应用实例1 呼吸灯.rar

#include <AT89X52.h> #define MAX 0x50 //定时上限定义 #define MIN 0x00 //定时下限定义 #define TIMELINE 11 //时间分频常数 #define TRUE 1 #define FALSE 0 //标志位常数 unsigned int TimeCounter; bit ArrowFlg = 0; //方向标志位 unsigned char upCounter,downCounter; //增加计数器和减少计数器 sbit LED=P2^0; //T0的中断服务子函数 void T0Deal() interrupt 1 using 0 { TH0=0xf1; TL0=0xf1; TR0=1; TimeCounter++; //定时计数器增加 if(TimeCounter == TIMELINE) { if((upCounter == MAX)&&(downCounter == MIN)) //计数方向标志位切换 { ArrowFlg = FALSE; } if((upCounter == MIN)&&(downCounter == MAX)) { ArrowFlg= TRUE; } if(ArrowFlg == 1) //如果是增加计数 { upCounter++; downCounter--; } else //如果是减少计数 { upCounter--; downCounter++; } TimeCounter=0; } } //延时函数 void Delay(unsigned int i) { unsigned int j; while(i--) { for(j=0;j<32;j++); //延时 } } void main() { upCounter = MIN; downCounter = MAX; //计数器初始化 TMOD = 0x01; //设置定时器工作方式 TH0 = 0xF0; TL0 = 0xF0 ; //T0初始化值 EA = 1; ET0 = 1; //开中断 TR0 = 1; //启动T0 while(1) { LED=0; //输出变化的PWM波形 Delay(downCounter); LED=1; Delay(upCounter); } }