PS/2 Barcode Scanner with PIC18F2220

// define the clock and data bits
#define AT_CLK PORTCbits.RC14					// clock on RC14
#define AT_CLK_ENABLE  TRISCbits.TRISC14
#define AT_DATA PORTCbits.RC13					// data on RC13
#define AT_DATA_ENABLE  TRISCbits.TRISC13

// initialise the AT keyboard clock and data bits for input
void ATkbdInitialise(void)
{
   AT_CLK_ENABLE=1;				// enable keyboard CLK input
   AT_DATA_ENABLE=1;			// enable keyboard DATA input 
}

// decode the CLK and DATA lines into an integer - polled version
static int ATkbdRead(int debug)
{
    int i=0, scanCode=0;;
    char data[20]={0};
	while(AT_DATA);				// wait for start bit - high to low transition
    while(AT_CLK);				// wait for clock high to low transition
	//printf("START BIT");
    // read 8 bits of data + parity + stop bit
    for(i=0; i< 10; i++)
      {
       while(!AT_CLK);				// wait for clock low to high
       while(AT_CLK);				// wait for clock high to low
	   data[i]=AT_DATA+'0';			// read the next data bit
      }
    if(debug)printf("%s ", data);
    // convert the pattern into an 8 bit scan code
    for(i=7; i>=0; i--)
      {
       scanCode=(scanCode<<1) | (data[i]-'0');
      }
    if(debug)printf("scan code %x ", scanCode);
    return scanCode;
}