xtest16_2.c

AT91sam7s 256 B/D example

/* ========================================================================== */
/*	   Xtest16_2.c : Digital Clock by DS1307 RTC(12-Hour Format)	      */
/* ========================================================================== */
/*			  Designed and programmed by Duck-Yong Yoon in 2007.  */

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

unsigned int second, minute, hour, ampm;	// time variable

void LCD_2BCD(unsigned int number)		/* display 2-digit BCD number */
{
  LCD_data((number >> 4) + '0');		// 10^1
  LCD_data((number & 0x0F) + '0');		// 10^0
}

void TWI_transmit(unsigned int address, unsigned int data) /* transmit by TWI */
{
  *AT91C_TWI_MMR = 0x00680100;			// master write, device address 1 byte
  *AT91C_TWI_IADR = address;			// device address
  *AT91C_TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_STOP|AT91C_TWI_START; // control register
  *AT91C_TWI_THR = data;			// start transmission

  while(!(*AT91C_TWI_SR & AT91C_TWI_TXCOMP));	// complete?(TXCOMP=1)
}

unsigned int TWI_receive(unsigned int address)	/* receive by TWI */
{
  *AT91C_TWI_MMR = 0x00681100;			// master read, device address 1 byte
  *AT91C_TWI_IADR = address;			// device address
  *AT91C_TWI_CR = AT91C_TWI_MSEN|AT91C_TWI_STOP|AT91C_TWI_START; // control register

  while(!(*AT91C_TWI_SR & AT91C_TWI_TXCOMP));	// complete?(TXCOMP=1)
  return *AT91C_TWI_RHR;			// read received data and return
}

int main(void)
{
  MCU_initialize();				// initialize AT91SAM7S256 & kit
  Delay_ms(50);					// wait for system stabilization
  LCD_initialize();				// initialize text LCD module

  hour = 0x12;					// initial time 12:00:00 AM
  minute = 0x00;
  second = 0x00;
  ampm = 'A';

  LCD_string(0x80," Digital Clock  ");		// display title
  LCD_string(0xC0,"  12:00:00 AM   ");
  Beep();

  AT91F_TWI_CfgPIO();				// enable TWD, TWCK pin
  AT91F_PIO_Opendrain(AT91C_BASE_PIOA,AT91C_PA4_TWCK|AT91C_PA3_TWD); // open drain
  AT91F_TWI_CfgPMC();				// enable peripheral clock for TWI

  AT91F_TWI_Configure(AT91C_BASE_TWI);		// TWI master mode
  *AT91C_TWI_CWGR = 0x00023B3B;			// about 100kHz

  TWI_transmit(0x00, second);			// innitialize DS1307 RTC
  TWI_transmit(0x01, minute);
  if(ampm == 'A')
    TWI_transmit(0x02, hour | 0x40);
  else
    TWI_transmit(0x02, hour | 0x60);
  TWI_transmit(0x03, 0x06);
  TWI_transmit(0x04, 0x01);
  TWI_transmit(0x05, 0x06);
  TWI_transmit(0x06, 0x07);
  TWI_transmit(0x07, 0x00);			// (control register = 0x00)

  while(1)
    { hour = TWI_receive(0x02) & 0x3F;		// read hour
      if(hour > 0x20)
        { hour &= 0x1F;
          ampm = 'P';
        }
      else
        ampm = 'A';

      minute = TWI_receive(0x01);		// read minute
      second = TWI_receive(0x00);		// read second

      LCD_command(0xC2); LCD_2BCD(hour);	// display hour
      LCD_command(0xC5); LCD_2BCD(minute);	// display minute
      LCD_command(0xC8); LCD_2BCD(second);	// display second
      LCD_command(0xCB); LCD_data(ampm);	// display AM/PM
    }
}