timer.c

单片机应用 1.1602LCD 2.2004LCD源码 3.ATmega16 PWM源码 4.ATmega8 LED源码 5.无线影音Nrf2401源码 6.AVR串口源码

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

#define Uchar 	unsigned char
#define Uint 	unsigned int
#define Ulong 	unsigned long

Uchar 	time_init;
Uchar 	CNT1;
Uchar 	CNT2;
Uchar	CNT3;
Uchar 	LMT1;
Uchar 	LMT2;
Uchar	LMT3;

//TIMER1 initialize - prescale:1024
// WGM: 0) Normal, TOP=0xFFFF
// desired value: 1Hz
// actual value:  1.000Hz (0.0%)
void timer1_init(void)
{
	TCCR1B = 0x00; //stop
 	TCNT1H = 0xfe; //setup
 	TCNT1L = 0x00;
 	OCR1AH = 0x0F;
 	OCR1AL = 0x42;
 	OCR1BH = 0x0F;
 	OCR1BL = 0x42;
 	ICR1H  = 0x0F;
 	ICR1L  = 0x42;
 	TCCR1A = 0x00;
 	TCCR1B = 0x01; //start Timer
}

#pragma interrupt_handler timer1_ovf_isr:9
void timer1_ovf_isr(void)
{
 	TCNT1H = 0xfe; //reload counter high value
 	TCNT1L = 0x00; //reload counter low value
    ++CNT1;
	if(CNT1>=LMT1)
	{
		CNT1=0;
		if(++CNT2>=LMT2)
		{
			CNT2=0;
			CNT3=~CNT3;
		}
	}
	time_init=1;    
}

/*void flush(UCHAR ios,UCHAR ioc)
{
	UCHAR a;
	if(time_init)
	{
		time_init=0;
		if(CNT1<=CNT2)
		{
			PORTB=ios;
		}
		else
		PORTB=ioc;
	}
}
*/
void main(void)
{     
	OSCCAL=0X9d;
	CLI(); //disable all interrupts
 	timer1_init();
 	PORTB = 0x00;
 	DDRB = 0xff;
 	MCUCR = 0x00;
 	GICR  = 0x00;
 	TIMSK = 0x04; //timer interrupt sources
 	time_init=0;
    LMT1=250;
    LMT2=250;
    LMT3=1;
    CNT1=CNT2=CNT3=0;
    SEI(); //re-enable interrupts

	while(1)
	{
		if (!CNT3)
		{
			if(time_init)
			{
				time_init=0;
				if(CNT1<=CNT2)
				{
					PORTB=1;
				}
				else
				PORTB=0;
			}
		}
		else
		if(time_init)
		{
			time_init=0;
			if(CNT1<=CNT2)
			{
				PORTB=0;
			}
			else
			PORTB=1;
		}
	}
}