main._c

一个用mega8开发的速度发生器,速度比较准确,值得下载

//ICC-AVR application builder : 2006-10-11 上午 11:30:40
// Target : M8
// Crystal: 6.0000Mhz

#include <iom8v.h>
#include <macros.h>

 unsigned char flag =0;

void port_init(void)
{
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

//Watchdog initialize
// prescale: 16K 
void watchdog_init(void)
{
 WDR(); //this prevents a timout on enabling
 WDTCR = 0x08; //WATCHDOG ENABLED - dont forget to issue WDRs
}

//TIMER1 initialize - prescale:1
// WGM: 0) Normal, TOP=0xFFFF
// desired value: 320Hz
// actual value: 320.000Hz (0.0%)
void timer1_init(void)
{
 TCCR1B = 0x00; //stop
 TCNT1H = 0xB6; //setup
 TCNT1L = 0xC2;
 OCR1AH = 0x49;
 OCR1AL = 0x3E;
 OCR1BH = 0x49;
 OCR1BL = 0x3E;
 ICR1H  = 0x49;
 ICR1L  = 0x3E;
 TCCR1A = 0x00;
 TCCR1B = 0x01; //start Timer
}

#pragma interrupt_handler timer1_ovf_isr:9
void timer1_ovf_isr(void)
{
 //TIMER1 has overflowed
 TCNT1H = 0xB6; //reload counter high value
 TCNT1L = 0xC2; //reload counter low value
 
 
  if(flag ==0)
  {
      PORTD |= 0x04;
	  flag =1;
  }else
  {
      PORTD &= ~(0x04);
	  flag =0;
  }
 
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 watchdog_init();
 timer1_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x04; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

//************************************************************ 
 void main(void)
 {
  init_devices();
  DDRD  |= 0x04;
  PORTD |= 0x04;
  flag =1;
  
  while(1)
  {
   WDR();
  }

 }
//************************************************************