main.c

用CODEVISION编的 AVR单片机的振荡 程序

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>

ISR(TIM0_OVF_vect) 
{
	static unsigned char pulse = 0;
	static unsigned int envelope = 0; 
	static unsigned char enval = 255;
	static unsigned char endrv = 255;
	static long temp;
	static unsigned char acosum = 0;
	static unsigned long timeout = 67500000L;
	
	if(timeout > 0) --timeout;
	
	if((pulse < 102) || (timeout == 0)) PORTB &= ~(1 << PB2);
	else PORTB |= (1 << PB2);
		
	acosum += (ACSR & (1 << ACO)) >> ACO;
	
	if(++pulse == 106) 
	{
		pulse = 0;
		if(envelope < 45) endrv = 255; 
		else if(envelope < 65) endrv = 0;
		else if(envelope < 95) endrv = 60;
		else if(envelope < 140) endrv = 40;
		else if(envelope < 335) endrv = 0;
		else if(envelope < 340) endrv = 40;
		else if(envelope < 400) endrv = 75;
		else if(envelope < 440) endrv = 90;
		else if(envelope < 480) endrv = 110;
		else if(envelope < 490) endrv = 180;
		else if(envelope < 510) endrv = 190;
		else if(envelope < 530) endrv = 200;
		else endrv = 255;
		
		temp = temp + (endrv - enval);
		
		enval = temp >> 5;
		
		if((acosum > 50) || (timeout == 0))
		{
			if(envelope < ((timeout)?272:520)) PORTB &= ~(1 << PB3);
			else PORTB |= (1 << PB3);
		}
		else PORTB |= (1 << PB3);
		acosum = 0;
				
		if(++envelope == 544) 
		{
			envelope = 0;
		}
		OCR0A = (timeout) ? enval : 255;
	}	
}

int main(void)
{
	ACSR = 0x40;
	TCCR0A = 0xc3;
	TCCR0B = 0x01;
	OCR0A = 0xff;
	DDRB = 0x0d;
	TIMSK0 = 0x02;		
	sei();
	for (;;)
	{	
		sleep_mode();
	}
	return (0);
}