8、定时器扫描按键实验

2019-04-15 14:40发布

站内文章 / PIC单片机
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#include "reg52.h" //定义51单片机特殊功能寄存器 #include "absacc.h" bit key_re; unsigned char key_press; unsigned char key_value; bit key_flag; unsigned char intr; // 0 1 2 3 4 5 6 7 8 9 code unsigned char tab[] = { 0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90, 0xff}; unsigned char dspbuf[8] = {10,10,10,10,10,0,0,0}; //显示缓冲区 unsigned char dspcom = 0; unsigned char read_key(void); void display(void); //主函数 void main(void) { unsigned char key_temp; unsigned char num; P3 = 0xff; //按键接口初始化 TMOD |= 0x01; //配置定时器工作模式 TH0 = (65536-2000)/256; TL0 = (65536-2000)%256; EA = 1; ET0 = 1; //打开定时器中断 TR0 = 1; //启动定时器 while(1) { if(key_flag) { key_flag = 0; key_temp = read_key(); } //进入按键处理程序部分 switch(key_temp) { case 1: num++; break; case 2: num--; break; } key_temp = 0; //完成按键处理程序后，清除键值 dspbuf[5] = num/100; dspbuf[6] = num%100/10; dspbuf[7] = num%10; } } //定时器中断服务函数 void isr_timer_0(void) interrupt 1 //默认中断优先级 1 { TH0 = (65536-2000)/256; TL0 = (65536-2000)%256; //定时器重载 display(); if(++intr == 10) //2ms执行一次 { intr = 0; key_flag = 1; //20ms按键扫描标志位置1 } } //读取键值 unsigned char read_key(void) { unsigned char key_temp; key_temp = (P3&0x0f); if(key_temp != 0x0f) //有按键按下 key_press++; else key_press = 0; //抖动 if(key_press == 5) { key_press = 0; key_re = 1; switch(key_temp) { case 0x0e: key_value = 1; // break; case 0x0d: key_value = 2; // break; case 0x0b: key_value = 3; // break; case 0x07: key_value = 4; // break; } } //连续三次检测到按键被按下，并且该按键已经释放 if((key_re == 1) && (key_temp == 0x0f)) { key_re = 0; return key_value; } return 0xff; //无按键按下或被按下的按键未被释放 } //显示函数 void display(void) { XBYTE[0xE000] = 0xff; //消隐 XBYTE[0xC000] = (1<

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