Keypad Interface Using C

[Shan]

Hi everyone..

I need c-program to scan the keypad ad send the result to first seriat port.

Here P1.0 to P1.3 should represent columns and

P2.0 to P 2.3 should represent rows.

This is where im stuck now.

 

# include <reg51.h> // Header for AT89C51

 

 

sbit R0=P2^0;   // Row 1 of the Keypad

sbit R1=P2^1;   // Row 2 of the Keypad

sbit R2=P2^2;   // Row 3 of the Keypad

sbit R3=P2^3;   // Row 4 of the Keypad

sbit C0=P1^0;   // Column 1 of the Keypad

sbit C1=P1^1;   // Column 2 of the Keypad

sbit C2=P1^2;   // Column 3 of the Keypad

sbit C3=P1^3;   // Column 4 of the Keypad 

 

int row_read();   // Row Read Function Declaration

 

int col_read();    // Colum Read Function Declaration

 

void delay(int);   // Dealy Function Declaration

 

void delay(int a)

{   int i;  

 for(i=0;i<a;i++);  }

 

int row_read ()// Row Read Function Define

 {           

P2=0x0F;      // Set The Higher Nibble High

  if(R0==1) 

{ return(1); } 

else if(R1==1) 

{ return(2); } 

else if(R2==1)

 { return(3); } 

else if(R3==1)

 { return(4); } 

delay(10000);  }

 int col_read ()// Column Read Function Define

 {

           P1=0x0F;    // Set The Lower Nibble High

 if(C0==1) 

{  return(1); } 

else if(C1==1) 

{ return(2); }

 else if(C2==1) 

{ return(3); }

 else if(C3==1) 

{ return(4); } 

delay(10000); 

} 

main ()  {   int j=0,i=0;  

while(1)

Now here what should i write to call the rows and cloumns scanning functions + to get output..??

 

 

[AJISH ALFRED]

Hi Shan,

Please post the circuit diagram

[Author]

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