AVR Freaks

#include 
#include 
#include 

#define setbit(port,bit)  ((port) |=  (1<<bit)) // set bit
#define clrbit(port,bit)  ((port) &= ~(1<<bit)) // clear bit

#define ROW1 PINC0 // pin1
#define ROW2 PINC1 // pin2
#define ROW3 PINC2 // pin3
#define ROW4 PINC3 // pin4

#define COL1 PD0 // pin1
#define COL2 PD1 // pin2
#define COL3 PD2 // pin3
#define COL4 PD3 // pin4

int main(void)
{
   DDRA=0xFF; // Making PORTA as output Port (DATA)
   DDRB=0x07; // Making PORTB as output (CONTROL)
   DDRD=0xFF;
   DDRC=0x00;
   PORTC |= 0x0f; // pull-up on input pins
    
   LCD_init(); // LCD Intialization
   LCD_goto(1,1); // To choose from which line and character the string has to be displayed
   LCD_print("THE PRESSED KEY:"); // String which has to be displayed on LCD

   MCUCSR=(1<<JTD); // DISABLING JTAG
   MCUCSR=(1<<JTD);

   PORTC=0x00; //MAKING PORTC AS INPUT
   PORTD=0xFF; //MAKING PORTD AS OUTPUT

   while(1)  // main loop
   {
      // FIRST COLUMN
      PORTD = PORTD & 0x0F; // set all columns to 1 
      clrbit(PORTD,COL1);   // link column 1 to GND (PORTB.0 = 0)
      asm volatile ("nop");

      while (bit_is_clear(PIND,COL1)) //CHECK IN 1sT COLOUMN
      {
         _delay_ms(50);  // debounce
         
         if (bit_is_clear(PINC,ROW1)) //CHECK IF ANY KEY IN ROW 1 IS PRESSED
         {
            LCD_goto(2,7);
            LCD_print("0");
            break;
         }

         if (bit_is_clear(PINC,ROW2)) //CHECK IF ANY KEY IN ROW 2 IS PRESSED
         {
            LCD_goto(2,7);
            LCD_print("1");
            break;
         }
         // test ROW 3,4
      
         loop_until_bit_is_set(PIND,COL1); // wait for buton released
      }
      
      // SECOND COLUMN
      PORTD = PORTD & 0x0f; // set all columns to 1 
      clrbit(PORTD,COL2);   // link column 2 to GND (PORTB.1 = 0)
      asm volatile ("nop");

      while (bit_is_clear(PIND,COL2)) //CHECK IN 2nd COLOUMN
      {
         _delay_ms(50);  // debounce
         
         if (bit_is_clear(PINC,ROW1)) //CHECK IF ANY KEY IN ROW 1 IS PRESSED
         {
         ...
         ...

   } //while(1)
} //main()