xtest14_7.c

AT91sam7s 256 B/D example

/* ========================================================================== */
/*		Xtest14_7.c : USART0 Loopback Test by RS-232C Cable	      */
/* ========================================================================== */
/*			  Designed and programmed by Duck-Yong Yoon in 2007.  */

#include "AT91SAM7S256.h"
#include "lib_AT91SAM7S256.h"
#include "OK7S256ads.h"

void USART0_TX_char(unsigned int data)		/* transmit a character by USART0 */
{
  while(!(*AT91C_US0_CSR & 0x0002));		// wait until TXRDY=1

  *AT91C_US0_THR = data;			// transmit a character
}

unsigned int USART0_RX_char(void)		/* receive a character by USART0 */
{
  unsigned int i;

  i = 0;
  while(!(*AT91C_US0_CSR & 0x0001) && (i < 1000000)) // wait until RXRDY=1
    i++;

  if(i < 1000000)
    return *AT91C_US0_RHR;			// receive a character
  else
    return ' ';
}

int main(void)
{
  unsigned int i, RxD;

  MCU_initialize();				// initialize AT91SAM7S256 & kit
  Delay_ms(50);					// wait for system stabilization
  LCD_initialize();				// initialize text LCD

  LCD_string(0x80,"USART0 Loopback2");		// display title

  AT91F_US0_CfgPMC();				// enable clock of USART0
  AT91F_PIO_CfgPeriph(AT91C_BASE_PIOA,AT91C_PA6_TXD0|AT91C_PA5_RXD0,0);
						// TXD0, RXD0 by Peripheral A

  *AT91C_US0_MR = 0x100008C0;			// normal mode, no parity
						// 8 data, 1 stop, LSB first, 16x
  *AT91C_US0_BRGR = 26;				// MCK/16/26 = 115200 bps
  *AT91C_US0_CR = 0x00000150;			// TX, RX enable

  while(1)
    { for(i = 'A'; i <= 'Z'; i++)
        { LCD_string(0xC0,"TxD=0,RxD=0     ");
          USART0_TX_char(i);			// transmit a character
	  LCD_command(0xC4); LCD_data(i);	// display TxD

          RxD = USART0_RX_char();		// receive a character
	  LCD_command(0xCA); LCD_data(RxD);	// display RxD

          if(RxD == i)				// if equal, OK
            { LCD_string(0xCB, ", OK!");
              Beep();
            }
          else					// if not equal, error
            { LCD_string(0xCB, ",Err!");
              Error();
            }

          Delay_ms(2000);
        }
    }
}