main._c

一个关于AVR单片机的例程

// ICC-AVR application builder : 2007-5-29 15:21:23
// Target : M16
// Crystal: 7.3728Mhz
// 用途：演示定时器的计数功能
// 作者：古欣 AVR 与虚拟仪器 www.avrvi.com
// 连接：接好电源和晶振的跳线
//       7断数码管的ABCD接VCC，a~dp接PA0～PA7
//       PB0接一个独立按键

#include <iom16v.h>
#include <macros.h>

const unsigned char seg7_data[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x00};//0~F and "shut"


void port_init(void)
{
 PORTA = 0xFF;
 DDRA  = 0xFF;
 PORTB = 0x01; //PB0，是TIMER0的外部时钟输入脚（T0），需要设为输入，并且使能内部上拉
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

//TIMER0 initialize - prescale:Falling edge
// WGM: Normal
// desired value: 1KHz
// actual value: Out of range
void timer0_init(void)
{
 TCCR0 = 0x00; //stop
 TCNT0 = 0x00; //set count
 OCR0  = 0x0A;  //set compare十进制的十，十次按键后匹配，进入这里
 TCCR0 = 0x06; //start timer 时钟由T0 引脚输入，下降沿触发
}

#pragma interrupt_handler timer0_comp_isr:20
void timer0_comp_isr(void)
{
 //compare occured TCNT0=OCR0
 //按下键OCR0次后，会进入本中断
 TCNT0 = 0x00;
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 timer0_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x02; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void main(void)
{
 init_devices();
 while(1)
 {
  PORTA = seg7_data[TCNT0]; //一直显示TCNT0的值
 }
}