基礎：

1. 點亮二極體的壓降為 1.6–1.7V，工作電流為3–10 mA；低電平點亮

2.線與指的是它們任意一開關只要對地導通，這根線就一定是低電平。

3.微控制器I/O預設輸入高電平；

LED 燈點亮

電路圖：

# include<reg52.h>
int main()
{
     P1=0xb3;   //10110011   匯流排點亮
    return 0;
}

# include<reg52.h>
sbit led0=P1^0;  
sbit led1=P1^2;     //用來宣告P1.1口為程式所要控制的埠,"sbit"
 
是KEIL專門用來宣告某位IO口
int main()
{
    //P1=0xb3;  //10110011
    led0=0;
    led1=0;
    return 0;
}

獨立按鍵掃描

電路圖：

# include<reg52.h>
sbit led0=P1^0;
sbit key3=P3^5;
int main()
{
    P3=0xff;         // 將P3 I/O口設定為輸入狀態。但按下鍵盤時，對應的I/O口為低電平
    while(1){
       if(key3==0)      // 當key3按下時，點亮led0 。
           led0=0;
        else
 

           led0=1;
    }
    return 0;
}

數碼管動態顯示

電路圖： P2口的低四位進行片選，P0口進行段選

#include <reg52.h>
#define uchar unsigned char
#define uint  unsigned int
uchar table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};        //共陰極的段選
uchar table1[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80
 
,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};        //共陰極的段選
uchar DuanXuan[]={0xfe,0xfc,0xfb,0xf7};
uchar st;
void delay(uint x){
    while(x--);
}
int main()
{
     while(1){
        for(st=0;st<4;st++){
           P2=DuanXuan[st];
           P0=table1[st];
           delay(100);
        }
    }
        return 0;
}

#include <reg52.h>
#define uchar unsigned char
#define uint  unsigned int

uchar table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};        //共陰極的段選
uchar table1[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};        //共陰極的段選
uchar We[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf};
uchar st;
sbit WE=P2^7;
sbit DU=P2^6;
void delay(uint xms){
    uint i,j;
    for(i=xms; i>0; i--)
       for(j=110; j>0; j--);
}
void main()
{
     while(1){
        for(st=0;st<6;st++){
           WE=1;
           P0=We[st];
           WE=0;
           DU=1;
           P0=table[st];
           DU=0;
           delay(500);
        } 
    } 
}