keypwm.c

温度控制PWM

/**********************************************************
*Header:
*File Name:
*Author: 陈培炜，杨帆
*Data;2007
*Function:
*********************************************************/
#include <REG52.h>
#include "DS18B20.h"
#include "Lcd.h"


sbit pwmout = P1^0;
sbit led1 = P1^1;
sbit led2 = P1^2;
sbit led3 = P1^3;
sbit led4 = P1^4;
sbit led5 = P1^5;
sbit led6 = P1^6;
sbit led7 = P1^7;
unsigned char code alltime = 10000;
unsigned int tempreture = 0;  //存放温度数值
unsigned int High = 5000;	 //存放高电平延时时间
unsigned int Low = 5000;	//存放低电平延时时间

extern unsigned char ut;   //外部设置的上限温度
extern unsigned char dt;   //外部设置的下限温度

/**********************************************************
*Header:
*File Name:
*Author: 陈培炜，杨帆
*Data;2007
*Function:	   用延时做PWM
*********************************************************/

void DelayPwm(unsigned int t)
{
	unsigned int a;
	for(a=t; a!=0; a--)
	{
		;
	}
}

/**********************************************************
*Header:
*File Name:
*Author: 陈培炜，杨帆
*Data;2007	   
*Function:	 PWM高底电平输出
*********************************************************/

void Pwm(void)
{ 
   pwmout = 1;
   DelayPwm(High);
   pwmout = 0;
   DelayPwm(Low); 

}

/**********************************************************
*Header:
*File Name:
*Author: 陈培炜，杨帆
*Data;2007
*Function:	  定时器初始化
*********************************************************/

unsigned char TimerNum = 0x00;
void T0InterruptInitial(void)
{
	  
	TMOD = (TMOD & 0xf0) | 0x01;     	// 方式1,手动赋值赋值,定时长度65536 //	
	TH0 = TimerNum;	// 定时0.001ms    	
	TL0 = TimerNum;

}	

/*************************************************
/*Header:DS18B20.h
/*File Name:main.c 
/*Author: 陈培炜，杨帆
/*Data;2007
/*Function:	   定时器中断程序
/************************************************/
void T0interrupt(void) interrupt 1
{
	TH0 = TimerNum;	// 定时0.001ms    	
	TL0 = TimerNum;
	tempreture = read0(); 	   //在定时中断一到就读一次温度

	if( tempreture>=30 && tempreture<=50 )    //如果读到的温度在30-50之间则计算高底电平延时时间
	{
		High = 25000-500*tempreture;		//占空比(50-t)/20
        Low = alltime - High;
	}
	else
	{
		High = 5000;
		Low = 5000;
	}

	if(tempreture<=dt)     //判断温度是否小于设定温度的下限值,如果小于,则LED亮
	{
	    led1 = 0;
		led2 = 0;
		led3 = 0;
	    led4 = 0;
		led5 = 0;
		led6 = 0;
		led7 = 0;
	}
	if(tempreture>=ut)	   //判断温度是否大于设定温度的上限值,如果大于,则LED灭
	{
	    led1 = 1;
		led2 = 1;
		led3 = 1;
	    led4 = 1;
		led5 = 1;
		led6 = 1;
		led7 = 1;
	} 
	disp(tempreture,High); //显示温度值和占空比
}