main.c

基于AVRGCC的时钟DS1302的完整应用源代码

/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <[e-mail]> wrote this file. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return. Joerg Wunsch
* ----------------------------------------------------------------------------
*
* Simple AVR demonstration. Controls a LED that can be directly
* connected from OC1/OC1A to GND. The brightness of the LED is
* controlled with the PWM. After each period of the PWM, the PWM
* value is either incremented or decremented, that’s all.
*
* $Id: simple-demo.c,v 1.3 2002/02/11 19:51:51 j Exp $
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include <sig-avr.h>
#if defined(__AVR_AT90S2313__)
# define OC1 PB3
# define OCR OCR1L
# define DDROC DDRB
#elif defined(__AVR_AT90S2333__) || defined(__AVR_AT90S4433__)
# define OC1 PB1
# define DDROC DDRB
# define OCR OCR1L
#elif defined(__AVR_AT90S4414__) || defined(__AVR_AT90S8515__) || \
defined(__AVR_AT90S4434__) || defined(__AVR_AT90S8535__) || \
defined(__AVR_ATmega163__)
# define OC1 PD5
# define DDROC DDRD
# define OCR OCR1AL
#else
# error "Don’t know what kind of MCU you are compiling for"
#endif

volatile uint16_t pwm;
volatile enum
{
	UP, DOWN
} direction;

SIGNAL(SIG_OVERFLOW1)
{
	switch (direction)
	{
		case UP:
			if (++pwm == 1023) direction = DOWN;
			break;
		case DOWN:
			if (--pwm == 0) direction = UP;
			break;
	}
	outw(OCR, pwm);
}

void ioinit(void)
{
	#if defined(COM11)
	outp(BV(PWM10)|BV(PWM11)|BV(COM11), TCCR1A); /* tmr1 is 10-bit PWM */
	#elif defined(COM1A1)
	outp(BV(PWM10)|BV(PWM11)|BV(COM1A1), TCCR1A); /* tmr1 is 10-bit PWM */
	#else
	# error "need either COM1A1 or COM11"
	#endif
	outp(BV(CS10), TCCR1B); /* tmr1 running on full MCU clock */
	outw(OCR, 0); /* set PWM value to 0 */
	outp(BV(OC1), DDROC); /* enable OC1 and PB2 as output */
	timer_enable_int(BV(TOIE1));
	sei(); /* enable interrupts */
}

int main(void)
{
	ioinit();
	for (;;)
	/* wait forever, the interrupts are doing the rest */;
	return 0;
}