hwa/atmel/avr/examples/05-1-swuart-tx/main.c

Send a '.' on TXD every 0.1s. Can use hardware UART as well as software UART.

Test application:

./main.py -b <BAUDRATE>

Note: this can fail if the system frequency is not known precisely enough (if using an internal RC oscillator for example).

config.h

 
/*  This file is part of the HWA project.
 *  Copyright (c) 2012,2015 Christophe Duparquet.
 *  All rights reserved. Read LICENSE.TXT for details.
 */
 
#ifndef CONFIG_H
#define CONFIG_H
 
#include BOARD_H
 
#include <hwa/ext/swuarta.h>
 
#define UART                    HW_SWUARTA( txd,      DIABOLO_PIN_TX,   \
                                            counter,  counter0,         \
                                            compare,  compare0,         \
                                            clkdiv,   1,                \
                                            autosync, 51,               \
                                            fastreg,  (shared,gpior0) )
 
HW_DECLARE(UART);
 
#define BPS                     115200
 
#endif

main.c

 
/*  This file is part of the HWA project.
 *  Copyright (c) 2012,2015 Christophe Duparquet.
 *  All rights reserved. Read LICENSE.TXT for details.
 */
 
#include "config.h"
 
 
int
main ( )
{
  /*  Create a HWA context to collect the hardware configuration
   *  Preload this context with RESET values
   */
  hwa( begin, reset );
 
  /*  Configure the UART
   */
  hwa( configure, UART,
       bps,       BPS,
       databits,  8,
       parity,    none,
       stopbits,  1     );
 
  /*  Write this configuration into the hardware
   */
  hwa( commit );
 
  hw( enable, interrupts );
 
  for(;;) {
 
    /*  Wait for 0.1s
     */
    hw_waste_cycles( 0.1 * HW_SYSHZ );
 
    /*  Send a '.'
     */
    while ( !hw(stat,UART).txc ) {}
    hw( write, UART, '.');
  }
}