Initial Commit

USART.c

@@ -0,0 +1,144 @@
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  USART.c
+
+  Description  :  Utility functions for ATmega8 USART.
+
+  Author       :  2004-10-22 - Louis Frigon
+
+  History      :  2004-10-22 - First release (v0.1).
+
+--------------------------------------------------------------------------------------------------*/
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+#include <stdio.h>
+
+#include "USART.h"
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  InitUSART
+
+  Description  :  Performs USART initialization: 9600,N,8,1.
+
+  Argument(s)  :  None.
+
+  Return value :  None.
+
+--------------------------------------------------------------------------------------------------*/
+void InitUSART ( void )
+{
+    //  Disable USART while setting baud rate.
+    UCSR0B = 0x00;
+    UCSR0A = 0x00;
+
+    //  8 data bit, 1 stop, no parity.
+    UCSR0C = _BV(EEAR7) | _BV(UCSZ01) | _BV(UCSZ00);
+
+    //  Set USART baud rate @ 9600. Divider is 103 @ 16 MHz.
+    UBRR0L = 103;
+
+    //  Enable internal pull-up on Rx pin.
+    PORTD |= _BV(PD0);
+
+    //  Enable Tx & Rx.
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0);
+}
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  UsartIsChr
+
+  Description  :  Return status of USART Rx buffer.
+
+  Argument(s)  :  None.
+
+  Return value :  0 if Rx buffer empty.
+
+--------------------------------------------------------------------------------------------------*/
+bool UsartIsChr ( void )
+{
+    return UCSR0A & _BV(RXC0);
+}
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  UsartGetChr
+
+  Description  :  Return character USART Rx buffer. Blocking until Rx buffer not empty.
+
+  Argument(s)  :  None.
+
+  Return value :  Character in Rx buffer.
+
+--------------------------------------------------------------------------------------------------*/
+char UsartGetChr ( void )
+{
+    while ( !UsartIsChr() );
+
+    return UDR0;
+}
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  UsartPutChr
+
+  Description  :  Send a character through the USART.
+
+  Argument(s)  :  c -> char to send.
+
+  Return value :  None.
+
+--------------------------------------------------------------------------------------------------*/
+void UsartPutChr ( char c )
+{
+    //  Wait for transmit register to be empty.
+    while ( !(UCSR0A & _BV(UDRE0)) );
+
+    UDR0 = c;
+}
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  UsartPutStr
+
+  Description  :  Transmit a string on the serial port.
+
+  Argument(s)  :  str -> pointer to string to send.
+
+  Return value :  None.
+
+--------------------------------------------------------------------------------------------------*/
+void UsartPutStr ( char *str )
+{
+    while ( *str )
+    {
+        UsartPutChr( *str++ );
+    }
+}
+
+/*--------------------------------------------------------------------------------------------------
+
+  Name         :  UsartPutCStr
+
+  Description  :  Transmit a string on the serial port.
+
+  Argument(s)  :  str -> pointer to constant string to send (strings in Flash).
+
+  Return value :  None.
+
+--------------------------------------------------------------------------------------------------*/
+void UsartPutCStr ( const char *str )
+{
+    char c;
+
+    while ( (c = pgm_read_byte_near( str++ )) )
+    {
+        UsartPutChr( c );
+    }
+}
+
+/*--------------------------------------------------------------------------------------------------
+                                         End of file.
+--------------------------------------------------------------------------------------------------*/