51单片机实现呼吸灯

一、概述

使用51单片机控制LED，实现其由暗变亮，再由亮变暗的渐变过程。

二、程序

#include <STC15F2K60S2.H>

#include "MacroAndConst.h"

sbit LED = P1^5;

#define LED_ON() LED = 0; //LED亮

#define LED_OFF() LED = 1; //LED灭

#define LED_PWM_LIMIT_MAX 99

#define LED_PWM_LIMIT_MIN 0

static u8 s_u8TimeCounter = 0; //中断计数

static u8 s_u8LedDirection = 0; //LED方向控制 0：渐亮  1：渐灭

static u8 s_u8LedPWMCounter = 0; //LED占空比

void Timer0Init(void)

{

AUXR |= 0x80; //定时器时钟1T模式

TMOD &= 0xF0; //设置定时器模式

TL0 = 0x5C; //设置定时初值

TH0 = 0xF7; //设置定时初值

TF0 = 0; //清除TF0标志

TR0 = 1; //定时器0开始计时

ET0 = 1; //使能定时器0中断

}

void Timer0Isr(void) interrupt 1

{

static int8 s_u8PWMCounter = 0;

TH0 = 0xF7; //定时器初始值（200us中断1次）

TL0 = 0x5C;

if(++s_u8TimeCounter >= 100) //每20ms调整一次LED占空比

{

s_u8TimeCounter = 0;

//如果是渐亮方向变化，则占空比递增

if((s_u8LedPWMCounter <= LED_PWM_LIMIT_MAX)&&(s_u8LedDirection == 0))

{

s_u8LedPWMCounter++;

if(s_u8LedPWMCounter > LED_PWM_LIMIT_MAX)

{

s_u8LedDirection = 1;

s_u8LedPWMCounter = LED_PWM_LIMIT_MAX;

}

}

//如果是渐灭方向变化，则占空比递减

if((s_u8LedPWMCounter > LED_PWM_LIMIT_MIN)&&(s_u8LedDirection == 1))    

             //此处有坑，若写成“>=”，则达不到预期效果

{

s_u8LedPWMCounter--;

if(s_u8LedPWMCounter <= LED_PWM_LIMIT_MIN)

{

s_u8LedDirection = 0;

s_u8LedPWMCounter = LED_PWM_LIMIT_MIN;

}

}

s_u8PWMCounter = s_u8LedPWMCounter; //获取LED的占空比

}

if(s_u8PWMCounter > 0) //占空比大于0，则点亮LED，否则熄灭

{

LED_ON();

s_u8PWMCounter--;

}

else

{

LED_OFF();

}

}