Identification of PIC16F877 Matrix Keyboard

The identification method of the matrix keyboard has been discussed in the 51 matrix keyboard identification. Now let's talk about the difference between the PIC microcontroller and the 51 microcontroller. The main difference is that the input and output of the PIC microcontroller port requires the TRISn register setting, as follows:

 

 

Scanning method:

#include
#define uchar unsigned char
#define uint unsigned int
uchar num;
const uchar SSEG[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c ,0x39,0x5e,0x79,0x71};

void delay1ms(uint z)
{
 uint x;
 uchar y;
 for(x=z;x>0;x--)
  for(y=110;y>0;y--);
}

void keyscan()
{
 uchar temp;
 TRISB=0x0f;
 PORTB=0x7f;
 temp=PORTB&0x0f;
 if(temp!=0x0f)
 {
  delay1ms(10);
  temp=PORTB&0x0f;
  if(temp!=0x0f)
  {
   num=temp|0x70 ; 
  }
  temp=PORTB&0x0f;
  while(temp!=0x0f)
  {
   temp=PORTB&0x0f;   
  }
  switch(num)
  {
   case 0x7e: num =12;break;
    case 0x7d: num =13;break;
   case 0x7b: num =14;break ;
   case 0x77: num =15;break;
  }
 }
 PORTB=0xbf;
 temp=PORTB&0x0f;
 if(temp!=0x0f)
 {
  delay1ms(10);
  temp=PORTB&0x0f;
  if(temp!=0x0f)
  {
   num=temp|0xb0; 
  }
  temp=PORTB&0x0f;
  while(temp!=0x0f)
  {
   temp=PORTB&0x0f;   
  }
  switch(num)
  {
   case 0xbe: num =8;break;
    case 0xbd: num =9;break;
   case 0xbb: num =10;break;
   case 0xb7: num =11;break;
  }
 }
 PORTB=0xdf;
 temp=PORTB&0x0f;
 if(temp!=0x0f)
 {
  delay1ms(10);
  temp=PORTB&0x0f;
  if(temp!=0x0f)
  {
   num=temp|0xd0; 
  }
  temp=PORTB&0x0f;
  while(temp!=0x0f)
  {
   temp=PORTB&0x0f;   
  }
  switch(num)
  {
   case 0xde: num =4;break;
    case 0xdd: num =5;break;
   case 0xdb: num =6;break;
   case 0xd7: num =7;break;
  }
 }
 PORTB=0xef;
 temp=PORTB&0x0f;
 if(temp!=0x0f)
 {
  delay1ms(10);
  temp =PORTB&0x0f;
  if(temp!=0x0f)
  {
   num=temp|0xe0; 
  }
  temp=PORTB&0x0f;
  while(temp!=0x0f)
  {
   temp=PORTB&0x0f;   
  }
  switch(num)
  {
   case 0xee: num =0;break;
    case 0xed: num =1;break;
   case 0xeb: num =2;break;
   case 0xe7: num =3;break;
  }
 }       
}

void main()
{
 num=0xff;
 TRISD=0;
 PORTD=0;
 while(1)
 {
  keyscan();
  PORTD=~SSEG[num];
 }
}

 

Line reversal method:

#include
#define uchar unsigned char
#define uint unsigned int
uchar num;
const uchar SSEG[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c ,0x39,0x5e,0x79,0x71};

void delay1ms(uint z)
{
 uint x;
 uchar y;
 for(x=z;x>0;x--)
  for(y=110;y>0;y--);
}

void keyscan()
{
 uchar temp,z,x;
 TRISB=0x0f;
 PORTB=0x0f;
 x=PORTB&0x0f;
 if(x!=0x0f)
 {
  delay1ms(10);
  x=PORTB&0x0f;
  if(x!=0x0f)
  {
   temp =PORTB&0x0f;
   TRISB=0xf0 ; PORTB
   =  0xf0;  z  
   = temp | PORTB
   ; break; case 0xde: num =4; break; case 0xbe: num =8; break; case 0x7e: num =12; break; case 0xed: num =1; break; case 0xdd: num =5; break; case 0xbd: num =9; break; case 0x7d: num =13; break; case 0xeb: num =2; break; case 0xdb: num =6; break;  case 0xbb: num =10;break; case 0x7b: num =14;break ; case 0xe7: num =3;break; case 0xd7: num =7;break; case 0xb7: num =11;break; case 0x77: num =15;break; } } } }
   
   
     
   
   
   
    
         
         
         
         
         
         
         
         
            
         
         
         
         
         
         
   
  
 

void main()
{
 num=0xff;
 TRISD=0;
 PORTD=0;
 while(1)
 {
  keyscan();
  PORTD=~SSEG[num];
 }
}