51 single chip microcomputer STC89C52 matrix keyboard scanning method detection

Program source code

/*-----------------------Include header file area-------------------------*/

#include  //MCU header file 

/*-----------------------Data type definition area-----------------------*/

typedef unsigned char u8; //define type unsigned char alias u8

typedef unsigned int u16; //define type unsigned int alias u16

/*-----------------------User-defined data area---------------------*/

#define FOSC 11059200L  //System clock

#define Timer_value (65536-(FOSC/12/1000)*1) //Timer value = (timer overflow value - (system clock/12T mode/1000 = timer value for timing 1ms)) * timing time in ms) 

//The common anode digital tube displays the character array, and the corresponding characters are "0123456789ABCDEF-"

code u8 LED_Table[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0xBF,0xFF};

u8 LED_show[8]; //Data array displayed by digital tube

u8 key;  //Get the key value variable

/*-----------------------Port/Pin Definition Area----------------------*/

sbit x1=P1^0; //Port connected to the first row of the matrix

sbit x2=P1^1; //Port connected to the second row of the matrix

sbit x3=P1^2; //Port connected to the third row of the matrix

sbit x4=P1^3; //Port connected to the 4th row of the matrix

sbit y1=P1^4; //Port connected to the first column of the matrix

sbit y2=P1^5; //Port connected to the second column of the matrix

sbit y3=P1^6; //Port connected to the third column of the matrix

sbit y4=P1^7; //Port connected to the 4th column of the matrix

/*-----------------------Function declaration area---------------------------*/ 

void delay(u16 ms); //delay function declaration

void Timer0_Init(void); //Timer 0 configuration function declaration

void LED_Scan(void); //Declaration of digital tube scanning function

u8 Get_KEY_value(void); //Get key value function declaration

/*-----------------------Main function area-----------------------------*/

void main()

{

Timer0_Init(); //Timer 0 initialization

while(1)  // Repeat the while loop program

{

if(Get_KEY_value()!=0) //The returned key value is not equal to 0, which means a key is pressed

{

delay(10); //delay to eliminate jitter

if(Get_KEY_value()!=0) //Confirm whether the key is actually pressed

{

key=Get_KEY_value(); //Get the key value

}

}

else //No key is pressed 

{

key=0; //If no key is pressed, key is 0

}

LED_show[0]=LED_Table[key/10]; //The first digital tube displays the tens digit of the key value

LED_show[1]=LED_Table[key%10]; //The second digital tube displays the unit digit of the key value

}

} 

/*-----------------------Timer 0 interrupt function area--------------------*/

void Timer0()interrupt 1

{

TH0=Timer_value>>8; //Reset the high 8 bits of the timer value

TL0=Timer_value; //Reset the lower 8 bits of the timer value

    LED_Scan(); //Digital tube scanning

}

/*----------------------------------------------------------------

Function name: delay()

Function: Delay

Function parameter: ms is the delay time, the delay range is 0~65535

Return value: None

----------------------------------------------------------------*/

void delay(u16 ms)

{

u8 i;

while(ms--) //loop delay 1ms times

{

for(i=115;i>0;i--); //delay 1ms

}

}

/*----------------------------------------------------------------

    Function Name: Timer0_Init()

    Function: Timer 0 initialization

    Function parameters: None

    Return value: None

----------------------------------------------------------------*/

void Timer0_Init(void)

{

TMOD=0x01; //Set timer 0 to mode 1 (16-bit counting mode)

TH0=Timer_value>>8; //Set the high 8 bits of the timer value

TL0=Timer_value; //Set the lower 8 bits of the timer value

TR0=1; //Timer 0 counter starts timing

ET0=1; //Enable timer 0 interrupt

EA=1; //Open the general interrupt

}

/*----------------------------------------------------------------

Function name: LED_Scan()

Function: Digital tube scanning

Function parameters: None

Return value: None

----------------------------------------------------------------*/

void LED_Scan(void)

{

static u8 i=0;

P0=0xFF; //Display blanking (the blanking level is opposite to the effective level. If the bit selection is enabled first and then the segment selection data is displayed, the blanking is the segment selection, otherwise the blanking is the bit selection)

P2=~(0x01< //Enable the (i+1)th digital tube position selection

P0=LED_show[i]; //Display the (i+1)th digital tube segment selection data

i=(i+1)%2; //Display 2 digital tubes

}

/*----------------------------------------------------------------

Function name: Get_KEY_value()

Function: Get key value

Function parameters: None

Return value: 0 if no key is entered, 1 to 16 if a key is entered

----------------------------------------------------------------*/

u8 Get_KEY_value(void)

{

//Detect the first row of buttons

x1=0; x2=1; x3=1; x4=1;

if(y1==0) return 1;

else if(y2==0) return 2;

else if(y3==0) return 3;

else if(y4==0) return 4;

//Detect the second row of buttons

x1=1; x2=0; x3=1; x4=1;

if(y1==0) return 5;

else if(y2==0) return 6;

else if(y3==0) return 7;

else if(y4==0) return 8;

//Detect the third row of buttons

x1=1; x2=1; x3=0; x4=1;

if(y1==0) return 9;

else if(y2==0) return 10;

else if(y3==0) return 11;

else if(y4==0) return 12;

//Detect the fourth row of buttons

x1=1; x2=1; x3=1; x4=0;

if(y1==0) return 13;

else if(y2==0) return 14;

else if(y3==0) return 15;

else if(y4==0) return 16;

return 0; //No key pressed returns 0

}

Simulation Circuit