +12,9 @@ import android.hardware.usb.UsbEndpoint;
 import android.hardware.usb.UsbInterface;
 import android.util.Log;
 
+import com.hoho.android.usbserial.util.HexDump;
+import com.hoho.android.usbserial.util.UsbUtils;
+
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.EnumSet;
@@ -29,6 +32,8 @@ import java.util.Map;
  */
 public class CdcAcmSerialDriver implements UsbSerialDriver {
 
+    public static final int USB_SUBCLASS_ACM = 2;
+
     private final String TAG = CdcAcmSerialDriver.class.getSimpleName();
 
     private final UsbDevice mDevice;
@@ -55,7 +60,8 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
         int controlInterfaceCount = 0;
         int dataInterfaceCount = 0;
         for (int i = 0; i < device.getInterfaceCount(); i++) {
-            if (device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_COMM)
+            if (device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_COMM &&
+                    device.getInterface(i).getInterfaceSubclass() == USB_SUBCLASS_ACM)
                 controlInterfaceCount++;
             if (device.getInterface(i).getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA)
                 dataInterfaceCount++;
@@ -104,6 +110,10 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
 
         @Override
         protected void openInt() throws IOException {
+            Log.d(TAG, "interfaces:");
+            for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
+                Log.d(TAG, mDevice.getInterface(i).toString());
+            }
             if (mPortNumber == -1) {
                 Log.d(TAG,"device might be castrated ACM device, trying single interface logic");
                 openSingleInterface();
@@ -139,50 +149,57 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
         }
 
         private void openInterface() throws IOException {
-            Log.d(TAG, "claiming interfaces, count=" + mDevice.getInterfaceCount());
 
-            int rndisControlInterfaceCount = 0;
-            int controlInterfaceCount = 0;
-            int dataInterfaceCount = 0;
             mControlInterface = null;
             mDataInterface = null;
-            for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
-                UsbInterface usbInterface = mDevice.getInterface(i);
-                if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_COMM) {
-                    if(controlInterfaceCount == mPortNumber) {
-                        mControlIndex = usbInterface.getId();
-                        mControlInterface = usbInterface;
+            int j = getInterfaceIdFromDescriptors();
+            Log.d(TAG, "interface count=" + mDevice.getInterfaceCount() + ", IAD=" + j);
+            if (j >= 0) {
+                for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
+                    UsbInterface usbInterface = mDevice.getInterface(i);
+                    if (usbInterface.getId() == j || usbInterface.getId() == j+1) {
+                        if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_COMM &&
+                                usbInterface.getInterfaceSubclass() == USB_SUBCLASS_ACM) {
+                            mControlIndex = usbInterface.getId();
+                            mControlInterface = usbInterface;
+                        }
+                        if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA) {
+                            mDataInterface = usbInterface;
+                        }
                     }
-                    controlInterfaceCount++;
                 }
-                if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA) {
-                    if(dataInterfaceCount == mPortNumber + rndisControlInterfaceCount) {
-                        mDataInterface = usbInterface;
+            }
+            if (mControlInterface == null || mDataInterface == null) {
+                Log.d(TAG, "no IAD fallback");
+                int controlInterfaceCount = 0;
+                int dataInterfaceCount = 0;
+                for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
+                    UsbInterface usbInterface = mDevice.getInterface(i);
+                    if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_COMM &&
+                            usbInterface.getInterfaceSubclass() == USB_SUBCLASS_ACM) {
+                        if (controlInterfaceCount == mPortNumber) {
+                            mControlIndex = usbInterface.getId();
+                            mControlInterface = usbInterface;
+                        }
+                        controlInterfaceCount++;
+                    }
+                    if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_CDC_DATA) {
+                        if (dataInterfaceCount == mPortNumber) {
+                            mDataInterface = usbInterface;
+                        }
+                        dataInterfaceCount++;
                     }
-                    dataInterfaceCount++;
-                }
-                if (mDataInterface == null &&
-                        usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_WIRELESS_CONTROLLER &&
-                        usbInterface.getInterfaceSubclass() == 1 &&
-                        usbInterface.getInterfaceProtocol() == 3) {
-                    /*
-                     * RNDIS is a MSFT variant of CDC-ACM states the Linux kernel in rndis_host.c
-                     * The devices provide IAD descriptors to indicate consecutive interfaces belonging
-                     * together, but this is not exposed to Java. So simply skip related data interfaces.
-                     */
-                    rndisControlInterfaceCount++;
                 }
             }
 
             if(mControlInterface == null) {
                 throw new IOException("No control interface");
             }
-            Log.d(TAG, "Control iface=" + mControlInterface);
+            Log.d(TAG, "Control interface id " + mControlInterface.getId());
 
             if (!mConnection.claimInterface(mControlInterface, true)) {
                 throw new IOException("Could not claim control interface");
             }
-
             mControlEndpoint = mControlInterface.getEndpoint(0);
             if (mControlEndpoint.getDirection() != UsbConstants.USB_DIR_IN || mControlEndpoint.getType() != UsbConstants.USB_ENDPOINT_XFER_INT) {
                 throw new IOException("Invalid control endpoint");
@@ -191,12 +208,10 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
             if(mDataInterface == null) {
                 throw new IOException("No data interface");
             }
-            Log.d(TAG, "data iface=" + mDataInterface);
-
+            Log.d(TAG, "data interface id " + mDataInterface.getId());
             if (!mConnection.claimInterface(mDataInterface, true)) {
                 throw new IOException("Could not claim data interface");
             }
-
             for (int i = 0; i < mDataInterface.getEndpointCount(); i++) {
                 UsbEndpoint ep = mDataInterface.getEndpoint(i);
                 if (ep.getDirection() == UsbConstants.USB_DIR_IN && ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)
@@ -206,6 +221,36 @@ public class CdcAcmSerialDriver implements UsbSerialDriver {
             }
         }
 
+        private int getInterfaceIdFromDescriptors() {
+            ArrayList<byte[]> descriptors = UsbUtils.getDescriptors(mConnection);
+            Log.d(TAG, "USB descriptor:");
+            for(byte[] descriptor : descriptors)
+                Log.d(TAG, HexDump.toHexString(descriptor));
+
+            if (descriptors.size() > 0 &&
+                    descriptors.get(0).length == 18 &&
+                    descriptors.get(0)[1] == 1 && // bDescriptorType
+                    descriptors.get(0)[4] == (byte)(UsbConstants.USB_CLASS_MISC) && //bDeviceClass
+                    descriptors.get(0)[5] == 2 && // bDeviceSubClass
+                    descriptors.get(0)[6] == 1) { // bDeviceProtocol
+                // is IAD device, see https://www.usb.org/sites/default/files/iadclasscode_r10.pdf
+                int port = -1;
+                for (int d = 1; d < descriptors.size(); d++) {
+                    if (descriptors.get(d).length == 8 &&
+                            descriptors.get(d)[1] == 0x0b && // bDescriptorType == IAD
+                            descriptors.get(d)[4] == UsbConstants.USB_CLASS_COMM && // bFunctionClass == CDC
+                            descriptors.get(d)[5] == USB_SUBCLASS_ACM) { // bFunctionSubClass == ACM
+                        port++;
+                        if (port == mPortNumber &&
+                                descriptors.get(d)[3] == 2) { // bInterfaceCount
+                            return descriptors.get(d)[2]; // bFirstInterface
+                        }
+                    }
+                }
+            }
+            return -1;
+        }
+
         private int sendAcmControlMessage(int request, int value, byte[] buf) throws IOException {
             int len = mConnection.controlTransfer(
                     USB_RT_ACM, request, value, mControlIndex, buf, buf != null ? buf.length : 0, 5000);

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/Ch34xSerialDriver.java

@@ -22,366 +22,366 @@ import java.util.Map;
 
 public class Ch34xSerialDriver implements UsbSerialDriver {
 
-	private static final String TAG = Ch34xSerialDriver.class.getSimpleName();
+    private static final String TAG = Ch34xSerialDriver.class.getSimpleName();
 
-	private final UsbDevice mDevice;
-	private final UsbSerialPort mPort;
+    private final UsbDevice mDevice;
+    private final UsbSerialPort mPort;
 
-	private static final int LCR_ENABLE_RX   = 0x80;
-	private static final int LCR_ENABLE_TX   = 0x40;
-	private static final int LCR_MARK_SPACE  = 0x20;
-	private static final int LCR_PAR_EVEN    = 0x10;
-	private static final int LCR_ENABLE_PAR  = 0x08;
-	private static final int LCR_STOP_BITS_2 = 0x04;
-	private static final int LCR_CS8         = 0x03;
-	private static final int LCR_CS7         = 0x02;
-	private static final int LCR_CS6         = 0x01;
-	private static final int LCR_CS5         = 0x00;
+    private static final int LCR_ENABLE_RX   = 0x80;
+    private static final int LCR_ENABLE_TX   = 0x40;
+    private static final int LCR_MARK_SPACE  = 0x20;
+    private static final int LCR_PAR_EVEN    = 0x10;
+    private static final int LCR_ENABLE_PAR  = 0x08;
+    private static final int LCR_STOP_BITS_2 = 0x04;
+    private static final int LCR_CS8         = 0x03;
+    private static final int LCR_CS7         = 0x02;
+    private static final int LCR_CS6         = 0x01;
+    private static final int LCR_CS5         = 0x00;
 
-	private static final int GCL_CTS = 0x01;
-	private static final int GCL_DSR = 0x02;
-	private static final int GCL_RI  = 0x04;
-	private static final int GCL_CD  = 0x08;
-	private static final int SCL_DTR = 0x20;
-	private static final int SCL_RTS = 0x40;
+    private static final int GCL_CTS = 0x01;
+    private static final int GCL_DSR = 0x02;
+    private static final int GCL_RI  = 0x04;
+    private static final int GCL_CD  = 0x08;
+    private static final int SCL_DTR = 0x20;
+    private static final int SCL_RTS = 0x40;
 
-	public Ch34xSerialDriver(UsbDevice device) {
-		mDevice = device;
-		mPort = new Ch340SerialPort(mDevice, 0);
-	}
+    public Ch34xSerialDriver(UsbDevice device) {
+        mDevice = device;
+        mPort = new Ch340SerialPort(mDevice, 0);
+    }
 
-	@Override
-	public UsbDevice getDevice() {
-		return mDevice;
-	}
+    @Override
+    public UsbDevice getDevice() {
+        return mDevice;
+    }
 
-	@Override
-	public List<UsbSerialPort> getPorts() {
-		return Collections.singletonList(mPort);
-	}
+    @Override
+    public List<UsbSerialPort> getPorts() {
+        return Collections.singletonList(mPort);
+    }
 
-	public class Ch340SerialPort extends CommonUsbSerialPort {
+    public class Ch340SerialPort extends CommonUsbSerialPort {
 
-		private static final int USB_TIMEOUT_MILLIS = 5000;
+        private static final int USB_TIMEOUT_MILLIS = 5000;
 
-		private final int DEFAULT_BAUD_RATE = 9600;
+        private final int DEFAULT_BAUD_RATE = 9600;
 
-		private boolean dtr = false;
-		private boolean rts = false;
+        private boolean dtr = false;
+        private boolean rts = false;
 
-		public Ch340SerialPort(UsbDevice device, int portNumber) {
-			super(device, portNumber);
-		}
+        public Ch340SerialPort(UsbDevice device, int portNumber) {
+            super(device, portNumber);
+        }
 
-		@Override
-		public UsbSerialDriver getDriver() {
-			return Ch34xSerialDriver.this;
-		}
+        @Override
+        public UsbSerialDriver getDriver() {
+            return Ch34xSerialDriver.this;
+        }
 
-		@Override
-		protected void openInt() throws IOException {
-			for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
-				UsbInterface usbIface = mDevice.getInterface(i);
-				if (!mConnection.claimInterface(usbIface, true)) {
-					throw new IOException("Could not claim data interface");
-				}
-			}
+        @Override
+        protected void openInt() throws IOException {
+            for (int i = 0; i < mDevice.getInterfaceCount(); i++) {
+                UsbInterface usbIface = mDevice.getInterface(i);
+                if (!mConnection.claimInterface(usbIface, true)) {
+                    throw new IOException("Could not claim data interface");
+                }
+            }
 
-			UsbInterface dataIface = mDevice.getInterface(mDevice.getInterfaceCount() - 1);
-			for (int i = 0; i < dataIface.getEndpointCount(); i++) {
-				UsbEndpoint ep = dataIface.getEndpoint(i);
-				if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {
-					if (ep.getDirection() == UsbConstants.USB_DIR_IN) {
-						mReadEndpoint = ep;
-					} else {
-						mWriteEndpoint = ep;
-					}
-				}
-			}
+            UsbInterface dataIface = mDevice.getInterface(mDevice.getInterfaceCount() - 1);
+            for (int i = 0; i < dataIface.getEndpointCount(); i++) {
+                UsbEndpoint ep = dataIface.getEndpoint(i);
+                if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {
+                    if (ep.getDirection() == UsbConstants.USB_DIR_IN) {
+                        mReadEndpoint = ep;
+                    } else {
+                        mWriteEndpoint = ep;
+                    }
+                }
+            }
 
-			initialize();
-			setBaudRate(DEFAULT_BAUD_RATE);
-		}
+            initialize();
+            setBaudRate(DEFAULT_BAUD_RATE);
+        }
 
-		@Override
-		protected void closeInt() {
-			try {
-				for (int i = 0; i < mDevice.getInterfaceCount(); i++)
-					mConnection.releaseInterface(mDevice.getInterface(i));
-			} catch(Exception ignored) {}
-		}
+        @Override
+        protected void closeInt() {
+            try {
+                for (int i = 0; i < mDevice.getInterfaceCount(); i++)
+                    mConnection.releaseInterface(mDevice.getInterface(i));
+            } catch(Exception ignored) {}
+        }
 
-		private int controlOut(int request, int value, int index) {
-			final int REQTYPE_HOST_TO_DEVICE = UsbConstants.USB_TYPE_VENDOR | UsbConstants.USB_DIR_OUT;
-			return mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, request,
-					value, index, null, 0, USB_TIMEOUT_MILLIS);
-		}
+        private int controlOut(int request, int value, int index) {
+            final int REQTYPE_HOST_TO_DEVICE = UsbConstants.USB_TYPE_VENDOR | UsbConstants.USB_DIR_OUT;
+            return mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, request,
+                    value, index, null, 0, USB_TIMEOUT_MILLIS);
+        }
 
 
-		private int controlIn(int request, int value, int index, byte[] buffer) {
-			final int REQTYPE_DEVICE_TO_HOST = UsbConstants.USB_TYPE_VENDOR | UsbConstants.USB_DIR_IN;
-			return mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, request,
-					value, index, buffer, buffer.length, USB_TIMEOUT_MILLIS);
-		}
+        private int controlIn(int request, int value, int index, byte[] buffer) {
+            final int REQTYPE_DEVICE_TO_HOST = UsbConstants.USB_TYPE_VENDOR | UsbConstants.USB_DIR_IN;
+            return mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, request,
+                    value, index, buffer, buffer.length, USB_TIMEOUT_MILLIS);
+        }
 
 
-		private void checkState(String msg, int request, int value, int[] expected) throws IOException {
-			byte[] buffer = new byte[expected.length];
-			int ret = controlIn(request, value, 0, buffer);
+        private void checkState(String msg, int request, int value, int[] expected) throws IOException {
+            byte[] buffer = new byte[expected.length];
+            int ret = controlIn(request, value, 0, buffer);
 
-			if (ret < 0) {
-				throw new IOException("Failed send cmd [" + msg + "]");
-			}
+            if (ret < 0) {
+                throw new IOException("Failed send cmd [" + msg + "]");
+            }
 
-			if (ret != expected.length) {
-				throw new IOException("Expected " + expected.length + " bytes, but get " + ret + " [" + msg + "]");
-			}
+            if (ret != expected.length) {
+                throw new IOException("Expected " + expected.length + " bytes, but get " + ret + " [" + msg + "]");
+            }
 
-			for (int i = 0; i < expected.length; i++) {
-				if (expected[i] == -1) {
-					continue;
-				}
+            for (int i = 0; i < expected.length; i++) {
+                if (expected[i] == -1) {
+                    continue;
+                }
 
-				int current = buffer[i] & 0xff;
-				if (expected[i] != current) {
-					throw new IOException("Expected 0x" + Integer.toHexString(expected[i]) + " byte, but get 0x" + Integer.toHexString(current) + " [" + msg + "]");
-				}
-			}
-		}
+                int current = buffer[i] & 0xff;
+                if (expected[i] != current) {
+                    throw new IOException("Expected 0x" + Integer.toHexString(expected[i]) + " byte, but get 0x" + Integer.toHexString(current) + " [" + msg + "]");
+                }
+            }
+        }
 
-		private void setControlLines() throws IOException {
-			if (controlOut(0xa4, ~((dtr ? SCL_DTR : 0) | (rts ? SCL_RTS : 0)), 0) < 0) {
-				throw new IOException("Failed to set control lines");
-			}
-		}
+        private void setControlLines() throws IOException {
+            if (controlOut(0xa4, ~((dtr ? SCL_DTR : 0) | (rts ? SCL_RTS : 0)), 0) < 0) {
+                throw new IOException("Failed to set control lines");
+            }
+        }
 
-		private byte getStatus() throws IOException {
-			byte[] buffer = new byte[2];
-			int ret = controlIn(0x95, 0x0706, 0, buffer);
-			if (ret < 0)
-				throw new IOException("Error getting control lines");
-			return buffer[0];
-		}
+        private byte getStatus() throws IOException {
+            byte[] buffer = new byte[2];
+            int ret = controlIn(0x95, 0x0706, 0, buffer);
+            if (ret < 0)
+                throw new IOException("Error getting control lines");
+            return buffer[0];
+        }
 
-		private void initialize() throws IOException {
-			checkState("init #1", 0x5f, 0, new int[]{-1 /* 0x27, 0x30 */, 0x00});
+        private void initialize() throws IOException {
+            checkState("init #1", 0x5f, 0, new int[]{-1 /* 0x27, 0x30 */, 0x00});
 
-			if (controlOut(0xa1, 0, 0) < 0) {
-				throw new IOException("Init failed: #2");
-			}
+            if (controlOut(0xa1, 0, 0) < 0) {
+                throw new IOException("Init failed: #2");
+            }
 
-			setBaudRate(DEFAULT_BAUD_RATE);
+            setBaudRate(DEFAULT_BAUD_RATE);
 
-			checkState("init #4", 0x95, 0x2518, new int[]{-1 /* 0x56, c3*/, 0x00});
+            checkState("init #4", 0x95, 0x2518, new int[]{-1 /* 0x56, c3*/, 0x00});
 
-			if (controlOut(0x9a, 0x2518, LCR_ENABLE_RX | LCR_ENABLE_TX | LCR_CS8) < 0) {
-				throw new IOException("Init failed: #5");
-			}
+            if (controlOut(0x9a, 0x2518, LCR_ENABLE_RX | LCR_ENABLE_TX | LCR_CS8) < 0) {
+                throw new IOException("Init failed: #5");
+            }
 
-			checkState("init #6", 0x95, 0x0706, new int[]{-1/*0xf?*/, -1/*0xec,0xee*/});
+            checkState("init #6", 0x95, 0x0706, new int[]{-1/*0xf?*/, -1/*0xec,0xee*/});
 
-			if (controlOut(0xa1, 0x501f, 0xd90a) < 0) {
-				throw new IOException("Init failed: #7");
-			}
+            if (controlOut(0xa1, 0x501f, 0xd90a) < 0) {
+                throw new IOException("Init failed: #7");
+            }
 
-			setBaudRate(DEFAULT_BAUD_RATE);
+            setBaudRate(DEFAULT_BAUD_RATE);
 
-			setControlLines();
+            setControlLines();
 
-			checkState("init #10", 0x95, 0x0706, new int[]{-1/* 0x9f, 0xff*/, -1/*0xec,0xee*/});
-		}
+            checkState("init #10", 0x95, 0x0706, new int[]{-1/* 0x9f, 0xff*/, -1/*0xec,0xee*/});
+        }
 
 
-		private void setBaudRate(int baudRate) throws IOException {
-			long factor;
-			long divisor;
+        private void setBaudRate(int baudRate) throws IOException {
+            long factor;
+            long divisor;
 
-			if (baudRate == 921600) {
-				divisor = 7;
-				factor = 0xf300;
-			} else {
-				final long BAUDBASE_FACTOR = 1532620800;
-				final int BAUDBASE_DIVMAX = 3;
+            if (baudRate == 921600) {
+                divisor = 7;
+                factor = 0xf300;
+            } else {
+                final long BAUDBASE_FACTOR = 1532620800;
+                final int BAUDBASE_DIVMAX = 3;
 
-				if(BuildConfig.DEBUG && (baudRate & (3<<29)) == (1<<29))
-					baudRate &= ~(1<<29); // for testing purpose bypass dedicated baud rate handling
-				factor = BAUDBASE_FACTOR / baudRate;
-				divisor = BAUDBASE_DIVMAX;
-				while ((factor > 0xfff0) && divisor > 0) {
-					factor >>= 3;
-					divisor--;
-				}
-				if (factor > 0xfff0) {
-					throw new UnsupportedOperationException("Unsupported baud rate: " + baudRate);
-				}
-				factor = 0x10000 - factor;
-			}
+                if(BuildConfig.DEBUG && (baudRate & (3<<29)) == (1<<29))
+                    baudRate &= ~(1<<29); // for testing purpose bypass dedicated baud rate handling
+                factor = BAUDBASE_FACTOR / baudRate;
+                divisor = BAUDBASE_DIVMAX;
+                while ((factor > 0xfff0) && divisor > 0) {
+                    factor >>= 3;
+                    divisor--;
+                }
+                if (factor > 0xfff0) {
+                    throw new UnsupportedOperationException("Unsupported baud rate: " + baudRate);
+                }
+                factor = 0x10000 - factor;
+            }
 
-			divisor |= 0x0080; // else ch341a waits until buffer full
-			int val1 = (int) ((factor & 0xff00) | divisor);
-			int val2 = (int) (factor & 0xff);
-			Log.d(TAG, String.format("baud rate=%d, 0x1312=0x%04x, 0x0f2c=0x%04x", baudRate, val1, val2));
-			int ret = controlOut(0x9a, 0x1312, val1);
-			if (ret < 0) {
-				throw new IOException("Error setting baud rate: #1)");
-			}
-			ret = controlOut(0x9a, 0x0f2c, val2);
-			if (ret < 0) {
-				throw new IOException("Error setting baud rate: #2");
-			}
-		}
+            divisor |= 0x0080; // else ch341a waits until buffer full
+            int val1 = (int) ((factor & 0xff00) | divisor);
+            int val2 = (int) (factor & 0xff);
+            Log.d(TAG, String.format("baud rate=%d, 0x1312=0x%04x, 0x0f2c=0x%04x", baudRate, val1, val2));
+            int ret = controlOut(0x9a, 0x1312, val1);
+            if (ret < 0) {
+                throw new IOException("Error setting baud rate: #1)");
+            }
+            ret = controlOut(0x9a, 0x0f2c, val2);
+            if (ret < 0) {
+                throw new IOException("Error setting baud rate: #2");
+            }
+        }
 
-		@Override
-		public void setParameters(int baudRate, int dataBits, int stopBits, @Parity int parity) throws IOException {
-			if(baudRate <= 0) {
-				throw new IllegalArgumentException("Invalid baud rate: " + baudRate);
-			}
-			setBaudRate(baudRate);
+        @Override
+        public void setParameters(int baudRate, int dataBits, int stopBits, @Parity int parity) throws IOException {
+            if(baudRate <= 0) {
+                throw new IllegalArgumentException("Invalid baud rate: " + baudRate);
+            }
+            setBaudRate(baudRate);
 
-			int lcr = LCR_ENABLE_RX | LCR_ENABLE_TX;
+            int lcr = LCR_ENABLE_RX | LCR_ENABLE_TX;
 
-			switch (dataBits) {
-				case DATABITS_5:
-					lcr |= LCR_CS5;
-					break;
-				case DATABITS_6:
-					lcr |= LCR_CS6;
-					break;
-				case DATABITS_7:
-					lcr |= LCR_CS7;
-					break;
-				case DATABITS_8:
-					lcr |= LCR_CS8;
-					break;
-				default:
-					throw new IllegalArgumentException("Invalid data bits: " + dataBits);
-			}
+            switch (dataBits) {
+                case DATABITS_5:
+                    lcr |= LCR_CS5;
+                    break;
+                case DATABITS_6:
+                    lcr |= LCR_CS6;
+                    break;
+                case DATABITS_7:
+                    lcr |= LCR_CS7;
+                    break;
+                case DATABITS_8:
+                    lcr |= LCR_CS8;
+                    break;
+                default:
+                    throw new IllegalArgumentException("Invalid data bits: " + dataBits);
+            }
 
-			switch (parity) {
-				case PARITY_NONE:
-					break;
-				case PARITY_ODD:
-					lcr |= LCR_ENABLE_PAR;
-					break;
-				case PARITY_EVEN:
-					lcr |= LCR_ENABLE_PAR | LCR_PAR_EVEN;
-					break;
-				case PARITY_MARK:
-					lcr |= LCR_ENABLE_PAR | LCR_MARK_SPACE;
-					break;
-				case PARITY_SPACE:
-					lcr |= LCR_ENABLE_PAR | LCR_MARK_SPACE | LCR_PAR_EVEN;
-					break;
-				default:
-					throw new IllegalArgumentException("Invalid parity: " + parity);
-			}
+            switch (parity) {
+                case PARITY_NONE:
+                    break;
+                case PARITY_ODD:
+                    lcr |= LCR_ENABLE_PAR;
+                    break;
+                case PARITY_EVEN:
+                    lcr |= LCR_ENABLE_PAR | LCR_PAR_EVEN;
+                    break;
+                case PARITY_MARK:
+                    lcr |= LCR_ENABLE_PAR | LCR_MARK_SPACE;
+                    break;
+                case PARITY_SPACE:
+                    lcr |= LCR_ENABLE_PAR | LCR_MARK_SPACE | LCR_PAR_EVEN;
+                    break;
+                default:
+                    throw new IllegalArgumentException("Invalid parity: " + parity);
+            }
 
-			switch (stopBits) {
-				case STOPBITS_1:
-					break;
-				case STOPBITS_1_5:
-					throw new UnsupportedOperationException("Unsupported stop bits: 1.5");
-				case STOPBITS_2:
-					lcr |= LCR_STOP_BITS_2;
-					break;
-				default:
-					throw new IllegalArgumentException("Invalid stop bits: " + stopBits);
-			}
+            switch (stopBits) {
+                case STOPBITS_1:
+                    break;
+                case STOPBITS_1_5:
+                    throw new UnsupportedOperationException("Unsupported stop bits: 1.5");
+                case STOPBITS_2:
+                    lcr |= LCR_STOP_BITS_2;
+                    break;
+                default:
+                    throw new IllegalArgumentException("Invalid stop bits: " + stopBits);
+            }
 
-			int ret = controlOut(0x9a, 0x2518, lcr);
-			if (ret < 0) {
-				throw new IOException("Error setting control byte");
-			}
-		}
+            int ret = controlOut(0x9a, 0x2518, lcr);
+            if (ret < 0) {
+                throw new IOException("Error setting control byte");
+            }
+        }
 
-		@Override
-		public boolean getCD() throws IOException {
-			return (getStatus() & GCL_CD) == 0;
-		}
+        @Override
+        public boolean getCD() throws IOException {
+            return (getStatus() & GCL_CD) == 0;
+        }
 
-		@Override
-		public boolean getCTS() throws IOException {
-			return (getStatus() & GCL_CTS) == 0;
-		}
+        @Override
+        public boolean getCTS() throws IOException {
+            return (getStatus() & GCL_CTS) == 0;
+        }
 
-		@Override
-		public boolean getDSR() throws IOException {
-			return (getStatus() & GCL_DSR) == 0;
-		}
+        @Override
+        public boolean getDSR() throws IOException {
+            return (getStatus() & GCL_DSR) == 0;
+        }
 
-		@Override
-		public boolean getDTR() throws IOException {
-			return dtr;
-		}
+        @Override
+        public boolean getDTR() throws IOException {
+            return dtr;
+        }
 
-		@Override
-		public void setDTR(boolean value) throws IOException {
-			dtr = value;
-			setControlLines();
-		}
+        @Override
+        public void setDTR(boolean value) throws IOException {
+            dtr = value;
+            setControlLines();
+        }
 
-		@Override
-		public boolean getRI() throws IOException {
-			return (getStatus() & GCL_RI) == 0;
-		}
+        @Override
+        public boolean getRI() throws IOException {
+            return (getStatus() & GCL_RI) == 0;
+        }
 
-		@Override
-		public boolean getRTS() throws IOException {
-			return rts;
-		}
+        @Override
+        public boolean getRTS() throws IOException {
+            return rts;
+        }
 
-		@Override
-		public void setRTS(boolean value) throws IOException {
-			rts = value;
-			setControlLines();
-		}
+        @Override
+        public void setRTS(boolean value) throws IOException {
+            rts = value;
+            setControlLines();
+        }
 
-		@Override
-		public EnumSet<ControlLine> getControlLines() throws IOException {
-			int status = getStatus();
-			EnumSet<ControlLine> set = EnumSet.noneOf(ControlLine.class);
-			if(rts) set.add(ControlLine.RTS);
-			if((status & GCL_CTS) == 0) set.add(ControlLine.CTS);
-			if(dtr) set.add(ControlLine.DTR);
-			if((status & GCL_DSR) == 0) set.add(ControlLine.DSR);
-			if((status & GCL_CD) == 0) set.add(ControlLine.CD);
-			if((status & GCL_RI) == 0) set.add(ControlLine.RI);
-			return set;
-		}
+        @Override
+        public EnumSet<ControlLine> getControlLines() throws IOException {
+            int status = getStatus();
+            EnumSet<ControlLine> set = EnumSet.noneOf(ControlLine.class);
+            if(rts) set.add(ControlLine.RTS);
+            if((status & GCL_CTS) == 0) set.add(ControlLine.CTS);
+            if(dtr) set.add(ControlLine.DTR);
+            if((status & GCL_DSR) == 0) set.add(ControlLine.DSR);
+            if((status & GCL_CD) == 0) set.add(ControlLine.CD);
+            if((status & GCL_RI) == 0) set.add(ControlLine.RI);
+            return set;
+        }
 
-		@Override
-		public EnumSet<ControlLine> getSupportedControlLines() throws IOException {
-			return EnumSet.allOf(ControlLine.class);
-		}
+        @Override
+        public EnumSet<ControlLine> getSupportedControlLines() throws IOException {
+            return EnumSet.allOf(ControlLine.class);
+        }
 
-		@Override
-		public void setBreak(boolean value) throws IOException {
-			byte[] req = new byte[2];
-			if(controlIn(0x95, 0x1805, 0, req) < 0) {
-				throw new IOException("Error getting BREAK condition");
-			}
-			if(value) {
-				req[0] &= ~1;
-				req[1] &= ~0x40;
-			} else {
-				req[0] |= 1;
-				req[1] |= 0x40;
-			}
-			int val = (req[1] & 0xff) << 8 | (req[0] & 0xff);
-			if(controlOut(0x9a, 0x1805, val) < 0) {
-				throw new IOException("Error setting BREAK condition");
-			}
-		}
-	}
+        @Override
+        public void setBreak(boolean value) throws IOException {
+            byte[] req = new byte[2];
+            if(controlIn(0x95, 0x1805, 0, req) < 0) {
+                throw new IOException("Error getting BREAK condition");
+            }
+            if(value) {
+                req[0] &= ~1;
+                req[1] &= ~0x40;
+            } else {
+                req[0] |= 1;
+                req[1] |= 0x40;
+            }
+            int val = (req[1] & 0xff) << 8 | (req[0] & 0xff);
+            if(controlOut(0x9a, 0x1805, val) < 0) {
+                throw new IOException("Error setting BREAK condition");
+            }
+        }
+    }
 
-	@SuppressWarnings({"unused"})
-	public static Map<Integer, int[]> getSupportedDevices() {
-		final Map<Integer, int[]> supportedDevices = new LinkedHashMap<>();
-		supportedDevices.put(UsbId.VENDOR_QINHENG, new int[]{
-				UsbId.QINHENG_CH340,
-				UsbId.QINHENG_CH341A,
-		});
-		return supportedDevices;
-	}
+    @SuppressWarnings({"unused"})
+    public static Map<Integer, int[]> getSupportedDevices() {
+        final Map<Integer, int[]> supportedDevices = new LinkedHashMap<>();
+        supportedDevices.put(UsbId.VENDOR_QINHENG, new int[]{
+                UsbId.QINHENG_CH340,
+                UsbId.QINHENG_CH341A,
+        });
+        return supportedDevices;
+    }
 
 }

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/ChromeCcdSerialDriver.java

@@ -0,0 +1,91 @@
+package com.hoho.android.usbserial.driver;
+
+import android.hardware.usb.UsbConstants;
+import android.hardware.usb.UsbDevice;
+import android.hardware.usb.UsbEndpoint;
+import android.hardware.usb.UsbInterface;
+import android.util.Log;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.ArrayList;
+
+public class ChromeCcdSerialDriver implements UsbSerialDriver{
+
+    private final String TAG = ChromeCcdSerialDriver.class.getSimpleName();
+
+    private final UsbDevice mDevice;
+    private final List<UsbSerialPort> mPorts;
+
+    @Override
+    public UsbDevice getDevice() {
+        return mDevice;
+    }
+
+    @Override
+    public List<UsbSerialPort> getPorts() {
+        return mPorts;
+    }
+
+    public ChromeCcdSerialDriver(UsbDevice mDevice) {
+        this.mDevice = mDevice;
+        mPorts = new ArrayList<UsbSerialPort>();
+        for (int i = 0; i < 3; i++)
+            mPorts.add(new ChromeCcdSerialPort(mDevice, i));
+    }
+
+    public class ChromeCcdSerialPort extends CommonUsbSerialPort {
+        private UsbInterface mDataInterface;
+
+        public ChromeCcdSerialPort(UsbDevice device, int portNumber) {
+            super(device, portNumber);
+        }
+
+        @Override
+        protected void openInt() throws IOException {
+            Log.d(TAG, "claiming interfaces, count=" + mDevice.getInterfaceCount());
+            mDataInterface = mDevice.getInterface(mPortNumber);
+            if (!mConnection.claimInterface(mDataInterface, true)) {
+                throw new IOException("Could not claim shared control/data interface");
+            }
+            Log.d(TAG, "endpoint count=" + mDataInterface.getEndpointCount());
+            for (int i = 0; i < mDataInterface.getEndpointCount(); ++i) {
+                UsbEndpoint ep = mDataInterface.getEndpoint(i);
+                if ((ep.getDirection() == UsbConstants.USB_DIR_IN) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
+                    mReadEndpoint = ep;
+                } else if ((ep.getDirection() == UsbConstants.USB_DIR_OUT) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
+                    mWriteEndpoint = ep;
+                }
+            }
+        }
+
+        @Override
+        protected void closeInt() {
+            try {
+                mConnection.releaseInterface(mDataInterface);
+            } catch(Exception ignored) {}
+        }
+
+        @Override
+        public UsbSerialDriver getDriver() {
+            return ChromeCcdSerialDriver.this;
+        }
+
+        @Override
+        public void setParameters(int baudRate, int dataBits, int stopBits, int parity) throws IOException {
+            throw new UnsupportedOperationException();
+        }
+    }
+
+    public static Map<Integer, int[]> getSupportedDevices() {
+        final Map<Integer, int[]> supportedDevices = new LinkedHashMap<>();
+        supportedDevices.put(UsbId.VENDOR_GOOGLE, new int[]{
+                UsbId.GOOGLE_CR50,
+        });
+        return supportedDevices;
+    }
+}

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CommonUsbSerialPort.java

@@ -10,6 +10,7 @@ import android.hardware.usb.UsbDevice;
 import android.hardware.usb.UsbDeviceConnection;
 import android.hardware.usb.UsbEndpoint;
 import android.hardware.usb.UsbRequest;
+import android.os.Build;
 import android.util.Log;
 
 import com.hoho.android.usbserial.util.MonotonicClock;
@@ -28,16 +29,17 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
     public static boolean DEBUG = false;
 
     private static final String TAG = CommonUsbSerialPort.class.getSimpleName();
-    private static final int MAX_READ_SIZE = 16 * 1024; // = old bulkTransfer limit
+    private static final int MAX_READ_SIZE = 16 * 1024; // = old bulkTransfer limit prior to Android 9
 
     protected final UsbDevice mDevice;
     protected final int mPortNumber;
 
     // non-null when open()
-    protected UsbDeviceConnection mConnection = null;
+    protected UsbDeviceConnection mConnection;
     protected UsbEndpoint mReadEndpoint;
     protected UsbEndpoint mWriteEndpoint;
     protected UsbRequest mUsbRequest;
+    protected FlowControl mFlowControl = FlowControl.NONE;
 
     /**
      * Internal write buffer.
@@ -117,6 +119,7 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
             throw new IllegalArgumentException("Connection is null");
         }
         mConnection = connection;
+        boolean ok = false;
         try {
             openInt();
             if (mReadEndpoint == null || mWriteEndpoint == null) {
@@ -124,11 +127,13 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
             }
             mUsbRequest = new UsbRequest();
             mUsbRequest.initialize(mConnection, mReadEndpoint);
-        } catch(Exception e) {
-            try {
-                close();
-            } catch(Exception ignored) {}
-            throw e;
+            ok = true;
+        } finally {
+            if (!ok) {
+                try {
+                    close();
+                } catch (Exception ignored) {}
+            }
         }
     }
 
@@ -139,10 +144,11 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
         if (mConnection == null) {
             throw new IOException("Already closed");
         }
-        try {
-            mUsbRequest.cancel();
-        } catch(Exception ignored) {}
+        UsbRequest usbRequest = mUsbRequest;
         mUsbRequest = null;
+        try {
+            usbRequest.cancel();
+        } catch(Exception ignored) {}
         try {
             closeInt();
         } catch(Exception ignored) {}
@@ -157,25 +163,40 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
     /**
      * use simple USB request supported by all devices to test if connection is still valid
      */
-    protected void testConnection() throws IOException {
+    protected void testConnection(boolean full) throws IOException {
+        testConnection(full, "USB get_status request failed");
+    }
+
+    protected void testConnection(boolean full, String msg) throws IOException {
+        if(mUsbRequest == null) {
+            throw new IOException("Connection closed");
+        }
+        if(!full) {
+            return;
+        }
         byte[] buf = new byte[2];
         int len = mConnection.controlTransfer(0x80 /*DEVICE*/, 0 /*GET_STATUS*/, 0, 0, buf, buf.length, 200);
         if(len < 0)
-            throw new IOException("USB get_status request failed");
+            throw new IOException(msg);
     }
 
     @Override
     public int read(final byte[] dest, final int timeout) throws IOException {
-        return read(dest, timeout, true);
+        if(dest.length == 0) {
+            throw new IllegalArgumentException("Read buffer too small");
+        }
+        return read(dest, dest.length, timeout);
     }
 
-    protected int read(final byte[] dest, final int timeout, boolean testConnection) throws IOException {
-        if(mConnection == null) {
-            throw new IOException("Connection closed");
-        }
-        if(dest.length <= 0) {
-            throw new IllegalArgumentException("Read buffer to small");
+    @Override
+    public int read(final byte[] dest, final int length, final int timeout) throws IOException {return read(dest, length, timeout, true);}
+
+    protected int read(final byte[] dest, int length, final int timeout, boolean testConnection) throws IOException {
+        testConnection(false);
+        if(length <= 0) {
+            throw new IllegalArgumentException("Read length too small");
         }
+        length = Math.min(length, dest.length);
         final int nread;
         if (timeout != 0) {
             // bulkTransfer will cause data loss with short timeout + high baud rates + continuous transfer
@@ -187,16 +208,16 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
             //     /system/lib64/libandroid_runtime.so (android_hardware_UsbDeviceConnection_request_wait(_JNIEnv*, _jobject*, long)+84)
             // data loss / crashes were observed with timeout up to 200 msec
             long endTime = testConnection ? MonotonicClock.millis() + timeout : 0;
-            int readMax = Math.min(dest.length, MAX_READ_SIZE);
+            int readMax = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) ? length : Math.min(length, MAX_READ_SIZE);
             nread = mConnection.bulkTransfer(mReadEndpoint, dest, readMax, timeout);
             // Android error propagation is improvable:
             //  nread == -1 can be: timeout, connection lost, buffer to small, ???
-            if(nread == -1 && testConnection && MonotonicClock.millis() < endTime)
-                testConnection();
+            if(nread == -1 && testConnection)
+                testConnection(MonotonicClock.millis() < endTime);
 
         } else {
-            final ByteBuffer buf = ByteBuffer.wrap(dest);
-            if (!mUsbRequest.queue(buf, dest.length)) {
+            final ByteBuffer buf = ByteBuffer.wrap(dest, 0, length);
+            if (!mUsbRequest.queue(buf, length)) {
                 throw new IOException("Queueing USB request failed");
             }
             final UsbRequest response = mConnection.requestWait();
@@ -207,21 +228,23 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
             // Android error propagation is improvable:
             //   response != null & nread == 0 can be: connection lost, buffer to small, ???
             if(nread == 0) {
-                testConnection();
+                testConnection(true);
             }
         }
         return Math.max(nread, 0);
     }
 
     @Override
-    public void write(final byte[] src, final int timeout) throws IOException {
-        int offset = 0;
-        final long endTime = (timeout == 0) ? 0 : (MonotonicClock.millis() + timeout);
+    public void write(byte[] src, int timeout) throws IOException {write(src, src.length, timeout);}
 
-        if(mConnection == null) {
-            throw new IOException("Connection closed");
-        }
-        while (offset < src.length) {
+    @Override
+    public void write(final byte[] src, int length, final int timeout) throws IOException {
+        int offset = 0;
+        long startTime = MonotonicClock.millis();
+        length = Math.min(length, src.length);
+
+        testConnection(false);
+        while (offset < length) {
             int requestTimeout;
             final int requestLength;
             final int actualLength;
@@ -232,7 +255,7 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
                 if (mWriteBuffer == null) {
                     mWriteBuffer = new byte[mWriteEndpoint.getMaxPacketSize()];
                 }
-                requestLength = Math.min(src.length - offset, mWriteBuffer.length);
+                requestLength = Math.min(length - offset, mWriteBuffer.length);
                 if (offset == 0) {
                     writeBuffer = src;
                 } else {
@@ -243,7 +266,7 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
                 if (timeout == 0 || offset == 0) {
                     requestTimeout = timeout;
                 } else {
-                    requestTimeout = (int)(endTime - MonotonicClock.millis());
+                    requestTimeout = (int)(startTime + timeout - MonotonicClock.millis());
                     if(requestTimeout == 0)
                         requestTimeout = -1;
                 }
@@ -253,16 +276,19 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
                     actualLength = mConnection.bulkTransfer(mWriteEndpoint, writeBuffer, requestLength, requestTimeout);
                 }
             }
+            long elapsed = MonotonicClock.millis() - startTime;
             if (DEBUG) {
-                Log.d(TAG, "Wrote " + actualLength + "/" + requestLength + " offset " + offset + "/" + src.length + " timeout " + requestTimeout);
+                Log.d(TAG, "Wrote " + actualLength + "/" + requestLength + " offset " + offset + "/" + length + " time " + elapsed + "/" + requestTimeout);
             }
             if (actualLength <= 0) {
-                if (timeout != 0 && MonotonicClock.millis() >= endTime) {
-                    SerialTimeoutException ex = new SerialTimeoutException("Error writing " + requestLength + " bytes at offset " + offset + " of total " + src.length + ", rc=" + actualLength);
-                    ex.bytesTransferred = offset;
-                    throw ex;
+                String msg = "Error writing " + requestLength + " bytes at offset " + offset + " of total " + src.length + " after " + elapsed + "msec, rc=" + actualLength;
+                if (timeout != 0) {
+                    // could be buffer full because: writing to fast, stopped by flow control
+                    testConnection(elapsed < timeout, msg);
+                    throw new SerialTimeoutException(msg, offset);
                 } else {
-                    throw new IOException("Error writing " + requestLength + " bytes at offset " + offset + " of total " + src.length);
+                    throw new IOException(msg);
+
                 }
             }
             offset += actualLength;
@@ -271,7 +297,7 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
 
     @Override
     public boolean isOpen() {
-        return mConnection != null;
+        return mUsbRequest != null;
     }
 
     @Override
@@ -302,16 +328,29 @@ public abstract class CommonUsbSerialPort implements UsbSerialPort {
     public void setRTS(boolean value) throws IOException { throw new UnsupportedOperationException(); }
 
     @Override
-    public abstract EnumSet<ControlLine> getControlLines() throws IOException;
+    public EnumSet<ControlLine> getControlLines() throws IOException { throw new UnsupportedOperationException(); }
 
     @Override
-    public abstract EnumSet<ControlLine> getSupportedControlLines() throws IOException;
+    public EnumSet<ControlLine> getSupportedControlLines() throws IOException { return EnumSet.noneOf(ControlLine.class); }
 
     @Override
-    public void purgeHwBuffers(boolean purgeWriteBuffers, boolean purgeReadBuffers) throws IOException {
-        throw new UnsupportedOperationException();
+    public void setFlowControl(FlowControl flowcontrol) throws IOException {
+        if (flowcontrol != FlowControl.NONE)
+            throw new UnsupportedOperationException();
     }
 
+    @Override
+    public FlowControl getFlowControl() { return mFlowControl; }
+
+    @Override
+    public EnumSet<FlowControl> getSupportedFlowControl() { return EnumSet.of(FlowControl.NONE); }
+
+    @Override
+    public boolean getXON() throws IOException { throw new UnsupportedOperationException(); }
+
+    @Override
+    public void purgeHwBuffers(boolean purgeWriteBuffers, boolean purgeReadBuffers) throws IOException { throw new UnsupportedOperationException(); }
+
     @Override
     public void setBreak(boolean value) throws IOException { throw new UnsupportedOperationException(); }
 

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/Cp21xxSerialDriver.java

@@ -60,9 +60,14 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
         private static final int SILABSER_SET_LINE_CTL_REQUEST_CODE = 0x03;
         private static final int SILABSER_SET_BREAK_REQUEST_CODE = 0x05;
         private static final int SILABSER_SET_MHS_REQUEST_CODE = 0x07;
-        private static final int SILABSER_SET_BAUDRATE = 0x1E;
-        private static final int SILABSER_FLUSH_REQUEST_CODE = 0x12;
         private static final int SILABSER_GET_MDMSTS_REQUEST_CODE = 0x08;
+        private static final int SILABSER_SET_XON_REQUEST_CODE = 0x09;
+        private static final int SILABSER_SET_XOFF_REQUEST_CODE = 0x0A;
+        private static final int SILABSER_GET_COMM_STATUS_REQUEST_CODE = 0x10;
+        private static final int SILABSER_FLUSH_REQUEST_CODE = 0x12;
+        private static final int SILABSER_SET_FLOW_REQUEST_CODE = 0x13;
+        private static final int SILABSER_SET_CHARS_REQUEST_CODE = 0x19;
+        private static final int SILABSER_SET_BAUDRATE_REQUEST_CODE = 0x1E;
 
         private static final int FLUSH_READ_CODE = 0x0a;
         private static final int FLUSH_WRITE_CODE = 0x05;
@@ -84,6 +89,8 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
         /*
         * SILABSER_GET_MDMSTS_REQUEST_CODE
          */
+        private static final int STATUS_DTR = 0x01;
+        private static final int STATUS_RTS = 0x02;
         private static final int STATUS_CTS = 0x10;
         private static final int STATUS_DSR = 0x20;
         private static final int STATUS_RI = 0x40;
@@ -118,7 +125,7 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
             byte[] buffer = new byte[1];
             int result = mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, SILABSER_GET_MDMSTS_REQUEST_CODE, 0,
                     mPortNumber, buffer, buffer.length, USB_WRITE_TIMEOUT_MILLIS);
-            if (result != 1) {
+            if (result != buffer.length) {
                 throw new IOException("Control transfer failed: " + SILABSER_GET_MDMSTS_REQUEST_CODE + " / " + 0 + " -> " + result);
             }
             return buffer[0];
@@ -147,6 +154,7 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
 
             setConfigSingle(SILABSER_IFC_ENABLE_REQUEST_CODE, UART_ENABLE);
             setConfigSingle(SILABSER_SET_MHS_REQUEST_CODE, (dtr ? DTR_ENABLE : DTR_DISABLE) | (rts ? RTS_ENABLE : RTS_DISABLE));
+            setFlowControl(mFlowControl);
         }
 
         @Override
@@ -166,7 +174,7 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
                     (byte) ((baudRate >> 16) & 0xff),
                     (byte) ((baudRate >> 24) & 0xff)
             };
-            int ret = mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, SILABSER_SET_BAUDRATE,
+            int ret = mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, SILABSER_SET_BAUDRATE_REQUEST_CODE,
                     0, mPortNumber, data, 4, USB_WRITE_TIMEOUT_MILLIS);
             if (ret < 0) {
                 throw new IOException("Error setting baud rate");
@@ -289,9 +297,11 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
         public EnumSet<ControlLine> getControlLines() throws IOException {
             byte status = getStatus();
             EnumSet<ControlLine> set = EnumSet.noneOf(ControlLine.class);
-            if(rts) set.add(ControlLine.RTS);
+            //if(rts) set.add(ControlLine.RTS);                      // configured value
+            if((status & STATUS_RTS) != 0) set.add(ControlLine.RTS); // actual value
             if((status & STATUS_CTS) != 0) set.add(ControlLine.CTS);
-            if(dtr) set.add(ControlLine.DTR);
+            //if(dtr) set.add(ControlLine.DTR);                      // configured value
+            if((status & STATUS_DTR) != 0) set.add(ControlLine.DTR); // actual value
             if((status & STATUS_DSR) != 0) set.add(ControlLine.DSR);
             if((status & STATUS_CD) != 0) set.add(ControlLine.CD);
             if((status & STATUS_RI) != 0) set.add(ControlLine.RI);
@@ -303,6 +313,73 @@ public class Cp21xxSerialDriver implements UsbSerialDriver {
             return EnumSet.allOf(ControlLine.class);
         }
 
+        @Override
+        public boolean getXON() throws IOException {
+            byte[] buffer = new byte[0x13];
+            int result = mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, SILABSER_GET_COMM_STATUS_REQUEST_CODE, 0,
+                    mPortNumber, buffer, buffer.length, USB_WRITE_TIMEOUT_MILLIS);
+            if (result != buffer.length) {
+                throw new IOException("Control transfer failed: " + SILABSER_GET_COMM_STATUS_REQUEST_CODE + " -> " + result);
+            }
+            return (buffer[4] & 8) == 0;
+        }
+
+        /**
+         * emulate external XON/OFF
+         * @throws IOException
+         */
+        public void setXON(boolean value) throws IOException {
+            setConfigSingle(value ? SILABSER_SET_XON_REQUEST_CODE : SILABSER_SET_XOFF_REQUEST_CODE, 0);
+        }
+
+        @Override
+        public void setFlowControl(FlowControl flowControl) throws IOException {
+            byte[] data = new byte[16];
+            if(flowControl == FlowControl.RTS_CTS) {
+                data[4] |=  0b1000_0000; // RTS
+                data[0] |=  0b0000_1000; // CTS
+            } else {
+                if(rts)
+                    data[4] |= 0b0100_0000;
+            }
+            if(flowControl == FlowControl.DTR_DSR) {
+                data[0] |= 0b0000_0010; // DTR
+                data[0] |= 0b0001_0000; // DSR
+            } else {
+                if(dtr)
+                    data[0] |= 0b0000_0001;
+            }
+            if(flowControl == FlowControl.XON_XOFF) {
+                byte[] chars = new byte[]{0, 0, 0, 0, CHAR_XON, CHAR_XOFF};
+                int ret = mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, SILABSER_SET_CHARS_REQUEST_CODE,
+                        0, mPortNumber, chars, chars.length, USB_WRITE_TIMEOUT_MILLIS);
+                if (ret != chars.length) {
+                    throw new IOException("Error setting XON/XOFF chars");
+                }
+                data[4] |= 0b0000_0011;
+                data[7] |= 0b1000_0000;
+                data[8] = (byte)128;
+                data[12] = (byte)128;
+            }
+            if(flowControl == FlowControl.XON_XOFF_INLINE) {
+                throw new UnsupportedOperationException();
+            }
+            int ret = mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, SILABSER_SET_FLOW_REQUEST_CODE,
+                    0, mPortNumber, data, data.length, USB_WRITE_TIMEOUT_MILLIS);
+            if (ret != data.length) {
+                throw new IOException("Error setting flow control");
+            }
+            if(flowControl == FlowControl.XON_XOFF) {
+                setXON(true);
+            }
+            mFlowControl = flowControl;
+        }
+
+        @Override
+        public EnumSet<FlowControl> getSupportedFlowControl() {
+            return EnumSet.of(FlowControl.NONE, FlowControl.RTS_CTS, FlowControl.DTR_DSR, FlowControl.XON_XOFF);
+        }
+
         @Override
         // note: only working on some devices, on other devices ignored w/o error
         public void purgeHwBuffers(boolean purgeWriteBuffers, boolean purgeReadBuffers) throws IOException {

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/FtdiSerialDriver.java

@@ -64,6 +64,7 @@ public class FtdiSerialDriver implements UsbSerialDriver {
 
         private static final int RESET_REQUEST = 0;
         private static final int MODEM_CONTROL_REQUEST = 1;
+        private static final int SET_FLOW_CONTROL_REQUEST = 2;
         private static final int SET_BAUD_RATE_REQUEST = 3;
         private static final int SET_DATA_REQUEST = 4;
         private static final int GET_MODEM_STATUS_REQUEST = 5;
@@ -120,6 +121,7 @@ public class FtdiSerialDriver implements UsbSerialDriver {
             if (result != 0) {
                 throw new IOException("Init RTS,DTR failed: result=" + result);
             }
+            setFlowControl(mFlowControl);
 
             // mDevice.getVersion() would require API 23
             byte[] rawDescriptors = mConnection.getRawDescriptors();
@@ -139,24 +141,37 @@ public class FtdiSerialDriver implements UsbSerialDriver {
         }
 
         @Override
-        public int read(final byte[] dest, final int timeout) throws IOException {
+        public int read(final byte[] dest, final int timeout) throws IOException
+        {
             if(dest.length <= READ_HEADER_LENGTH) {
-                throw new IllegalArgumentException("Read buffer to small");
+                throw new IllegalArgumentException("Read buffer too small");
                 // could allocate larger buffer, including space for 2 header bytes, but this would
                 // result in buffers not being 64 byte aligned any more, causing data loss at continuous
                 // data transfer at high baud rates when buffers are fully filled.
             }
+            return read(dest, dest.length, timeout);
+        }
+
+        @Override
+        public int read(final byte[] dest, int length, final int timeout) throws IOException {
+            if(length <= READ_HEADER_LENGTH) {
+                throw new IllegalArgumentException("Read length too small");
+                // could allocate larger buffer, including space for 2 header bytes, but this would
+                // result in buffers not being 64 byte aligned any more, causing data loss at continuous
+                // data transfer at high baud rates when buffers are fully filled.
+            }
+            length = Math.min(length, dest.length);
             int nread;
             if (timeout != 0) {
                 long endTime = MonotonicClock.millis() + timeout;
                 do {
-                    nread = super.read(dest, Math.max(1, (int)(endTime - MonotonicClock.millis())), false);
+                    nread = super.read(dest, length, Math.max(1, (int)(endTime - MonotonicClock.millis())), false);
                 } while (nread == READ_HEADER_LENGTH && MonotonicClock.millis() < endTime);
-                if(nread <= 0 && MonotonicClock.millis() < endTime)
-                    testConnection();
+                if(nread <= 0)
+                    testConnection(MonotonicClock.millis() < endTime);
             } else {
                 do {
-                    nread = super.read(dest, timeout, false);
+                    nread = super.read(dest, length, timeout);
                 } while (nread == READ_HEADER_LENGTH);
             }
             return readFilter(dest, nread);
@@ -290,7 +305,7 @@ public class FtdiSerialDriver implements UsbSerialDriver {
             byte[] data = new byte[2];
             int result = mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, GET_MODEM_STATUS_REQUEST,
                     0, mPortNumber+1, data, data.length, USB_WRITE_TIMEOUT_MILLIS);
-            if (result != 2) {
+            if (result != data.length) {
                 throw new IOException("Get modem status failed: result=" + result);
             }
             return data[0];
@@ -364,6 +379,38 @@ public class FtdiSerialDriver implements UsbSerialDriver {
             return EnumSet.allOf(ControlLine.class);
         }
 
+        @Override
+        public void setFlowControl(FlowControl flowControl) throws IOException {
+            int value = 0;
+            int index = mPortNumber+1;
+            switch (flowControl) {
+                case NONE:
+                    break;
+                case RTS_CTS:
+                    index |= 0x100;
+                    break;
+                case DTR_DSR:
+                    index |= 0x200;
+                    break;
+                case XON_XOFF_INLINE:
+                    value = CHAR_XON + (CHAR_XOFF << 8);
+                    index |= 0x400;
+                    break;
+                default:
+                    throw new UnsupportedOperationException();
+            }
+            int result = mConnection.controlTransfer(REQTYPE_HOST_TO_DEVICE, SET_FLOW_CONTROL_REQUEST,
+                    value, index, null, 0, USB_WRITE_TIMEOUT_MILLIS);
+            if (result != 0)
+                throw new IOException("Set flow control failed: result=" + result);
+            mFlowControl = flowControl;
+        }
+
+        @Override
+        public EnumSet<FlowControl> getSupportedFlowControl() {
+            return EnumSet.of(FlowControl.NONE, FlowControl.RTS_CTS, FlowControl.DTR_DSR, FlowControl.XON_XOFF_INLINE);
+        }
+
         @Override
         public void purgeHwBuffers(boolean purgeWriteBuffers, boolean purgeReadBuffers) throws IOException {
             if (purgeWriteBuffers) {
@@ -406,7 +453,7 @@ public class FtdiSerialDriver implements UsbSerialDriver {
             byte[] data = new byte[1];
             int result = mConnection.controlTransfer(REQTYPE_DEVICE_TO_HOST, GET_LATENCY_TIMER_REQUEST,
                     0, mPortNumber+1, data, data.length, USB_WRITE_TIMEOUT_MILLIS);
-            if (result != 1) {
+            if (result != data.length) {
                 throw new IOException("Get latency timer failed: result=" + result);
             }
             return data[0];

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/GsmModemSerialDriver.java

@@ -0,0 +1,102 @@
+package com.hoho.android.usbserial.driver;
+
+import android.hardware.usb.UsbConstants;
+import android.hardware.usb.UsbDevice;
+import android.hardware.usb.UsbEndpoint;
+import android.hardware.usb.UsbInterface;
+import android.util.Log;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+public class GsmModemSerialDriver implements UsbSerialDriver{
+
+    private final String TAG = GsmModemSerialDriver.class.getSimpleName();
+
+    private final UsbDevice mDevice;
+    private final UsbSerialPort mPort;
+
+    @Override
+    public UsbDevice getDevice() {
+        return mDevice;
+    }
+
+    @Override
+    public List<UsbSerialPort> getPorts() {
+        return Collections.singletonList(mPort);
+    }
+
+    public GsmModemSerialDriver(UsbDevice mDevice) {
+        this.mDevice = mDevice;
+        mPort = new GsmModemSerialPort(mDevice, 0);
+    }
+
+    public class GsmModemSerialPort extends CommonUsbSerialPort {
+
+        private UsbInterface mDataInterface;
+
+        public GsmModemSerialPort(UsbDevice device, int portNumber) {
+            super(device, portNumber);
+        }
+
+        @Override
+        protected void openInt() throws IOException {
+            Log.d(TAG, "claiming interfaces, count=" + mDevice.getInterfaceCount());
+            mDataInterface = mDevice.getInterface(0);
+            if (!mConnection.claimInterface(mDataInterface, true)) {
+                throw new IOException("Could not claim shared control/data interface");
+            }
+            Log.d(TAG, "endpoint count=" + mDataInterface.getEndpointCount());
+            for (int i = 0; i < mDataInterface.getEndpointCount(); ++i) {
+                UsbEndpoint ep = mDataInterface.getEndpoint(i);
+                if ((ep.getDirection() == UsbConstants.USB_DIR_IN) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
+                    mReadEndpoint = ep;
+                } else if ((ep.getDirection() == UsbConstants.USB_DIR_OUT) && (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK)) {
+                    mWriteEndpoint = ep;
+                }
+            }
+            initGsmModem();
+        }
+
+        @Override
+        protected void closeInt() {
+            try {
+                mConnection.releaseInterface(mDataInterface);
+            } catch(Exception ignored) {}
+
+        }
+
+        private int initGsmModem() throws IOException {
+            int len = mConnection.controlTransfer(
+                    0x21, 0x22, 0x01, 0, null, 0, 5000);
+            if(len < 0) {
+                throw new IOException("init failed");
+            }
+            return len;
+        }
+
+        @Override
+        public UsbSerialDriver getDriver() {
+            return GsmModemSerialDriver.this;
+        }
+
+        @Override
+        public void setParameters(int baudRate, int dataBits, int stopBits, int parity) throws IOException {
+            throw new UnsupportedOperationException();
+        }
+
+    }
+
+    public static Map<Integer, int[]> getSupportedDevices() {
+        final Map<Integer, int[]> supportedDevices = new LinkedHashMap<>();
+        supportedDevices.put(UsbId.VENDOR_UNISOC, new int[]{
+                UsbId.FIBOCOM_L610,
+                UsbId.FIBOCOM_L612,
+        });
+        return supportedDevices;
+    }
+}

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/ProlificSerialDriver.java

@@ -122,7 +122,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
         private volatile Thread mReadStatusThread = null;
         private final Object mReadStatusThreadLock = new Object();
         private boolean mStopReadStatusThread = false;
-        private IOException mReadStatusException = null;
+        private Exception mReadStatusException = null;
 
 
         public ProlificSerialPort(UsbDevice device, int portNumber) {
@@ -201,12 +201,12 @@ public class ProlificSerialDriver implements UsbSerialDriver {
 
         private void readStatusThreadFunction() {
             try {
+                byte[] buffer = new byte[STATUS_BUFFER_SIZE];
                 while (!mStopReadStatusThread) {
-                    byte[] buffer = new byte[STATUS_BUFFER_SIZE];
                     long endTime = MonotonicClock.millis() + 500;
                     int readBytesCount = mConnection.bulkTransfer(mInterruptEndpoint, buffer, STATUS_BUFFER_SIZE, 500);
-                    if(readBytesCount == -1 && MonotonicClock.millis() < endTime)
-                        testConnection();
+                    if(readBytesCount == -1)
+                        testConnection(MonotonicClock.millis() < endTime);
                     if (readBytesCount > 0) {
                         if (readBytesCount != STATUS_BUFFER_SIZE) {
                             throw new IOException("Invalid status notification, expected " + STATUS_BUFFER_SIZE + " bytes, got " + readBytesCount);
@@ -217,8 +217,9 @@ public class ProlificSerialDriver implements UsbSerialDriver {
                         }
                     }
                 }
-            } catch (IOException e) {
-                mReadStatusException = e;
+            } catch (Exception e) {
+                if (isOpen())
+                    mReadStatusException = e;
             }
             //Log.d(TAG, "end control line status thread " + mStopReadStatusThread + " " + (mReadStatusException == null ? "-" : mReadStatusException.getMessage()));
         }
@@ -249,8 +250,8 @@ public class ProlificSerialDriver implements UsbSerialDriver {
                 }
             }
 
-            /* throw and clear an exception which occured in the status read thread */
-            IOException readStatusException = mReadStatusException;
+            /* throw and clear an exception which occurred in the status read thread */
+            Exception readStatusException = mReadStatusException;
             if (mReadStatusException != null) {
                 mReadStatusException = null;
                 throw new IOException(readStatusException);
@@ -314,6 +315,7 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             resetDevice();
             doBlackMagic();
             setControlLines(mControlLinesValue);
+            setFlowControl(mFlowControl);
         }
 
         @Override
@@ -525,7 +527,6 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             setControlLines(newControlLinesValue);
         }
 
-
         @Override
         public EnumSet<ControlLine> getControlLines() throws IOException {
             int status = getStatus();
@@ -544,6 +545,39 @@ public class ProlificSerialDriver implements UsbSerialDriver {
             return EnumSet.allOf(ControlLine.class);
         }
 
+        @Override
+        public void setFlowControl(FlowControl flowControl) throws IOException {
+            // vendorOut values from https://www.mail-archive.com/linux-usb@vger.kernel.org/msg110968.html
+            switch (flowControl) {
+                case NONE:
+                    if (mDeviceType == DeviceType.DEVICE_TYPE_HXN)
+                        vendorOut(0x0a, 0xff, null);
+                    else
+                        vendorOut(0, 0, null);
+                    break;
+                case RTS_CTS:
+                    if (mDeviceType == DeviceType.DEVICE_TYPE_HXN)
+                        vendorOut(0x0a, 0xfa, null);
+                    else
+                        vendorOut(0, 0x61, null);
+                    break;
+                case XON_XOFF_INLINE:
+                    if (mDeviceType == DeviceType.DEVICE_TYPE_HXN)
+                        vendorOut(0x0a, 0xee, null);
+                    else
+                        vendorOut(0, 0xc1, null);
+                    break;
+                default:
+                    throw new UnsupportedOperationException();
+            }
+            mFlowControl = flowControl;
+        }
+
+        @Override
+        public EnumSet<FlowControl> getSupportedFlowControl() {
+            return EnumSet.of(FlowControl.NONE, FlowControl.RTS_CTS, FlowControl.XON_XOFF_INLINE);
+        }
+
         @Override
         public void purgeHwBuffers(boolean purgeWriteBuffers, boolean purgeReadBuffers) throws IOException {
             if (mDeviceType == DeviceType.DEVICE_TYPE_HXN) {

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/SerialTimeoutException.java

@@ -9,7 +9,8 @@ import java.io.InterruptedIOException;
  * {@see InterruptedIOException#bytesTransferred} may contain bytes transferred
  */
 public class SerialTimeoutException extends InterruptedIOException {
-    public SerialTimeoutException(String s) {
+    public SerialTimeoutException(String s, int bytesTransferred) {
         super(s);
+        this.bytesTransferred = bytesTransferred;
     }
 }

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/UsbId.java

@@ -37,10 +37,17 @@ public final class UsbId {
     public static final int PROLIFIC_PL2303GE = 0x23e3; // "
     public static final int PROLIFIC_PL2303GS = 0x23f3; // "
 
+    public static final int VENDOR_GOOGLE = 0x18d1;
+    public static final int GOOGLE_CR50 = 0x5014;
+
     public static final int VENDOR_QINHENG = 0x1a86;
     public static final int QINHENG_CH340 = 0x7523;
     public static final int QINHENG_CH341A = 0x5523;
 
+    public static final int VENDOR_UNISOC = 0x1782;
+    public static final int FIBOCOM_L610 = 0x4D10;
+    public static final int FIBOCOM_L612 = 0x4D12;
+
 
     private UsbId() {
         throw new IllegalAccessError("Non-instantiable class");

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/UsbSerialPort.java

@@ -58,7 +58,16 @@ public interface UsbSerialPort extends Closeable {
     int STOPBITS_2 = 2;
 
     /** Values for get[Supported]ControlLines() */
-    enum ControlLine { RTS, CTS,  DTR, DSR,  CD, RI }
+    enum ControlLine { RTS, CTS, DTR, DSR, CD, RI }
+
+    /** Values for (set|get|getSupported)FlowControl() */
+    enum FlowControl { NONE, RTS_CTS, DTR_DSR, XON_XOFF, XON_XOFF_INLINE }
+
+    /** XON character used with flow control XON/XOFF */
+    char CHAR_XON = 17;
+    /** XOFF character used with flow control XON/XOFF */
+    char CHAR_XOFF = 19;
+
 
     /**
      * Returns the driver used by this port.
@@ -122,6 +131,17 @@ public interface UsbSerialPort extends Closeable {
      */
     int read(final byte[] dest, final int timeout) throws IOException;
 
+    /**
+     * Reads bytes with specified length into the destination buffer.
+     *
+     * @param dest the destination byte buffer
+     * @param length the maximum length of the data to read
+     * @param timeout the timeout for reading in milliseconds, 0 is infinite
+     * @return the actual number of bytes read
+     * @throws IOException if an error occurred during reading
+     */
+    int read(final byte[] dest, int length, final int timeout) throws IOException;
+
     /**
      * Writes as many bytes as possible from the source buffer.
      *
@@ -133,6 +153,18 @@ public interface UsbSerialPort extends Closeable {
      */
     void write(final byte[] src, final int timeout) throws IOException;
 
+    /**
+     * Writes bytes with specified length from the source buffer.
+     *
+     * @param src the source byte buffer
+     * @param length the length of the data to write
+     * @param timeout the timeout for writing in milliseconds, 0 is infinite
+     * @throws SerialTimeoutException if timeout reached before sending all data.
+     *                                ex.bytesTransferred may contain bytes transferred
+     * @throws IOException if an error occurred during writing
+     */
+    void write(final byte[] src, int length, final int timeout) throws IOException;
+
     /**
      * Sets various serial port parameters.
      *
@@ -143,7 +175,7 @@ public interface UsbSerialPort extends Closeable {
      * @param parity one of {@link #PARITY_NONE}, {@link #PARITY_ODD},
      *               {@link #PARITY_EVEN}, {@link #PARITY_MARK}, or {@link #PARITY_SPACE}.
      * @throws IOException on error setting the port parameters
-     * @throws UnsupportedOperationException if values are not supported by a specific device
+     * @throws UnsupportedOperationException if not supported or values are not supported by a specific device
      */
     void setParameters(int baudRate, int dataBits, int stopBits, @Parity int parity) throws IOException;
 
@@ -225,6 +257,7 @@ public interface UsbSerialPort extends Closeable {
      *
      * @return EnumSet.contains(...) is {@code true} if set, else {@code false}
      * @throws IOException if an error occurred during reading
+     * @throws UnsupportedOperationException if not supported
      */
     EnumSet<ControlLine> getControlLines() throws IOException;
 
@@ -236,6 +269,36 @@ public interface UsbSerialPort extends Closeable {
      */
     EnumSet<ControlLine> getSupportedControlLines() throws IOException;
 
+    /**
+     * Set flow control mode, if supported
+     * @param flowControl @FlowControl
+     * @throws IOException if an error occurred during writing
+     * @throws UnsupportedOperationException if not supported
+     */
+    void setFlowControl(FlowControl flowControl) throws IOException;
+
+    /**
+     * Get flow control mode.
+     * @return FlowControl
+     */
+    FlowControl getFlowControl();
+
+    /**
+     * Get supported flow control modes
+     * @return EnumSet.contains(...) is {@code true} if supported, else {@code false}
+     */
+    EnumSet<FlowControl> getSupportedFlowControl();
+
+    /**
+     * If flow control = XON_XOFF, indicates that send is enabled by XON.
+     * Devices supporting flow control = XON_XOFF_INLINE return CHAR_XON/CHAR_XOFF in read() data.
+     *
+     * @return the current state
+     * @throws IOException if an error occurred during reading
+     * @throws UnsupportedOperationException if not supported
+     */
+    boolean getXON() throws IOException;
+
     /**
      * Purge non-transmitted output data and / or non-read input data.
      *

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/UsbSerialProber.java

@@ -37,6 +37,8 @@ public class UsbSerialProber {
         probeTable.addDriver(FtdiSerialDriver.class);
         probeTable.addDriver(ProlificSerialDriver.class);
         probeTable.addDriver(Ch34xSerialDriver.class);
+        probeTable.addDriver(GsmModemSerialDriver.class);
+        probeTable.addDriver(ChromeCcdSerialDriver.class);
         return probeTable;
     }
 

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/util/HexDump.java

@@ -19,14 +19,17 @@ package com.hoho.android.usbserial.util;
 import java.security.InvalidParameterException;
 
 /**
- * Clone of Android's HexDump class, for use in debugging. Cosmetic changes
- * only.
+ * Clone of Android's /core/java/com/android/internal/util/HexDump class, for use in debugging.
+ * Changes: space separated hex strings
  */
 public class HexDump {
     private final static char[] HEX_DIGITS = {
             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
     };
 
+    private HexDump() {
+    }
+
     public static String dumpHexString(byte[] array) {
         return dumpHexString(array, 0, array.length);
     }
@@ -82,10 +85,12 @@ public class HexDump {
     }
 
     public static String toHexString(byte[] array, int offset, int length) {
-        char[] buf = new char[length * 2];
+        char[] buf = new char[length > 0 ? length * 3 - 1 : 0];
 
         int bufIndex = 0;
         for (int i = offset; i < offset + length; i++) {
+            if (i > offset)
+                buf[bufIndex++] = ' ';
             byte b = array[i];
             buf[bufIndex++] = HEX_DIGITS[(b >>> 4) & 0x0F];
             buf[bufIndex++] = HEX_DIGITS[b & 0x0F];
@@ -139,13 +144,13 @@ public class HexDump {
         throw new InvalidParameterException("Invalid hex char '" + c + "'");
     }
 
+    /** accepts any separator, e.g. space or newline */
     public static byte[] hexStringToByteArray(String hexString) {
         int length = hexString.length();
-        byte[] buffer = new byte[length / 2];
+        byte[] buffer = new byte[(length + 1) / 3];
 
-        for (int i = 0; i < length; i += 2) {
-            buffer[i / 2] = (byte) ((toByte(hexString.charAt(i)) << 4) | toByte(hexString
-                    .charAt(i + 1)));
+        for (int i = 0; i < length; i += 3) {
+            buffer[i / 3] = (byte) ((toByte(hexString.charAt(i)) << 4) | toByte(hexString.charAt(i + 1)));
         }
 
         return buffer;

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/util/SerialInputOutputManager.java

@@ -13,16 +13,19 @@ import com.hoho.android.usbserial.driver.UsbSerialPort;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
- * Utility class which services a {@link UsbSerialPort} in its {@link #run()} method.
+ * Utility class which services a {@link UsbSerialPort} in its {@link #runWrite()} ()} and {@link #runRead()} ()} ()} methods.
  *
  * @author mike wakerly (opensource@hoho.com)
  */
-public class SerialInputOutputManager implements Runnable {
+public class SerialInputOutputManager {
 
     public enum State {
         STOPPED,
+        STARTING,
         RUNNING,
         STOPPING
     }
@@ -32,9 +35,6 @@ public class SerialInputOutputManager implements Runnable {
     private static final String TAG = SerialInputOutputManager.class.getSimpleName();
     private static final int BUFSIZ = 4096;
 
-    /**
-     * default read timeout is infinite, to avoid data loss with bulkTransfer API
-     */
     private int mReadTimeout = 0;
     private int mWriteTimeout = 0;
 
@@ -45,7 +45,8 @@ public class SerialInputOutputManager implements Runnable {
     private ByteBuffer mWriteBuffer = ByteBuffer.allocate(BUFSIZ);
 
     private int mThreadPriority = Process.THREAD_PRIORITY_URGENT_AUDIO;
-    private State mState = State.STOPPED; // Synchronized by 'this'
+    private final AtomicReference<State> mState = new AtomicReference<>(State.STOPPED);
+    private CountDownLatch mStartuplatch = new CountDownLatch(2);
     private Listener mListener; // Synchronized by 'this'
     private final UsbSerialPort mSerialPort;
 
@@ -56,7 +57,7 @@ public class SerialInputOutputManager implements Runnable {
         void onNewData(byte[] data);
 
         /**
-         * Called when {@link SerialInputOutputManager#run()} aborts due to an error.
+         * Called when {@link SerialInputOutputManager#runRead()} ()} or {@link SerialInputOutputManager#runWrite()} ()} ()} aborts due to an error.
          */
         void onRunError(Exception e);
     }
@@ -86,8 +87,9 @@ public class SerialInputOutputManager implements Runnable {
      * @param threadPriority  see {@link Process#setThreadPriority(int)}
      * */
     public void setThreadPriority(int threadPriority) {
-        if (mState != State.STOPPED)
+        if (!mState.compareAndSet(State.STOPPED, State.STOPPED)) {
             throw new IllegalStateException("threadPriority only configurable before SerialInputOutputManager is started");
+        }
         mThreadPriority = threadPriority;
     }
 
@@ -96,7 +98,7 @@ public class SerialInputOutputManager implements Runnable {
      */
     public void setReadTimeout(int timeout) {
         // when set if already running, read already blocks and the new value will not become effective now
-        if(mReadTimeout == 0 && timeout != 0 && mState != State.STOPPED)
+        if(mReadTimeout == 0 && timeout != 0 && mState.get() != State.STOPPED)
             throw new IllegalStateException("readTimeout only configurable before SerialInputOutputManager is started");
         mReadTimeout = timeout;
     }
@@ -144,79 +146,152 @@ public class SerialInputOutputManager implements Runnable {
     }
 
     /**
-     * when using writeAsync, it is recommended to use readTimeout != 0,
-     * else the write will be delayed until read data is available
+     * write data asynchronously
      */
     public void writeAsync(byte[] data) {
         synchronized (mWriteBufferLock) {
             mWriteBuffer.put(data);
+            mWriteBufferLock.notifyAll(); // Notify waiting threads
         }
     }
 
     /**
-     * start SerialInputOutputManager in separate thread
+     * start SerialInputOutputManager in separate threads
      */
     public void start() {
-        if(mState != State.STOPPED)
+        if(mState.compareAndSet(State.STOPPED, State.STARTING)) {
+            mStartuplatch = new CountDownLatch(2);
+            new Thread(this::runRead, this.getClass().getSimpleName() + "_read").start();
+            new Thread(this::runWrite, this.getClass().getSimpleName() + "_write").start();
+            try {
+                mStartuplatch.await();
+                mState.set(State.RUNNING);
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            }
+        } else {
             throw new IllegalStateException("already started");
-        new Thread(this, this.getClass().getSimpleName()).start();
+        }
     }
 
     /**
-     * stop SerialInputOutputManager thread
+     * stop SerialInputOutputManager threads
      *
      * when using readTimeout == 0 (default), additionally use usbSerialPort.close() to
      * interrupt blocking read
      */
-    public synchronized void stop() {
-        if (getState() == State.RUNNING) {
+    public void stop() {
+        if(mState.compareAndSet(State.RUNNING, State.STOPPING)) {
+            synchronized (mWriteBufferLock) {
+                mWriteBufferLock.notifyAll(); // wake up write thread to check the stop condition
+            }
             Log.i(TAG, "Stop requested");
-            mState = State.STOPPING;
         }
     }
 
-    public synchronized State getState() {
-        return mState;
+    public State getState() {
+        return mState.get();
     }
 
     /**
-     * Continuously services the read and write buffers until {@link #stop()} is
-     * called, or until a driver exception is raised.
+     * @return true if the thread is still running
      */
-    @Override
-    public void run() {
-        synchronized (this) {
-            if (getState() != State.STOPPED) {
-                throw new IllegalStateException("Already running");
-            }
-            mState = State.RUNNING;
-        }
-        Log.i(TAG, "Running ...");
-        try {
-            if(mThreadPriority != Process.THREAD_PRIORITY_DEFAULT)
-                Process.setThreadPriority(mThreadPriority);
-            while (true) {
-                if (getState() != State.RUNNING) {
-                    Log.i(TAG, "Stopping mState=" + getState());
-                    break;
-                }
-                step();
-            }
-        } catch (Exception e) {
-            Log.w(TAG, "Run ending due to exception: " + e.getMessage(), e);
-            final Listener listener = getListener();
-            if (listener != null) {
-              listener.onRunError(e);
-            }
-        } finally {
-            synchronized (this) {
-                mState = State.STOPPED;
-                Log.i(TAG, "Stopped");
+    private boolean isStillRunning() {
+        State state = mState.get();
+        return ((state == State.RUNNING) || (state == State.STARTING))
+            && !Thread.currentThread().isInterrupted();
+    }
+
+    /**
+     * Notify listener of an error
+     *
+     * @param e the exception
+     */
+    private void notifyErrorListener(Throwable e) {
+        Listener listener = getListener();
+        if (listener != null) {
+            try {
+                listener.onRunError(e instanceof Exception ? (Exception) e : new Exception(e));
+            } catch (Throwable t) {
+                Log.w(TAG, "Exception in onRunError: " + t.getMessage(), t);
             }
         }
     }
 
-    private void step() throws IOException {
+    /**
+     * Set the thread priority
+     */
+    private void setThreadPriority() {
+        if (mThreadPriority != Process.THREAD_PRIORITY_DEFAULT) {
+            Process.setThreadPriority(mThreadPriority);
+        }
+    }
+
+    /**
+     * Continuously services the read buffers until {@link #stop()} is called, or until a driver exception is
+     * raised.
+     */
+    void runRead() {
+        Log.i(TAG, "runRead running ...");
+        try {
+            setThreadPriority();
+            mStartuplatch.countDown();
+            do {
+                stepRead();
+            } while (isStillRunning());
+            Log.i(TAG, "runRead: Stopping mState=" + getState());
+        } catch (Throwable e) {
+            if (Thread.currentThread().isInterrupted()) {
+                Log.w(TAG, "runRead: interrupted");
+            } else if(mSerialPort.isOpen()) {
+                Log.w(TAG, "runRead ending due to exception: " + e.getMessage(), e);
+            } else {
+                Log.i(TAG, "runRead: Socket closed");
+            }
+            notifyErrorListener(e);
+        } finally {
+            if (mState.compareAndSet(State.RUNNING, State.STOPPING)) {
+                synchronized (mWriteBufferLock) {
+                    mWriteBufferLock.notifyAll(); // wake up write thread to check the stop condition
+                }
+            } else if (mState.compareAndSet(State.STOPPING, State.STOPPED)) {
+                Log.i(TAG, "runRead: Stopped mState=" + getState());
+            }
+        }
+    }
+
+    /**
+     * Continuously services the write buffers until {@link #stop()} is called, or until a driver exception is
+     * raised.
+     */
+    void runWrite() {
+        Log.i(TAG, "runWrite running ...");
+        try {
+            setThreadPriority();
+            mStartuplatch.countDown();
+            do {
+                stepWrite();
+            } while (isStillRunning());
+            Log.i(TAG, "runWrite: Stopping mState=" + getState());
+        } catch (Throwable e) {
+            if (Thread.currentThread().isInterrupted()) {
+                Log.w(TAG, "runWrite: interrupted");
+            } else if(mSerialPort.isOpen()) {
+                Log.w(TAG, "runWrite ending due to exception: " + e.getMessage(), e);
+            } else {
+                Log.i(TAG, "runWrite: Socket closed");
+            }
+            notifyErrorListener(e);
+        } finally {
+            if (!mState.compareAndSet(State.RUNNING, State.STOPPING)) {
+                if (mState.compareAndSet(State.STOPPING, State.STOPPED)) {
+                    Log.i(TAG, "runWrite: Stopped mState=" + getState());
+                }
+            }
+        }
+    }
+
+    private void stepRead() throws IOException {
         // Handle incoming data.
         byte[] buffer;
         synchronized (mReadBufferLock) {
@@ -234,21 +309,26 @@ public class SerialInputOutputManager implements Runnable {
                 listener.onNewData(data);
             }
         }
+    }
 
+    private void stepWrite() throws IOException, InterruptedException {
         // Handle outgoing data.
-        buffer = null;
+        byte[] buffer = null;
         synchronized (mWriteBufferLock) {
-            len = mWriteBuffer.position();
+            int len = mWriteBuffer.position();
             if (len > 0) {
                 buffer = new byte[len];
                 mWriteBuffer.rewind();
                 mWriteBuffer.get(buffer, 0, len);
                 mWriteBuffer.clear();
+                mWriteBufferLock.notifyAll(); // Notify writeAsync that there is space in the buffer
+            } else {
+                mWriteBufferLock.wait();
             }
         }
         if (buffer != null) {
             if (DEBUG) {
-                Log.d(TAG, "Writing data len=" + len);
+                Log.d(TAG, "Writing data len=" + buffer.length);
             }
             mSerialPort.write(buffer, mWriteTimeout);
         }

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/util/UsbUtils.java

@@ -0,0 +1,33 @@
+package com.hoho.android.usbserial.util;
+
+import android.hardware.usb.UsbDeviceConnection;
+
+import java.util.ArrayList;
+
+public class UsbUtils {
+
+    private UsbUtils() {
+    }
+
+    public static  ArrayList<byte[]> getDescriptors(UsbDeviceConnection connection) {
+        ArrayList<byte[]> descriptors = new ArrayList<>();
+        byte[] rawDescriptors = connection.getRawDescriptors();
+        if (rawDescriptors != null) {
+            int pos = 0;
+            while (pos < rawDescriptors.length) {
+                int len = rawDescriptors[pos] & 0xFF;
+                if (len == 0)
+                    break;
+                if (pos + len > rawDescriptors.length)
+                    len = rawDescriptors.length - pos;
+                byte[] descriptor = new byte[len];
+                System.arraycopy(rawDescriptors, pos, descriptor, 0, len);
+                descriptors.add(descriptor);
+                pos += len;
+            }
+        }
+        return descriptors;
+    }
+
+
+}

usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/util/XonXoffFilter.java

@@ -0,0 +1,47 @@
+package com.hoho.android.usbserial.util;
+
+import com.hoho.android.usbserial.driver.UsbSerialPort;
+
+import java.io.IOException;
+
+/**
+ * Some devices return XON and XOFF characters inline in read() data.
+ * Other devices return XON / XOFF condition thru getXOFF() method.
+ */
+
+public class XonXoffFilter {
+    private boolean xon = true;
+
+    public XonXoffFilter() {
+    }
+
+    public boolean getXON()  {
+        return xon;
+    }
+
+    /**
+     * Filter XON/XOFF from read() data and remember
+     *
+     * @param data unfiltered data
+     * @return filtered data
+     */
+    public byte[] filter(byte[] data) {
+        int found = 0;
+        for (int i=0; i<data.length; i++) {
+            if (data[i] == UsbSerialPort.CHAR_XON || data[i] == UsbSerialPort.CHAR_XOFF)
+                found++;
+        }
+        if(found == 0)
+            return data;
+        byte[] filtered = new byte[data.length - found];
+        for (int i=0, j=0; i<data.length; i++) {
+            if (data[i] == UsbSerialPort.CHAR_XON)
+                xon = true;
+            else if(data[i] == UsbSerialPort.CHAR_XOFF)
+                xon = false;
+            else
+                filtered[j++] = data[i];
+        }
+        return filtered;
+    }
+}

usbSerialForAndroid/src/test/java/android/util/Log.java

@@ -17,6 +17,11 @@ public class Log {
         return 0;
     }
 
+    public static int w(String tag, String msg, Throwable tr) {
+        System.out.println("WARN: " + tag + ": " + msg + " / " + tr.getMessage());
+        return 0;
+    }
+
     public static int e(String tag, String msg) {
         System.out.println("ERROR: " + tag + ": " + msg);
         return 0;

usbSerialForAndroid/src/test/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriverTest.java

@@ -1,9 +1,13 @@
 package com.hoho.android.usbserial.driver;
 
+import static com.hoho.android.usbserial.driver.CdcAcmSerialDriver.USB_SUBCLASS_ACM;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThrows;
+import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.hardware.usb.UsbConstants;
@@ -12,6 +16,8 @@ import android.hardware.usb.UsbDeviceConnection;
 import android.hardware.usb.UsbEndpoint;
 import android.hardware.usb.UsbInterface;
 
+import com.hoho.android.usbserial.util.HexDump;
+
 import org.junit.Test;
 
 import java.io.IOException;
@@ -28,14 +34,37 @@ public class CdcAcmSerialDriverTest {
         UsbEndpoint readEndpoint = mock(UsbEndpoint.class);
         UsbEndpoint writeEndpoint = mock(UsbEndpoint.class);
 
+        /*
+         * digispark - no IAD
+         *   UsbInterface[mId=0,mAlternateSetting=0,mName=null,mClass=2,mSubclass=2,mProtocol=1,mEndpoints=[
+         *     UsbEndpoint[mAddress=131,mAttributes=3,mMaxPacketSize=8,mInterval=255]]
+         *   UsbInterface[mId=1,mAlternateSetting=0,mName=null,mClass=10,mSubclass=0,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=1,mAttributes=2,mMaxPacketSize=8,mInterval=0]
+         *     UsbEndpoint[mAddress=129,mAttributes=2,mMaxPacketSize=8,mInterval=0]]
+         */
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray(
+                "12 01 10 01 02 00 00 08 D0 16 7E 08 00 01 01 02 00 01\n" +
+                "09 02 43 00 02 01 00 80 32\n" +
+                "09 04 00 00 01 02 02 01 00\n" +
+                "05 24 00 10 01\n" +
+                "04 24 02 02\n" +
+                "05 24 06 00 01\n" +
+                "05 24 01 03 01\n" +
+                "07 05 83 03 08 00 FF\n" +
+                "09 04 01 00 02 0A 00 00 00\n" +
+                "07 05 01 02 08 00 00\n" +
+                "07 05 81 02 08 00 00"));
         when(usbDeviceConnection.claimInterface(controlInterface,true)).thenReturn(true);
         when(usbDeviceConnection.claimInterface(dataInterface,true)).thenReturn(true);
         when(usbDevice.getInterfaceCount()).thenReturn(2);
         when(usbDevice.getInterface(0)).thenReturn(controlInterface);
         when(usbDevice.getInterface(1)).thenReturn(dataInterface);
+        when(controlInterface.getId()).thenReturn(0);
         when(controlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(controlInterface.getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
         when(controlInterface.getEndpointCount()).thenReturn(1);
         when(controlInterface.getEndpoint(0)).thenReturn(controlEndpoint);
+        when(dataInterface.getId()).thenReturn(1);
         when(dataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
         when(dataInterface.getEndpointCount()).thenReturn(2);
         when(dataInterface.getEndpoint(0)).thenReturn(writeEndpoint);
@@ -96,7 +125,7 @@ public class CdcAcmSerialDriverTest {
 
     @Test
     public void multiPortDevice() throws Exception {
-        int n = 4;
+        int n = 2;
         UsbDeviceConnection usbDeviceConnection = mock(UsbDeviceConnection.class);
         UsbDevice usbDevice = mock(UsbDevice.class);
         UsbInterface[] controlInterfaces = new UsbInterface[n];
@@ -105,6 +134,42 @@ public class CdcAcmSerialDriverTest {
         UsbEndpoint[] readEndpoints = new UsbEndpoint[n];
         UsbEndpoint[] writeEndpoints = new UsbEndpoint[n];
 
+        /*
+         * pi zero - dual port
+         *   UsbInterface[mId=0,mAlternateSetting=0,mName=TinyUSB CDC,mClass=2,mSubclass=2,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=129,mAttributes=3,mMaxPacketSize=8,mInterval=16]]
+         *   UsbInterface[mId=1,mAlternateSetting=0,mName=null,mClass=10,mSubclass=0,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=2,mAttributes=2,mMaxPacketSize=64,mInterval=0]
+         *     UsbEndpoint[mAddress=130,mAttributes=2,mMaxPacketSize=64,mInterval=0]]
+         *   UsbInterface[mId=2,mAlternateSetting=0,mName=TinyUSB CDC,mClass=2,mSubclass=2,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=131,mAttributes=3,mMaxPacketSize=8,mInterval=16]]
+         *   UsbInterface[mId=3,mAlternateSetting=0,mName=null,mClass=10,mSubclass=0,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=4,mAttributes=2,mMaxPacketSize=64,mInterval=0]
+         *      UsbEndpoint[mAddress=132,mAttributes=2,mMaxPacketSize=64,mInterval=0]]
+         */
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray(
+                "12 01 00 02 EF 02 01 40 FE CA 02 40 00 01 01 02 03 01\n" +
+                "09 02 8D 00 04 01 00 80 32\n" +
+                "08 0B 00 02 02 02 00 00\n" +
+                "09 04 00 00 01 02 02 00 04\n" +
+                "05 24 00 20 01\n" +
+                "05 24 01 00 01\n" +
+                "04 24 02 02\n" +
+                "05 24 06 00 01\n" +
+                "07 05 81 03 08 00 10\n" +
+                "09 04 01 00 02 0A 00 00 00\n" +
+                "07 05 02 02 40 00 00\n" +
+                "07 05 82 02 40 00 00\n" +
+                "08 0B 02 02 02 02 00 00\n" +
+                "09 04 02 00 01 02 02 00 04\n" +
+                "05 24 00 20 01\n" +
+                "05 24 01 00 03\n" +
+                "04 24 02 02\n" +
+                "05 24 06 02 03\n" +
+                "07 05 83 03 08 00 10\n" +
+                "09 04 03 00 02 0A 00 00 00\n" +
+                "07 05 04 02 40 00 00\n" +
+                "07 05 84 02 40 00 00\n"));
         when(usbDevice.getInterfaceCount()).thenReturn(2*n);
         for(int i=0; i<n; i++) {
             controlInterfaces[i] = mock(UsbInterface.class);
@@ -114,11 +179,14 @@ public class CdcAcmSerialDriverTest {
             writeEndpoints[i] = mock(UsbEndpoint.class);
             when(usbDeviceConnection.claimInterface(controlInterfaces[i], true)).thenReturn(true);
             when(usbDeviceConnection.claimInterface(dataInterfaces[i], true)).thenReturn(true);
-            when(usbDevice.getInterface(2*i+0)).thenReturn(controlInterfaces[i]);
+            when(usbDevice.getInterface(2*i  )).thenReturn(controlInterfaces[i]);
             when(usbDevice.getInterface(2*i+1)).thenReturn(dataInterfaces[i]);
+            when(controlInterfaces[i].getId()).thenReturn(2*i);
             when(controlInterfaces[i].getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+            when(controlInterfaces[i].getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
             when(controlInterfaces[i].getEndpointCount()).thenReturn(1);
             when(controlInterfaces[i].getEndpoint(0)).thenReturn(controlEndpoints[i]);
+            when(dataInterfaces[i].getId()).thenReturn(2*i+1);
             when(dataInterfaces[i].getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
             when(dataInterfaces[i].getEndpointCount()).thenReturn(2);
             when(dataInterfaces[i].getEndpoint(0)).thenReturn(writeEndpoints[i]);
@@ -130,18 +198,39 @@ public class CdcAcmSerialDriverTest {
             when(writeEndpoints[i].getDirection()).thenReturn(UsbConstants.USB_DIR_OUT);
             when(writeEndpoints[i].getType()).thenReturn(UsbConstants.USB_ENDPOINT_XFER_BULK);
         }
-        int i = 2;
+        int i = 1;
         CdcAcmSerialDriver driver = new CdcAcmSerialDriver(usbDevice);
         CdcAcmSerialDriver.CdcAcmSerialPort port = (CdcAcmSerialDriver.CdcAcmSerialPort) driver.getPorts().get(i);
         port.mConnection = usbDeviceConnection;
+        // reset invocations from countPorts()
+        clearInvocations(controlInterfaces[0]);
+        clearInvocations(controlInterfaces[1]);
+
         port.openInt();
         assertEquals(readEndpoints[i], port.mReadEndpoint);
         assertEquals(writeEndpoints[i], port.mWriteEndpoint);
+        verify(controlInterfaces[0], times(0)).getInterfaceClass(); // not openInterface with 'no IAD fallback'
+        verify(controlInterfaces[1], times(2)).getInterfaceClass(); // openInterface with IAD
+        port.closeInt();
+        clearInvocations(controlInterfaces[0]);
+        clearInvocations(controlInterfaces[1]);
+
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(null);
+        port.openInt();
+        verify(controlInterfaces[0], times(2)).getInterfaceClass(); // openInterface with 'no IAD fallback'
+        verify(controlInterfaces[1], times(2)).getInterfaceClass(); // openInterface with 'no IAD fallback'
+        port.closeInt();
+        clearInvocations(controlInterfaces[0]);
+        clearInvocations(controlInterfaces[1]);
+
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray("01 02 02 82 02")); // truncated descriptor
+        port.openInt();
+        verify(controlInterfaces[0], times(2)).getInterfaceClass(); // openInterface with 'no IAD fallback'
+        verify(controlInterfaces[1], times(2)).getInterfaceClass(); // openInterface with 'no IAD fallback'
     }
 
     @Test
     public void compositeDevice() throws Exception {
-        // mock BBC micro:bit
         UsbDeviceConnection usbDeviceConnection = mock(UsbDeviceConnection.class);
         UsbDevice usbDevice = mock(UsbDevice.class);
         UsbInterface massStorageInterface = mock(UsbInterface.class);
@@ -153,6 +242,42 @@ public class CdcAcmSerialDriverTest {
         UsbEndpoint readEndpoint = mock(UsbEndpoint.class);
         UsbEndpoint writeEndpoint = mock(UsbEndpoint.class);
 
+        /*
+         * BBC micro:bit
+         *   UsbInterface[mId=0,mAlternateSetting=0,mName=USB_MSC,mClass=8,mSubclass=6,mProtocol=80,mEndpoints=[
+         *     UsbEndpoint[mAddress=130,mAttributes=2,mMaxPacketSize=64,mInterval=0]
+         *     UsbEndpoint[mAddress=2,mAttributes=2,mMaxPacketSize=64,mInterval=0]]
+         *   UsbInterface[mId=1,mAlternateSetting=0,mName=mbed Serial Port,mClass=2,mSubclass=2,mProtocol=1,mEndpoints=[
+         *     UsbEndpoint[mAddress=131,mAttributes=3,mMaxPacketSize=16,mInterval=32]]
+         *   UsbInterface[mId=2,mAlternateSetting=0,mName=mbed Serial Port,mClass=10,mSubclass=0,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=4,mAttributes=2,mMaxPacketSize=64,mInterval=0]
+         *     UsbEndpoint[mAddress=132,mAttributes=2,mMaxPacketSize=64,mInterval=0]]
+         *   UsbInterface[mId=3,mAlternateSetting=0,mName=CMSIS-DAP,mClass=3,mSubclass=0,mProtocol=0,mEndpoints=[
+         *     UsbEndpoint[mAddress=129,mAttributes=3,mMaxPacketSize=64,mInterval=1]
+         *     UsbEndpoint[mAddress=1,mAttributes=3,mMaxPacketSize=64,mInterval=1]]
+         *   UsbInterface[mId=4,mAlternateSetting=0,mName=WebUSB: CMSIS-DAP,mClass=255,mSubclass=3,mProtocol=0,mEndpoints=[]
+         */
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray(
+                "12 01 10 02 EF 02 01 40 28 0D 04 02 00 10 01 02 03 01\n" +
+                "09 02 8B 00 05 01 00 80 FA\n" +
+                "09 04 00 00 02 08 06 50 08\n" +
+                "07 05 82 02 40 00 00\n" +
+                "07 05 02 02 40 00 00\n" +
+                "08 0B 01 02 02 02 01 04\n" +
+                "09 04 01 00 01 02 02 01 04\n" +
+                "05 24 00 10 01\n" +
+                "05 24 01 03 02\n" +
+                "04 24 02 06\n" +
+                "05 24 06 01 02\n" +
+                "07 05 83 03 10 00 20\n" +
+                "09 04 02 00 02 0A 00 00 05\n" +
+                "07 05 04 02 40 00 00\n" +
+                "07 05 84 02 40 00 00\n" +
+                "09 04 03 00 02 03 00 00 06\n" +
+                "09 21 00 01 00 01 22 21 00\n" +
+                "07 05 81 03 40 00 01\n" +
+                "07 05 01 03 40 00 01\n" +
+                "09 04 04 00 00 FF 03 00 07"));
         when(usbDeviceConnection.claimInterface(controlInterface,true)).thenReturn(true);
         when(usbDeviceConnection.claimInterface(dataInterface,true)).thenReturn(true);
         when(usbDevice.getInterfaceCount()).thenReturn(5);
@@ -161,10 +286,16 @@ public class CdcAcmSerialDriverTest {
         when(usbDevice.getInterface(2)).thenReturn(dataInterface);
         when(usbDevice.getInterface(3)).thenReturn(hidInterface);
         when(usbDevice.getInterface(4)).thenReturn(vendorInterface);
+        when(massStorageInterface.getId()).thenReturn(0);
         when(massStorageInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_MASS_STORAGE);
+        when(controlInterface.getId()).thenReturn(1);
         when(controlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(controlInterface.getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
+        when(dataInterface.getId()).thenReturn(2);
         when(dataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+        when(hidInterface.getId()).thenReturn(3);
         when(hidInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_HID);
+        when(vendorInterface.getId()).thenReturn(4);
         when(vendorInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_VENDOR_SPEC);
 
         when(controlInterface.getEndpointCount()).thenReturn(1);
@@ -185,33 +316,145 @@ public class CdcAcmSerialDriverTest {
         port.openInt();
         assertEquals(readEndpoint, port.mReadEndpoint);
         assertEquals(writeEndpoint, port.mWriteEndpoint);
+
+        ProbeTable probeTable = UsbSerialProber.getDefaultProbeTable();
+        Class<? extends UsbSerialDriver> probeDriver = probeTable.findDriver(usbDevice);
+        assertEquals(driver.getClass(), probeDriver);
+    }
+
+    @Test
+    public void compositeRndisDevice() throws Exception {
+        UsbDeviceConnection usbDeviceConnection = mock(UsbDeviceConnection.class);
+        UsbDevice usbDevice = mock(UsbDevice.class);
+        UsbInterface rndisControlInterface = mock(UsbInterface.class);
+        UsbInterface rndisDataInterface = mock(UsbInterface.class);
+        UsbInterface controlInterface = mock(UsbInterface.class);
+        UsbInterface dataInterface = mock(UsbInterface.class);
+        UsbEndpoint controlEndpoint = mock(UsbEndpoint.class);
+        UsbEndpoint readEndpoint = mock(UsbEndpoint.class);
+        UsbEndpoint writeEndpoint = mock(UsbEndpoint.class);
+
+        // has multiple USB_CLASS_CDC_DATA interfaces => get correct with IAD
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray(
+                "12 01 00 02 EF 02 01 40 FE CA 02 40 00 01 01 02 03 01\n" +
+                "09 02 8D 00 04 01 00 80 32\n" +
+                "08 0B 00 02 E0 01 03 00\n" +
+                "09 04 00 00 01 E0 01 03 04\n" +
+                "05 24 00 10 01\n" +
+                "05 24 01 00 01\n" +
+                "04 24 02 00\n" +
+                "05 24 06 00 01\n" +
+                "07 05 81 03 08 00 01\n" +
+                "09 04 01 00 02 0A 00 00 00\n" +
+                "07 05 82 02 40 00 00\n" +
+                "07 05 02 02 40 00 00\n" +
+                "08 0B 02 02 02 02 00 00\n" +
+                "09 04 02 00 01 02 02 00 04\n" +
+                "05 24 00 20 01\n" +
+                "05 24 01 00 03\n" +
+                "04 24 02 02\n" +
+                "05 24 06 02 03\n" +
+                "07 05 83 03 08 00 10\n" +
+                "09 04 03 00 02 0A 00 00 00\n" +
+                "07 05 04 02 40 00 00\n" +
+                "07 05 84 02 40 00 00"));
+        when(usbDeviceConnection.claimInterface(controlInterface,true)).thenReturn(true);
+        when(usbDeviceConnection.claimInterface(dataInterface,true)).thenReturn(true);
+        when(usbDevice.getInterfaceCount()).thenReturn(4);
+        when(usbDevice.getInterface(0)).thenReturn(rndisControlInterface);
+        when(usbDevice.getInterface(1)).thenReturn(rndisDataInterface);
+        when(usbDevice.getInterface(2)).thenReturn(controlInterface);
+        when(usbDevice.getInterface(3)).thenReturn(dataInterface);
+        when(rndisControlInterface.getId()).thenReturn(0);
+        when(rndisControlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_WIRELESS_CONTROLLER);
+        when(rndisControlInterface.getInterfaceSubclass()).thenReturn(1);
+        when(rndisControlInterface.getInterfaceProtocol()).thenReturn(3);
+        when(rndisDataInterface.getId()).thenReturn(1);
+        when(rndisDataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+        when(controlInterface.getId()).thenReturn(2);
+        when(controlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(controlInterface.getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
+        when(dataInterface.getId()).thenReturn(3);
+        when(dataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+
+        when(controlInterface.getEndpointCount()).thenReturn(1);
+        when(controlInterface.getEndpoint(0)).thenReturn(controlEndpoint);
+        when(dataInterface.getEndpointCount()).thenReturn(2);
+        when(dataInterface.getEndpoint(0)).thenReturn(writeEndpoint);
+        when(dataInterface.getEndpoint(1)).thenReturn(readEndpoint);
+        when(controlEndpoint.getDirection()).thenReturn(UsbConstants.USB_DIR_IN);
+        when(controlEndpoint.getType()).thenReturn(UsbConstants.USB_ENDPOINT_XFER_INT);
+        when(readEndpoint.getDirection()).thenReturn(UsbConstants.USB_DIR_IN);
+        when(readEndpoint.getType()).thenReturn(UsbConstants.USB_ENDPOINT_XFER_BULK);
+        when(writeEndpoint.getDirection()).thenReturn(UsbConstants.USB_DIR_OUT);
+        when(writeEndpoint.getType()).thenReturn(UsbConstants.USB_ENDPOINT_XFER_BULK);
+
+        CdcAcmSerialDriver driver = new CdcAcmSerialDriver(usbDevice);
+        CdcAcmSerialDriver.CdcAcmSerialPort port = (CdcAcmSerialDriver.CdcAcmSerialPort) driver.getPorts().get(0);
+        port.mConnection = usbDeviceConnection;
+        port.openInt();
+        assertEquals(readEndpoint, port.mReadEndpoint);
+        assertEquals(writeEndpoint, port.mWriteEndpoint);
     }
 
-
     @Test
-    public void compositeRndisDevice() throws Exception {
+    public void compositeAlternateSettingDevice() throws Exception {
         UsbDeviceConnection usbDeviceConnection = mock(UsbDeviceConnection.class);
         UsbDevice usbDevice = mock(UsbDevice.class);
-        UsbInterface rndisControlInterface = mock(UsbInterface.class);
-        UsbInterface rndisDataInterface = mock(UsbInterface.class);
+        UsbInterface ethernetControlInterface = mock(UsbInterface.class);
+        UsbInterface ethernetDummyInterface = mock(UsbInterface.class);
+        UsbInterface ethernetDataInterface = mock(UsbInterface.class);
         UsbInterface controlInterface = mock(UsbInterface.class);
         UsbInterface dataInterface = mock(UsbInterface.class);
         UsbEndpoint controlEndpoint = mock(UsbEndpoint.class);
         UsbEndpoint readEndpoint = mock(UsbEndpoint.class);
         UsbEndpoint writeEndpoint = mock(UsbEndpoint.class);
 
+        // has multiple USB_CLASS_CDC_DATA interfaces => get correct with IAD
+        when(usbDeviceConnection.getRawDescriptors()).thenReturn(HexDump.hexStringToByteArray(
+                "12 01 00 02 EF 02 01 40 FE CA 02 40 00 01 01 02 03 01\n" +
+                "09 02 9A 00 04 01 00 80 32\n" +
+                "08 0B 00 02 02 06 00 00\n" +
+                "09 04 00 00 01 02 06 00 04\n" +
+                "05 24 00 20 01\n" +
+                "05 24 06 00 01\n" +
+                "0D 24 0F 04 00 00 00 00 DC 05 00 00 00\n" +
+                "07 05 81 03 08 00 01\n" +
+                "09 04 01 00 00 0A 00 00 00\n" +
+                "09 04 01 01 02 0A 00 00 00\n" +
+                "07 05 82 02 40 00 00\n" +
+                "07 05 02 02 40 00 00\n" +
+                "08 0B 02 02 02 02 00 00\n" +
+                "09 04 02 00 01 02 02 00 04\n" +
+                "05 24 00 20 01\n" +
+                "05 24 01 00 03\n" +
+                "04 24 02 02\n" +
+                "05 24 06 02 03\n" +
+                "07 05 83 03 08 00 10\n" +
+                "09 04 03 00 02 0A 00 00 00\n" +
+                "07 05 04 02 40 00 00\n" +
+                "07 05 84 02 40 00 00"));
         when(usbDeviceConnection.claimInterface(controlInterface,true)).thenReturn(true);
         when(usbDeviceConnection.claimInterface(dataInterface,true)).thenReturn(true);
-        when(usbDevice.getInterfaceCount()).thenReturn(4);
-        when(usbDevice.getInterface(0)).thenReturn(rndisControlInterface);
-        when(usbDevice.getInterface(1)).thenReturn(rndisDataInterface);
-        when(usbDevice.getInterface(2)).thenReturn(controlInterface);
-        when(usbDevice.getInterface(3)).thenReturn(dataInterface);
-        when(rndisControlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_WIRELESS_CONTROLLER);
-        when(rndisControlInterface.getInterfaceSubclass()).thenReturn(1);
-        when(rndisControlInterface.getInterfaceProtocol()).thenReturn(3);
-        when(rndisDataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+        when(usbDevice.getInterfaceCount()).thenReturn(5);
+        when(usbDevice.getInterface(0)).thenReturn(ethernetControlInterface);
+        when(usbDevice.getInterface(1)).thenReturn(ethernetDummyInterface);
+        when(usbDevice.getInterface(2)).thenReturn(ethernetDataInterface);
+        when(usbDevice.getInterface(3)).thenReturn(controlInterface);
+        when(usbDevice.getInterface(4)).thenReturn(dataInterface);
+        when(ethernetControlInterface.getId()).thenReturn(0);
+        when(ethernetControlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(ethernetControlInterface.getInterfaceSubclass()).thenReturn(6);
+        when(ethernetDummyInterface.getId()).thenReturn(1);
+        when(ethernetDummyInterface.getAlternateSetting()).thenReturn(0);
+        when(ethernetDummyInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+        when(ethernetDataInterface.getId()).thenReturn(1);
+        when(ethernetDataInterface.getAlternateSetting()).thenReturn(1);
+        when(ethernetDataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
+        when(controlInterface.getId()).thenReturn(2);
         when(controlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(controlInterface.getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
+        when(dataInterface.getId()).thenReturn(3);
         when(dataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
 
         when(controlInterface.getEndpointCount()).thenReturn(1);
@@ -250,6 +493,7 @@ public class CdcAcmSerialDriverTest {
         when(usbDevice.getInterface(0)).thenReturn(controlInterface);
         when(usbDevice.getInterface(1)).thenReturn(dataInterface);
         when(controlInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_COMM);
+        when(controlInterface.getInterfaceSubclass()).thenReturn(USB_SUBCLASS_ACM);
         when(controlInterface.getEndpointCount()).thenReturn(1);
         when(controlInterface.getEndpoint(0)).thenReturn(controlEndpoint);
         when(dataInterface.getInterfaceClass()).thenReturn(UsbConstants.USB_CLASS_CDC_DATA);
@@ -266,7 +510,7 @@ public class CdcAcmSerialDriverTest {
         CdcAcmSerialDriver driver = new CdcAcmSerialDriver(usbDevice);
         CdcAcmSerialDriver.CdcAcmSerialPort port = (CdcAcmSerialDriver.CdcAcmSerialPort) driver.getPorts().get(0);
         port.mConnection = usbDeviceConnection;
-        assertThrows(IOException.class, () ->port.openInt());
+        assertThrows(IOException.class, port::openInt);
     }
 
     @Test

usbSerialForAndroid/src/test/java/com/hoho/android/usbserial/util/HexDumpText.java

@@ -0,0 +1,44 @@
+package com.hoho.android.usbserial.util;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
+
+import org.junit.Test;
+
+import java.security.InvalidParameterException;
+
+public class HexDumpText {
+
+    @Test
+    public void toByteArray() throws Exception {
+        assertThat(HexDump.toByteArray((byte)0x4a), equalTo(new byte[]{ 0x4A}));
+        assertThat(HexDump.toByteArray((short)0x4a5b), equalTo(new byte[]{ 0x4A, 0x5B}));
+        assertThat(HexDump.toByteArray((int)0x4a5b6c7d), equalTo(new byte[]{ 0x4A, 0x5B, 0x6C, 0x7D}));
+    }
+
+    @Test
+    public void toHexString() throws Exception {
+        assertEquals("4A", HexDump.toHexString((byte)0x4a));
+        assertEquals("4A 5B", HexDump.toHexString((short)0x4a5b));
+        assertEquals("4A 5B 6C 7D", HexDump.toHexString((int)0x4a5b6c7d));
+        assertEquals("4A 5B 6C 7D", HexDump.toHexString(new byte[]{ 0x4A, 0x5B, 0x6C, 0x7D}));
+        assertEquals("5B 6C", HexDump.toHexString(new byte[]{ 0x4A, 0x5B, 0x6C, 0x7D}, 1, 2));
+    }
+
+    @Test
+    public void dumpHexString() throws Exception {
+        assertEquals("10 31 32 33 34 35 36 37 .1234567\n18 39                   .9", HexDump.dumpHexString(new byte[]{ 0x10, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x18, 0x39}));
+        assertEquals("31 32                   12", HexDump.dumpHexString(new byte[]{ 0x30, 0x31, 0x32, 0x33}, 1, 2));
+    }
+
+    @Test
+    public void toByte() throws Exception {
+        assertThat(HexDump.hexStringToByteArray("4a 5B-6c\n7d"), equalTo(new byte[]{ 0x4A, 0x5B, 0x6C, 0x7D}));
+        assertThrows(InvalidParameterException.class, () -> HexDump.hexStringToByteArray("3 "));
+        assertThrows(InvalidParameterException.class, () -> HexDump.hexStringToByteArray("3z"));
+        assertThrows(InvalidParameterException.class, () -> HexDump.hexStringToByteArray("3Z"));
+    }
+
+}

usbSerialForAndroid/src/test/java/com/hoho/android/usbserial/util/SerialInputOutputManagerTest.java

@@ -0,0 +1,55 @@
+package com.hoho.android.usbserial.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import android.hardware.usb.UsbEndpoint;
+import android.os.Process;
+
+import com.hoho.android.usbserial.driver.CommonUsbSerialPort;
+
+import org.junit.Test;
+
+public class SerialInputOutputManagerTest {
+
+
+    // catch all Throwables in onNewData() and onRunError()
+    @Test
+    public void throwable() throws Exception {
+
+        class ExceptionListener implements SerialInputOutputManager.Listener {
+            public Exception e;
+            @Override public void onNewData(byte[] data) { throw new RuntimeException("exception1"); }
+            @Override public void onRunError(Exception e) { this.e = e; throw new RuntimeException("exception2"); }
+        }
+        class ErrorListener implements SerialInputOutputManager.Listener {
+            public Exception e;
+            @Override public void onNewData(byte[] data) { throw new UnknownError("error1"); }
+            @Override public void onRunError(Exception e) { this.e = e; throw new UnknownError("error2");}
+        }
+
+        UsbEndpoint readEndpoint = mock(UsbEndpoint.class);
+        when(readEndpoint.getMaxPacketSize()).thenReturn(16);
+        CommonUsbSerialPort port = mock(CommonUsbSerialPort.class);
+        when(port.getReadEndpoint()).thenReturn(readEndpoint);
+        when(port.read(new byte[16], 0)).thenReturn(1);
+        when(port.isOpen()).thenReturn(true);
+        SerialInputOutputManager manager = new SerialInputOutputManager(port);
+        manager.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
+
+        ExceptionListener exceptionListener = new ExceptionListener();
+        manager.setListener(exceptionListener);
+        manager.runRead();
+        assertEquals(RuntimeException.class, exceptionListener.e.getClass());
+        assertEquals("exception1", exceptionListener.e.getMessage());
+
+        ErrorListener errorListener = new ErrorListener();
+        manager.setListener(errorListener);
+        manager.runRead();
+        assertEquals(Exception.class, errorListener.e.getClass());
+        assertEquals("java.lang.UnknownError: error1", errorListener.e.getMessage());
+        assertEquals(UnknownError.class, errorListener.e.getCause().getClass());
+        assertEquals("error1", errorListener.e.getCause().getMessage());
+    }
+}