led01.c

AVR单片机ATMEGA48控制LED灯的C程序

/*-----------------------------------------------------------------------------
 * File: LED01.C
 * Author: David Boydston - Solutions Consulting - http://www.serialio.com
 * Copyright (c) 1999 Solutions Consulting All Rights Reserved.
 *
 * Function: Test the light sequence on Atmel 8515 development board
 * Lights should blink one at a time 'up' from PB0 to PB7 then back 'down'
 * from PB7 to PB0. Then the lights will 'stack up' from PB0 to PB7 and
 * 'stack down' from PB7 to PB0. At any time when the PB2 button is
 * pressed the lights should display with an alternating pattern momentarily
 * then continue with the blinking pattern.
 *
 * See disclaimer at http://www.serialio.com/Legal/SoftDisclaimer.htm
 *---------------------------------------------------------------------------*/

#include <io8515.h>
#include <macros.h>

#define CLK_DIV_BY_0		0x01 //rolls at 8.19ms with 4Mhz Clock 
#define CLK_DIV_BY_8		0x02 //rolls at 65.5ms with 4Mhz Clock 
#define CLK_DIV_BY_64		0x03 //rolls at 524ms  with 4Mhz Clock 
#define CLK_DIV_BY_256		0x04 //rolls at 2.1sec with 4Mhz Clock 
#define CLK_DIV_BY_1024		0x05 //rolls at 8.4sec with 4Mhz Clock 
#define TMR1_OVF_INT_ENA	0x80
#define GLOBAL_INT_ENA		0x80
#define INT0_ENA			0x40
#define INT0_TRIG_FALL_EDGE	0x02
#define INT1_ENA			0x80

unsigned char tmrRollFlag = 0;

void delay2(unsigned char);
#pragma interrupt_handler ISR_int0_handler:2
//Note: GIMSK I-bit cleared by MCU on INT and set by MCU on RETI
//Thus there should be no danger of us being involked multiple 
//times by switch bounce (as long as delay is reasonable to see LED)
void ISR_int0_handler()
{
	unsigned char a, b;
	PORTB = 0x55;
	delay2(5); //doing this in ISR causes heavy stack use.
/*
//this way is easier on the stack
	for (a = 1; a; a++)
		for (b = 1; b; b++)
			;
*/			
}

#pragma interrupt_handler ISR_tmr1_ovf_handler:7
void ISR_tmr1_ovf_handler()
{
//	 PORTB = 0x0f; //sanity check
	 tmrRollFlag = 1;
}

void delay(unsigned char n)
{
	int i;
	
	for (i = 0; i < n; i++) {
		tmrRollFlag = 0;
		while (!tmrRollFlag); //wait for IRQ
	}

}

#ifdef FIXED_DELAY
void delay()
{
	tmrRollFlag = 0;
	while (!tmrRollFlag); //wait for IRQ
}
#endif

void delay2(unsigned char n)
{
	unsigned char a, b, c;

	for (a = 1; a; a++)
		for (b = 1; b; b++)
			for (c = 1; c<n; c++)
			;
}

void LED_On(int i)
{
	PORTB = ~BIT(i);	/* low output to turn LED on */
//	delay2(0);
	delay(3);
}

void main()
{
	signed char i, v;

	DDRB = 0xFF;	/* output */
	PORTB = 0x55; //sanity check
	delay2(5);

	TCCR1A = 0;
	TCCR1B = CLK_DIV_BY_8;
//	TCCR1B = CLK_DIV_BY_64;
	TIMSK = TMR1_OVF_INT_ENA;
	
	MCUCR = INT0_TRIG_FALL_EDGE;
	MCUCR = 0; //low level trig
	GIMSK = INT0_ENA;
	
	SREG = GLOBAL_INT_ENA; //enable ints

	while (1)
	{
		/* forward march */
		for (i = 0; i < 8; i++)
			LED_On(i);
		/* backward march, don't repeat bit 7 */
		for (i = 6; i >= 0; i--)
			LED_On(i);
//PORTB = 0xF0; //sanity check
//delay();
		/* stack, don't repeat bit 0 */
		for (i = 0, v = 3; i < 7; i++) {
			PORTB = ~v;
			v |= v << 1;
			delay(3);
		}
		/* unstack */
		for (i = 0, v = 0x7F; i < 8; i++) {
			PORTB = ~v;
			v &= v >> 1;
			delay(3);
		}
	}
}