hwa/atmel/avr/examples/05-2-swuart-sync-rx-tx/main.c

Reply to incoming 'A' with software UART registers dtn & dt0.

Test application:

./main.py

config.h

#ifndef CONFIG_H
#define CONFIG_H
 
#include BOARD_H
 
#include <hwa/ext/swuarta.h>
 
#define UART                    HW_SWUARTA( txd,      DIABOLO_PIN_TX,   \
                                            rxd,      DIABOLO_PIN_RX,   \
                                            startirq, (DIABOLO_PIN_RX,port,pcic,irq), \
                                            counter,  counter1,         \
                                            compare,  compare0,         \
                                            clkdiv,   1,                \
                                            autosync, 51,               \
                                            fastreg,  (shared,gpior0) )
 
HW_DECLARE(UART);
 
#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"
 
 
void uart_putbyte ( uint8_t byte )
{
  while ( !hw(stat,UART).txc )
    hw( wait, irq );
  hw( write, UART, byte );
}
 
 
int
main ( )
{
  /*  Create a HWA context to collect the hardware configuration
   *  Preload this context with RESET values
   */
  hwa( begin, reset );
 
  /*  Configure the software UART
   */
  hwa( configure, UART );
  hwa( enable, (DIABOLO_PIN_RX,port,pcic,irq) );
  hwa( turn, (DIABOLO_PIN_RX,port,pcic), DIABOLO_PIN_RX, on );
 
  /*  Configure the LED pin
   */
  hwa( configure, PIN_LED, mode, digital_output );
 
  /*  Have the CPU enter idle mode when the 'sleep' instruction is executed.
   */
  hwa( configure,  core0,
       sleep,      enabled,
       sleep_mode, idle     );
 
  /*  We can change the system clock frequency if we do not use
   *  a crystal oscillator.
   */
#if !defined HW_DEVICE_CLK_SRC_HZ
  hwa( write, (core0, osccal), 0xFF );
#endif
 
  /*  Write this configuration into the hardware
   */
  hwa( commit );
 
  /*  Interrupt requests must be serviced for swuart
   */
  hw( enable, interrupts );
 
 
  /*  Main loop:
   *    synchronize UART
   *    process incomming commands until error
   */
  for(;;) {
 
    /*  Signal UART desynchronization
     */
    hw( write, PIN_LED, 0 );
 
    /*  Force UART to re-synchronize
     */
    hw( reset, UART );
 
    /*  Wait for UART synchronization, then send the prompt
     */
    while ( !hw(stat,UART).sync )
      hw( wait, irq );
 
    hw( write, UART, '$');
 
    /*  Signal UART synchronization
     */
    hw( write, PIN_LED, 1 );
 
    /*  Process commands
     */
    for(;;) {
 
      /*  Wait for a command
       */
      while ( !hw(stat,UART).rxc )
        hw( wait, irq );
 
      uint8_t byte = hw( read, UART );
 
      /*  Process it
       */
      if ( byte=='A' ) {
        hw( write, PIN_LED, 1 );
        /*
         *  Known command: reply with values of UART registers dtn, dt0
         */
        uint16_t dt ;
 
        dt = hw( read, (UART,dtn) ) ;
        uart_putbyte( (dt>>0) & 0xFF );
        uart_putbyte( (dt>>8) & 0xFF );
 
        dt = hw( read, (UART,dt0) ) ;
        uart_putbyte( (dt>>0) & 0xFF );
        uart_putbyte( (dt>>8) & 0xFF );
 
        uart_putbyte( '$' );
 
        hw( write, PIN_LED, 0 );
      }
      else {
        /*
         *  Unknown command: -> resync
         */
        break ;
      }
    }
  }
}