Single-chip microcomputer-control button to light up the LED light

1. Button circuit diagram

Define four button pins 

1. When the button is pressed, the input is low level

2. If the button is not pressed, the IO has a pull-up resistor, which is high level

// Define the discipline of the key
sbit KEY1 = P3^1;
sbit KEY2 = P3^0;
sbit KEY3 = P3^2;
sbit KEY4 = P3^3;

2. LED lamp circuit diagram

LED output high level is bright

// Define the LED light control
sbit LED1 = P2^0;
sbit LED2 = P2^1;
sbit LED3 = P2^2;
sbit LED4 = P2^3;

3. Programming thought design

1. Define button management

2. Definition of LED light management

3. Define the key value of the button

4. Define a function to determine whether the button is pressed

5. First judge whether the button is pressed --> how about judging that the button is not pressed --> otherwise return not pressed

static u8 key =1;  // Define a variable key of u8 type that will not be changed and assign it a value of 1 
if(mode)key=1;        // Continuously scan keys, here the word scan is 0, and multiple scans are 1

if(key=1 && (KEY1==0 || KEY2==0 || KEY3==0 || KEY4==0))  // key1 ==0 is pressed, why use || or operator only If one is true, that button is pressed

#include "reg52.h"

// 重新命名类型
typedef unsigned char u8;
typedef unsigned int u16;

// 定义 按键的 管教
sbit KEY1 = P3^1;
sbit KEY2 = P3^0;
sbit KEY3 = P3^2;
sbit KEY4 = P3^3;

// 定义LED灯 管教
sbit LED1 = P2^0;
sbit LED2 = P2^1;
sbit LED3 = P2^2;
sbit LED4 = P2^3;


// 使用宏定义独立按键按下的键值
#define KEY1_PRESS 1
#define KEY2_PRESS 2
#define KEY3_PRESS 3
#define KEY4_PRESS 4
#define KEY_UNPRESS 0
// 延时函数
void delay_times(u16 times)
{
	while(times--);
}

// 按键函数
u8 key_scan(u8 mode)
{
	static u8 key =1;  // 定义一个不被改变的u8 类型的 变量 key 赋值为1 
	if(mode)key=1;	   // 连续扫描按键，这里给 是单词扫描为0 ，多次扫描为1
	if(key=1 && (KEY1==0 || KEY2==0 || KEY3==0 || KEY4==0))  // key1 ==0 为按下， 为什么用 || 或运算符 只有有一个为真，就是那个按键按下了
	{
	 	delay_times(1000);  // 消抖  1000us = 10 ms
		key =0;
		if(KEY1 == 0)
		{
			return KEY1_PRESS; 
		}
		else if(KEY2 == 0)
		{
			return KEY2_PRESS;
		}
		else if(KEY3 == 0)
		{
			return KEY3_PRESS;
		}
		else if(KEY4 == 0)
		{
			return KEY4_PRESS;
		}
	}
	else if(KEY1 ==1 && KEY2 ==1 && KEY3 == 1 && KEY4 ==1)	 // 这里是判断 按键没有被按下，为什么用 && 与运算  只要条件都为真，那就都为真
	{
		key =1;
	}
	return KEY_UNPRESS; 
}

// 主函数
void main()
{
	u8 key=0;
	while(1)
	{
		key=key_scan(1);	  // key_scan 有返回值需要被接收   
		if(key==KEY1_PRESS)
			LED1=~LED1;		  // LED1灯 取反 发光
		else if(key==KEY2_PRESS)
			LED2=~LED2;
		else if(key==KEY3_PRESS)
			LED3=~LED3;
		else if(key==KEY4_PRESS)
			LED4=~LED4;	
	}
}

4. Realize the effect