kb.c
/*****************************
** low level kexboard routines VERSION 1.0
******************************/
#include "kb.h"
#include "sCANcodes.h"
#define BUFF_SIZE 64
unsigned char edge, bitcount; // 0 = neg. 1 = pos.
unsigned char kb_buffer[BUFF_SIZE];
unsigned char *inpt, *outpt;
unsigned char buffcnt;
void InitKeyBoard(void)
{
inpt = kb_buffer; // Initialize buffer
outpt = kb_buffer;
buffcnt = 0;
MCUCR = 2; // INT0 interrupt on falling edge
edge = 0; // 0 = falling edge 1 = rising edge
bitcount = 11;
#asm("sei") // interrupt enable
}
interrupt [EXT_INT0] void INT0_interrupt(void)
{
statIC unsigned char data; // Holds the received scan code
if(bitcount < 11 && bitcount > 2) // Bit 3 to 10 is data. Parity bit,
{ // start and stop bits are ignored.
data = (data >> 1);
if(PIND & 8)
data = data | 0x80; // Store a '1'
}
if(--bitcount == 0) // All bits received
{
decode(data);
bitcount = 11;
}
}
void decode(unsigned char sc)
{
static unsigned char is_up=0, shift = 0, mode = 0;
unsigned char i;
if (!is_up) // Last data received was the up-key identifier
{
switch (sc)
{
case 0xF0 : // The up-key identifier
is_up = 1;
break;
case 0x12 : // Left SHIFT
shift = 1;
break;
case 0x59 : // Right SHIFT
shift = 1;
break;
case 0x05 : // F1
if(mode == 0)
mode = 1; // Enter scan code mode
if(mode == 2)
mode = 3; // Leave scan code mode
break;
default:
if(mode == 0 || mode == 3) // If ASCII mode
{
if(!shift) // If shift not pressed,
{ // do a table look-up
for(i = 0; unshifted[i][0]!=sc && unshifted[i][0]; i++);
if (unshifted[i][0] == sc) {
put_kbbuff(unshifted[i][1]);
}
} else { // If shift pressed
for(i = 0; shifted[i][0]!=sc && shifted[i][0]; i++);
if (shifted[i][0] == sc) {
put_kbbuff(shifted[i][1]);
}
}
} else{ // Scan code mode
