MCS-51 MCU scanning matrix keyboard program

#include
#define uint unsigned int
#define uchar unsigned char

 

sbit DSCQ=P2^6; //bit defines the segment latch control terminal
sbit WSCQ=P2^7; //bit definition bit latch control terminal


uchar code table[]={0x3f,0x06,0x5b,0x4f, //0,1,2,3
     0x66,0x6d,0x7d,0x07, //4,5,6,7
     0x7f,0x6f,0x77,0x7c, //8,9,a,b
     0x39,0x5e,0x79,0x71};//c,d,e,f

void delay(uint t); //declare delay function
void keyscan(); //Declare scanning function


void main()
{
  
 DSCQ=0; //Segment latch latch
 WSCQ=0; //bit latch latch

 P0=0x00; //P0 port outputs 0000 0000
 WSCQ=1; //bit latch allows
 WSCQ=0; //Bit latch latch (the ground terminals of the digital tubes are all low level 0)

 
 P0=table[8]; //P0 port output 8
 DSCQ=1; //Segment latch allows

 while(1)
 {

   keyscan(); //constant scan
 
 }
 
}

 

void delay(uint t)
{
 uint x,y;
 for(x=t;x>0;x--)
 {
  for(y=120;y>0;y--)
  {
  

  }
  
 }

}


void keyscan()
{
 uchar key1,key2;
 P3=0xfe; //1111 1110 (set P3.0 to low level 0. Write 1 to the high 4 bits to read the status of the 4 high I/O ports)
 key1=P3; //Read P3 port for the first time
 delay(15); //delay 15ms
 key2=P3; //Read P3 port for the second time
 key1=key1&0xf0;//1111 0000 (keep the high 4 bits of the first value and mask the low 4 bits)
 key2=key2&0xf0;//1111 0000 (keep the upper 4 bits of the second value and mask the lower 4 bits)
 if((key1==key2)&&key1!=0xf0)

//If the value of key1 is equal to the value of key2, and the value of key1 is not equal to 1111 0000, it means that a key is pressed.
 {
  switch(key1)
  {
 
  case 0xe0:P0=table[0];break;//1110 0000
  case 0xd0:P0=table[1];break;//1101 0000
  case 0xb0:P0=table[2];break;//1011 0000
  case 0x70:P0=table[3];break;//0111 0000
  
  }
 
 }


 
 P3=0xfd; //1111 1101 (set P3.1 to low level 0. Write 1 to the upper 4 bits to read the status of the 4 high-bit I/O ports)
 key1=P3; //Read P3 port for the first time
 delay(15); //delay 15ms
 key2=P3; //Read P3 port for the second time
 key1=key1&0xf0; //1111 0000 retain the upper 4 bits (retain the upper 4 bits of the first value and mask the lower 4 bits)
 key2=key2&0xf0; //1111 0000 retain the upper 4 bits (retain the upper 4 bits of the second value and mask the lower 4 bits)
 if((key1==key2)&&key1!=0xf0)

//If the value of key11 is equal to the value of key2, and the value of key1 is not equal to 1111 0000, it means that a key is pressed.
 {
  switch(key1)
  {
 
  case 0xe0:P0=table[4];break;//1110 0000
  case 0xd0:P0=table[5];break;//1101 0000
  case 0xb0:P0=table[6];break;//1011 0000
  case 0x70:P0=table[7];break;//0111 0000
  
  }
 
 }

 P3=0xfb; //1111 1011 (set P3.2 to low level 0. Write 1 to the high 4 bits to read the status of the 4 high I/O ports)
 key1=P3; //Read P3 port for the first time
 delay(15); //delay 15ms
 key2=P3; //Read P3 port for the second time
 key1=key1&0xf0;//1111 0000 (keep the high 4 bits of the first value and mask the low 4 bits)
 key2=key2&0xf0;//1111 0000 (keep the upper 4 bits of the second value and mask the lower 4 bits)
 if((key1==key2)&&key1!=0xf0)

//If the value of key11 is equal to the value of key2, and the value of K1 is not equal to 1111 0000, it indicates that a key is pressed
 {
  switch(key1)
  {
 
  case 0xe0:P0=table[8];break; //1110 0000
  case 0xd0:P0=table[9];break; //1101 0000
  case 0xb0:P0=table[10];break;//1011 0000
  case 0x70:P0=table[11];break;//0111 0000
  
  }
 
 }

 

 P3=0xf7; //1111 0111 (set P3.3 to low level 0. Write 1 to the upper 4 bits to read the status of the 4 high-bit I/O ports)
 key1=P3; //Read P3 port for the first time
 delay(15); //delay 15ms
 key2=P3; //Read P3 port for the second time
 key1=key1&0xf0;//1111 0000 (keep the high 4 bits of the first value and mask the low 4 bits)
 key2=key2&0xf0;//1111 0000 (keep the upper 4 bits of the second value and mask the lower 4 bits)
 if((key1==key2)&&key1!=0xf0)

//If the value of key1 is equal to the value of key2, and the value of key1 is not equal to 1111 0000, it means that a key is pressed.
 {
  switch(key1)
  {
 
  case 0xe0:P0=table[12];break;//1110 0000
  case 0xd0:P0=table[13];break;//1101 0000
  case 0xb0:P0=table[14];break;//1011 0000
  case 0x70:P0=table[15];break;//0111 0000
  
  }
 
 }

}