c---klawiatura

#include <REGX52.H>

unsigned char key;
unsigned char key1;

void analiza (unsigned char x, unsigned char y)
  {
    if(x != y) P2 = x;
  }


void main(void)
  {
    while(1)
      {

        P0 = 0xFE; //  1111 1110
        key1 = 0xFE;
        key = P0;
        analiza(key,key1);

        P0 = 0xFD; //  1111 1101
        key1 = 0xFD;
        key = P0;
        analiza(key,key1);

        P0 = 0xFB; //  1111 1011
        key1 = 0xFB;
        key = P0;
        analiza(key,key1);

        P0 = 0xF7; //  1111 0111
        key1 = 0xF7;
        key = P0;
        analiza(key,key1);

      }
  }