xtest09_3.c

AT91sam7s 256 B/D example

/* ========================================================================== */
/*		Xtest09_3.c : Stop Watch by PIT Interrupt		      */
/* ========================================================================== */
/*			  Designed and programmed by Duck-Yong Yoon in 2007.  */

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

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
}

volatile unsigned int second, minute, hour;	// time variable
volatile unsigned int run_flag;			// stop watch run flag

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

  second++;                                     // increment 1/100 second
  if(second == 6000)                            // second = 60 ?
    { second = 0;                               // if yes, second = 0 and minute++
      minute++;
      if(minute == 60)                          // minute = 60 ?
        { minute = 0;                           // if yes, minute = 0 and hour++
          hour++;
          if(hour == 100)                       // hour = 100 ?
            hour = 0;                           // if yes, hour = 0
        }
    }

  LCD_command(0xC2);                            // display hour
  LCD_2d(hour);
  LCD_command(0xC5);                            // display minute
  LCD_2d(minute);
  LCD_command(0xC8);                            // display second
  LCD_2d(second/100);
  LCD_command(0xCB);                            // display 1/100 second
  LCD_2d(second%100);
}

void Clear_time(void)                           /* clear time */
{
  second = 0;                                   // clear time
  minute = 0;
  hour = 0;
  LCD_string(0xC0,"  00:00:00.00   ");          // clear display
}

int main(void)
{
  MCU_initialize();				// initialize AT91SAM7S256 & kit
  Delay_ms(50);					// wait for system stabilization
  LCD_initialize();				// initialize text LCD module
  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,30000-1);	// 48MHz/16/30000 = 100Hz

  AT91F_PITEnableInt(AT91C_BASE_PITC);		// initialize PIT interrupt
  AT91F_AIC_ConfigureIt(AT91C_BASE_AIC,AT91C_ID_SYS,7,1,PIT_ISR);
  AT91F_AIC_DisableIt(AT91C_BASE_AIC,AT91C_ID_SYS);

  LCD_string(0x80, "** STOP WATCH **");		// display title
  Clear_time();                                 // clear time and display
  run_flag = 0;					// default state

  while(1)
    { switch(Key_input())                       // key input
        { case 0x01 : if(run_flag == 0)		// if KEY1 & run_flag=0, strat
	                { run_flag =  1;
                          AT91F_AIC_EnableIt(AT91C_BASE_AIC,AT91C_ID_SYS);
                        }
                      else			// if KEY1 & run_flag=1, stop
                        { run_flag =  0;
                          AT91F_AIC_DisableIt(AT91C_BASE_AIC,AT91C_ID_SYS);
                        }
                      break;
          case 0x02 : if(run_flag == 1) break;	// if KEY2 & run_flag=1, ignore
                      Clear_time();		// if KEY2 & run_flag=0, clear time
                      break;
          default:    break;
        }
    }
}