xtest10_1.c

AT91sam7s 256 B/D example

/* ========================================================================== */
/*		Xtest10_1.c : Digital Clock by PIT Interrupt		      */
/* ========================================================================== */
/*			  Designed and programmed by Duck-Yong Yoon in 2007.  */

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

volatile unsigned int PIT_count=0;		// PIT interrupt count
volatile unsigned int second, minute, hour, ampm; // time variable

void LCD_2d(unsigned int number)		/* display 2-digit decimal number */
{
  LCD_data(number/10 + '0');                    // 10^1
  LCD_data(number%10 + '0');                    // 10^0
}

void PIT_ISR(void)				/* PIT interrupt service routine */
{
  AT91F_PITGetPIVR(AT91C_BASE_PITC);		// clear PITS

  PIT_count++;					// increment PIT_count
  if(PIT_count == 4) PIT_count = 0;		// 4Hz/4 = 1Hz

  if(PIT_count != 0) return;			// display time once per second

  second++;					// increment second
  if(second == 60)                              // if second = 60, second = 0
    { second = 0;
      minute++;                                 // increment minute
      if(minute == 60)                          // if minute = 60, minute = 0
        { minute = 0;
          hour++;                               // increment hour
          if(hour == 13)                        // if hour = 13, hour = 1
            hour = 1;
          if(hour == 12)                        // if hour = 12, adjust AM/PM
            { if(ampm == 'A') ampm = 'P';
              else            ampm = 'A';
            }
        }
     }

  LCD_command(0xC2); LCD_2d(hour);		// display hour
  LCD_command(0xC5); LCD_2d(minute);		// display minute
  LCD_command(0xC8); LCD_2d(second);		// display second
  LCD_command(0xCB); LCD_data(ampm);		// display AM/PM
}

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

  hour = 12;					// initial time
  minute = 0;
  second = 0;
  ampm = 'A';

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

  AT91F_PITC_CfgPMC();				// enable peripheral clock for PIT
  AT91F_PITInit(AT91C_BASE_PITC,1,48);		// enable and initialize PIT
  AT91F_PITSetPIV(AT91C_BASE_PITC,750000-1);	// 48MHz/16/750000 = 4Hz
  
  AT91F_PITEnableInt(AT91C_BASE_PITC);		// initialize PIT interrupt
  AT91F_AIC_ConfigureIt(AT91C_BASE_AIC,AT91C_ID_SYS,7,1,PIT_ISR);
  AT91F_AIC_EnableIt(AT91C_BASE_AIC,AT91C_ID_SYS);

  while(1);					// wait for interrupt
}