CH34x flow control

the tests look like the CH34x only partially supports flow control
CTS ok: writing data correctly blocks if CTS is unset.
RTS not ok: when not reading data (fast enough), RTS is not unset on buffer full

usbSerialForAndroid/build.gradle

@@ -54,7 +54,7 @@ project.afterEvaluate {
                 // values used for local maven repo, jitpack uses github release:
                 groupId 'com.github.mik3y'
                 artifactId 'usb-serial-for-android'
-                version '3.9.1beta'
+                version '3.12.0beta'
             }
         }
     }

usbSerialForAndroid/src/androidTest/java/com/hoho/android/usbserial/DeviceTest.java

@@ -2185,6 +2185,7 @@ public class DeviceTest {
         boolean outputLineReadable = false; // getControlLines returns configured value
         FlowControl_OutputLineLocked outputLineLocked = FlowControl_OutputLineLocked.FALSE;
         boolean outputLineSet = false;
+        boolean inputFlowControl = true;
         if(usb.serialDriver instanceof ProlificSerialDriver) {
             outputLineSet = true; // line set to 'true' on setFlowControl
             outputLineLocked = FlowControl_OutputLineLocked.TRUE;  // setRts/Dtr has no effect
@@ -2197,7 +2198,9 @@ public class DeviceTest {
         if(usb.serialDriver instanceof FtdiSerialDriver) {
             outputLineLocked = FlowControl_OutputLineLocked.ON_BUFFER_FULL;
         }
-
+        if(usb.serialDriver instanceof Ch34xSerialDriver) {
+            inputFlowControl = false;
+        }
         usb.open(EnumSet.of(UsbWrapper.OpenCloseFlags.NO_CONTROL_LINE_INIT, UsbWrapper.OpenCloseFlags.NO_IOMANAGER_THREAD));
         telnet.setParameters(115200, 8, 1, UsbSerialPort.PARITY_NONE);
         usb.setParameters(115200, 8, 1, UsbSerialPort.PARITY_NONE);
@@ -2313,23 +2316,25 @@ public class DeviceTest {
             }
         }
 
-        new NoRead().run();
+        if (inputFlowControl) {
+            new NoRead().run();
 
-        // no read -> buffer full -> RTS/DTR off -> output line locked
+            // no read -> buffer full -> RTS/DTR off -> output line locked
-        if(outputLineLocked != FlowControl_OutputLineLocked.TRUE) {
+            if (outputLineLocked != FlowControl_OutputLineLocked.TRUE) {
-            assertTrue(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
-            for(i = 0; i < 120 && usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR); i++) {
-                telnet.write(buf64);
-                Thread.sleep(controlLineWait);
-            }
-            assertFalse(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
-            if(m) usb.serialPort.setRTS(true); else usb.serialPort.setDTR(true);
-            Thread.sleep(controlLineWait);
-            if(outputLineLocked == FlowControl_OutputLineLocked.ON_BUFFER_FULL)
-                assertFalse(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
-            else
                 assertTrue(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
-            data = usb.read(-1, i*64, 100);
+                for (i = 0; i < 120 && usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR); i++) {
+                    telnet.write(buf64);
+                    Thread.sleep(controlLineWait);
+                }
+                assertFalse(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR)); // RTS not unset on CH34x
+                if (m) usb.serialPort.setRTS(true); else usb.serialPort.setDTR(true);
+                Thread.sleep(controlLineWait);
+                if (outputLineLocked == FlowControl_OutputLineLocked.ON_BUFFER_FULL)
+                    assertFalse(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
+                else
+                    assertTrue(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
+                data = usb.read(-1, i * 64, 100);
+            }
         }
 
         // mode retained over close
@@ -2341,7 +2346,8 @@ public class DeviceTest {
         assertEquals(flowControl, usb.serialPort.getFlowControl());
         assertTrue(m ? usb.serialPort.getRTS() : usb.serialPort.getDTR());
         assertTrue(usb.serialPort.getControlLines().contains(m ? ControlLine.CTS : ControlLine.DSR));
-        new NoRead().run();
+        if (inputFlowControl)
+            new NoRead().run();
     }
 
     @Test

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

@@ -135,8 +135,9 @@ public class UsbWrapper implements SerialInputOutputManager.Listener {
         } else if (serialDriver instanceof Ch34xSerialDriver) {
             outputLinesSupported = true;
             inputLinesSupported = true;
-            if(serialDriver.getDevice().getProductId() == UsbId.QINHENG_CH340)
+            inputLinesConnected = true;
-                inputLinesConnected = true;  // I only have 74LS138 connected at CH340, not connected at CH341A
+            if(serialDriver.getDevice().getProductId() == UsbId.QINHENG_CH341A)
+                inputLinesOnlyRtsCts = true;
         } else if (serialDriver instanceof CdcAcmSerialDriver) {
             outputLinesSupported = true;
             inputLinesSupported = true;

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

@@ -101,6 +101,7 @@ public class Ch34xSerialDriver implements UsbSerialDriver {
 
             initialize();
             setBaudRate(DEFAULT_BAUD_RATE);
+            setFlowControl(mFlowControl);
         }
 
         @Override
@@ -357,6 +358,27 @@ public class Ch34xSerialDriver implements UsbSerialDriver {
             return EnumSet.allOf(ControlLine.class);
         }
 
+        @Override
+        public void setFlowControl(FlowControl flowControl) throws IOException {
+            if (flowControl == FlowControl.RTS_CTS) {
+                if (controlOut(0x9a, 0x2727, 0x0101) < 0) {
+                    throw new IOException("Error setting flow control");
+                }
+            } else if (flowControl == FlowControl.NONE) {
+                if (controlOut(0x9a, 0x2727, 0x0000) < 0) {
+                    throw new IOException("Error setting flow control");
+                }
+            } else {
+                throw new UnsupportedOperationException("Unsupported flow control: " + flowControl);
+            }
+            mFlowControl = flowControl;
+        }
+
+        @Override
+        public EnumSet<FlowControl> getSupportedFlowControl() {
+            return EnumSet.of(FlowControl.NONE, FlowControl.RTS_CTS);
+        }
+
         @Override
         public void setBreak(boolean value) throws IOException {
             byte[] req = new byte[2];