display.c

avr单片机atmega8系列led显示测试程序

//ICC-AVR application builder : 2005-2-24 23:07:53
// Target : M8
// Crystal: 8.0000Mhz

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

unsigned char  n;

//TIMER1 initialisation - prescale:256
// actual value:  1.000Hz (0.0%)
void timer1_init(void)
{
 TCCR1B = 0x00; //stop
 TCNT1H = 0x85; //setup
 TCNT1L = 0xEE;
 OCR1AH = 0x7A;
 OCR1AL = 0x12;
 OCR1BH = 0x7A;
 OCR1BL = 0x12;
 ICR1H  = 0x7A;
 ICR1L  = 0x12;
 TCCR1A = 0x00;
 TCCR1B = 0x04; //start Timer
}

//  timer1 中断 ，1秒
#pragma interrupt_handler timer1_ovf_isr:9
void timer1_ovf_isr(void)
{
    unsigned char  ch,i;

    TCNT1H = 0x85; //reload counter high value
    TCNT1L = 0xEE; //reload counter low value

    if(++n == 10) n = 0;
    ch = n | 0x70;
    PORTB &= ~0x01;      //  消隐
    PORTD &= ~0x40;      //  CLK
    for(i=0; i<8; i++){
        if(ch & 0x80)
            PORTD |= 0x80;
        else
            PORTD &= ~0x80;
        ch <<= 1;
        PORTD |= 0x40;
        asm("nop");
        PORTD &= ~0x40;
    }
    PORTB |= 0x01;      //  显示
}

//  初始化
void init_devices(void)
{
 CLI();          //  禁止中断
 DDRB = 0x01;    //  初始化操作74LS164的管脚
 DDRD = 0xC0;    //  初始化操作74LS164的管脚
 timer1_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x04;   //  设置timer1中断
 SEI();          //  中断使能
}

//
void main(void)
{
 unsigned char   x;
 init_devices();
 //insert your functional code here...
 for(;;){
   x++;
 }
}