定时器.c

AVR单片机计时器操作

//ICC-AVR application builder : 2007-8-31 21:15:43
// Target : M162
// Crystal: 8.0000Mhz

#include <iom162v.h>
#include <macros.h>
const led_table[16]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x88,0x86,0xc7,0xc4,0x83,0x8b};// 0~~f
//定义LED的数据表，注意，只有0到9是正确的，A-F没有认真写。
 unsigned char i;

void port_init(void)
{
 PORTA = 0x00;
 DDRA  = 0xFF;
 PORTB = 0xFF;
 DDRB  = 0x00;
 PORTC = 0xFF; 
 DDRC  = 0x00;
 PORTD = 0xFF;
 DDRD  = 0x00;
 PORTE = 0xFF;
 DDRE  = 0x00;
}

//TIMER1 initialize - prescale:1024
// WGM: 0) Normal, TOP=0xFFFF
// desired value: 1mSec
// actual value:  0.896mSec (10.4%)
void timer1_init(void)
{
 TCCR1B= 0x00; //stop
 TCNT1H= 0xFF; //setup 
 TCNT1L= 0xF9;
 OCR1AH= 0x00;
 OCR1AL= 0x07;
 OCR1BH= 0x00;
 OCR1BL= 0x07;
 TCCR1A= 0x00;
 TCCR1B= 0x05; //start Timer 
}

#pragma interrupt_handler timer1_ovf_isr:16
void timer1_ovf_isr(void)
{
 //TIMER1 has overflowed
 TCNT1H= 0xFF; //reload counter high value
 TCNT1L= 0xF9; //reload counter low value
  i++;
 if(i==10) i=0; //等于十时，恢复零
 PORTA=led_table[i]; //这里使LED变化

}

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

 MCUCR= 0x00; 
 EMCUCR = 0x00;
 TIMSK= 0x80; //设定允许定时器1的TOIE1 7 
 ETIMSK=0x00;
 GICR= 0x00;
 PCMSK1=0x00;
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void main(void)
{
 init_devices();
 while(1)
;
 
}