source: avrstuff/kbd/pcwk/code/main.c@ a3eb2c6

#define F_CPU 16000000UL

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>

#include "../../libs/ps2_keyboard/ps2_keyboard.h"

uint8_t keys[16];

const uint8_t pcw[128] PROGMEM = {
// 0   1   2   3    4    5    6    7    8    9    A    B    C    D    E    F
'?' ,0x20,'?' ,0xA0,0x00,0x02,'?' ,0x12,'?' ,0x03,0xA4,'?' ,'?' ,0x84,0x26,'?', // 0
'?' ,0xA7,0x26,'?' ,0xA1,0x83,0x80,'?' ,'?' ,'?' ,0x87,0x74,0x85,0x73,0x81,'?', // 1
'?' ,0x76,0x77,0x75,0x72,0x70,0x71,'?' ,'?' ,0x57,0x67,0x65,0x63,0x62,0x61,'?', // 2
'?' ,0x56,0x66,0x54,0x64,0x53,0x60,'?' ,'?' ,'?' ,0x46,0x55,0x52,0x51,0x50,'?', // 3
'?' ,',' ,0x45,0x43,0x42,0x40,0x41,'?' ,'?' ,0x37,0x23,0x44,0x35,0x33,0x31,'?', // 4
'?' ,'?' ,'?' ,0x11,0x32,0x30,'?' ,'?' ,0x86,0x25,0x22,0x21,0x36,0x34,'?' ,'?', // 5
'?' ,'?' ,'?' ,'?' ,'?' ,'?' ,0x97,'?' ,'?' ,0x17,'?' ,0x15,0x24,'?' ,'?' ,'?', // 6
0x01,0xA6,0x07,0x16,0x05,0x14,0x82,0xA5,0x13,0x27,0x06,0xA3,0xA2,0x04,0x10,'?'  // 7
};


void callback()
{
        uint8_t key_code = 0;
        key_code = read_char(); // TODO this is blocking function

        uint8_t decode = pgm_read_byte(&(pcw[key_code]));
        if(release)
                keys[decode >> 4] &= ~(1 << (decode & 0xF));
        else
                keys[decode >> 4] |= 1 << (decode & 0xF);
}


int main() {
  init_keyboard(); 

  // PCW init - configure pins directions
  PORTB = 0;
  DDRB = 0x6; // PB1 and PB2 as outputs

  //debug LED - output
  DDRD |= (1<<PD6);


  while(1) {
        for(int idx = -1; idx < 16; idx++)
        {
                // send data to PCW
                
                // Start pulse
                PORTB = 4;
                _delay_us(6);
                PORTB = 0;
                _delay_us(6);
                PORTB = 4;
                _delay_us(6);
                PORTB = 0;
                _delay_us(6);

                // Address
                for(int j = 4; --j >= 0;)
                {
                        if(idx & (1<<j))
                                PORTB = 4;
                        else
                                PORTB = 0;

                        // Clock
                        _delay_us(6);
                        PORTB |= 2;
                        _delay_us(12);
                        PORTB = 0;
                        _delay_us(21);
                }

                // One "empty" clock cycle
                _delay_us(21 + 33);

                // Data
                for(int j = 8; --j >= 0;)
                {
                        if (keys[idx & 0xF] & (1 << j)) 
                                PORTB = 4;
                        else
                                PORTB = 0;

                        // Clock
                        _delay_us(6);
                        PORTB |= 2;
                        _delay_us(12);
                        PORTB = 0;
                        _delay_us(21);
                }
        }
  }
  
  return 0;
}