PS/2 keyboard reader and Gradiente Expert 1.1 MSX keyboard adapter

ps2_msx.ino

/*
 * ABNT2 PS/2 keyboard to Gradiente Expert 1.1 keyboard mapper
 * (c) 2014 Tiago Rezende
 */

static const uint8_t ps2data = 2;
static const uint8_t ps2clk = 3;

//#define K(x) (uint8_t)((x>=0x80)?(x+0x8):((x<=0x07)?(x+0x80):(x-0x10)))
#define K(x) x
const PROGMEM uint8_t keymap_ABNT2[] = {
  K(0xb7),
  K(0xb7), // F9
  K(0xb7),
  K(0x71), // F5
  K(0x67), // F3
  K(0x65), // F1
  K(0x66), // F2
  K(0xb7), // F12
  
  K(0xb7),
  K(0xb7), // F10
  K(0xb7), // F8
  K(0xb7), // F6
  K(0x70), // F4
  K(0x73), // TAB
  K(0xb7), // `
  K(0xb7),
  
  K(0xb7),
  K(0x64), // L ALT
  K(0x60), // L SHIFT
  K(0xb7),
  K(0x61), // L CTRL
  K(0x46), // Q
  K(0x01), // 1
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0x57), // Z
  K(0x50), // S
  K(0x26), // A
  K(0x54), // W
  K(0x02), // 2
  K(0xb7), // L WIN
  
  K(0xb7),
  K(0x30), // C
  K(0x55), // X
  K(0x31), // D
  K(0x32), // E
  K(0x04), // 4
  K(0x03), // 3
  K(0xb7),
  
  K(0xb7),
  K(0x80), // SPACE
  K(0x53), // V
  K(0x33), // F
  K(0x51), // T
  K(0x47), // R
  K(0x05), // 5
  K(0xb7),
  
  K(0xb7),
  K(0x43), // N
  K(0x27), // B
  K(0x35), // H
  K(0x34), // G
  K(0x56), // Y
  K(0x06), // 6
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0x42), // M
  K(0x37), // J
  K(0x52), // U
  K(0x07), // 7
  K(0x10), // 8
  K(0xb7),
  
  K(0xb7),
  K(0x22), // ,
  K(0x40), // K
  K(0x36), // I
  K(0x44), // O
  K(0x00), // 0
  K(0x11), // 9
  K(0xb7),
  
  K(0xb7),
  K(0x23), // .
  K(0x24), // ;
  K(0x41), // L
  K(0x21), // Ç
  K(0x45), // P
  K(0x12), // -
  K(0xb7),
  
  K(0xb7),
  K(0x25), // /
  K(0x17), // ~
  K(0xb7),
  K(0x15), // ´
  K(0x13), // =
  K(0xb7),
  K(0xb7),
  
  K(0x63), // CAPS
  K(0x60), // R SHIFT
  K(0x77), // ENTER
  K(0x16), // [
  K(0xb7),
  K(0x21), // ]
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0x14), // \  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0x75), // BACKSPACE
  
  K(0xb7),
  K(0xb7),
  K(0x01), // KEYPAD 1,
  K(0xb7),
  K(0x04), // KEYPAD 4,
  K(0x07), // KEYPAD 7,
  K(0x23), // KEYPAD .
  K(0xb7),
  
  K(0xb7),
  K(0x00), // KEYPAD 0
  K(0x22), // KEYPAD ,
  K(0x02), // KEYPAD 2
  K(0x05), // KEYPAD 5
  K(0x06), // KEYPAD 6
  K(0x10), // KEYPAD 8
  K(0x72), // ESCAPE
  
  K(0xb7), // NUMLOCK
  K(0xb7), // F11
  K(0x90), // KEYPAD +
  K(0x03), // KEYPAD 3
  K(0x91), // KEYPAD -
  K(0x92), // KEYPAD *
  K(0x11), // KEYPAD 9,
  K(0xb7), // SCROLL LOCK
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // F7
};

const PROGMEM uint8_t keymap_ext_ABNT2[] = {
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7), // WWW SEARCH
  K(0x62), // R ALT
  K(0xb7), // PRINT SCREEN
  K(0xb7),
  K(0x42), // R CTRL
  K(0xb7), // PREV TRACK
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0x62), // L WIN
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // MESSENGER
  K(0xb7),
  K(0xb7), // R WIN
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // CALC
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0x80), // CONTEXT
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // PLAY/PAUSE
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0xb7), // WWW HOME
  K(0xb7), // STOP
  K(0xb7), // LOG OFF
  K(0xb7),
  K(0xb7),
  K(0xb7), // SLEEP
  
  K(0xb7), // MY COMPUTER
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7), // EMAIL
  K(0xb7),
  K(0x94), // KEYPAD /
  K(0xb7),
  K(0xb7),
  K(0xb7), // NEXT TRACK
  K(0xb7),
  K(0xb7),
  
  K(0xb7), // MEDIA SELECT
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0x77), // KP EN
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // WAKE
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7), // END
  K(0xb7),
  K(0x84), // L ARROW
  K(0x81), // HOME
  K(0xb7),
  K(0xb7),
  K(0xb7),
  
  K(0x82), // INSERT
  K(0x83), // DELETE
  K(0x86), // D ARROW
  K(0xb7),
  K(0x87), // R ARROW
  K(0x85), // U ARROW
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0x76), // PAGE DOWN
  K(0xb7),
  K(0xb7),
  K(0x74), // PAGE UP
  K(0xb7),
  K(0xb7),
  
  K(0xb7),
  K(0xb7),
  K(0xb7),
  K(0xb7), // F7
};

uint8_t msx_buffer[16];
  


#define CO_BEGIN static int _co_state = 0; switch(_co_state) { case 0:
#define CO_WAIT(x) case __LINE__: if((x)) { _co_state = __LINE__; return; };
#define CO_YIELD do {_co_state = __LINE__; return; } while(0); case __LINE__: ;
#define CO_END };

#define CO_WAIT_HIGH(x) CO_WAIT(digitalRead(x) == 0)
#define CO_WAIT_LOW(x) CO_WAIT(digitalRead(x) != 0)


static inline void ps2kbd_interrupt(void) {
  static uint8_t bitcount = 0, incoming = 0;
  static uint32_t prev_ms = 0;
  static boolean release_key, use_extended;
  uint32_t now_ms;
  uint8_t n, val;
  
  val = digitalRead(ps2data);
  now_ms = millis();
  if(now_ms - prev_ms > 250) {
    bitcount = 0;
    incoming = 0;
  }
  prev_ms = now_ms;
  n = bitcount - 1;
  if (n <= 7) {
    incoming = (val?0x80:0)|(incoming >> 1);
  }
  bitcount ++;
  if(bitcount == 11) {
    if(incoming == 0xf0) {
      release_key = true;
    } else if(incoming == 0xe0) {
      use_extended = true;
    } else {
      uint8_t msx_scancode = pgm_read_byte(use_extended?(keymap_ext_ABNT2+incoming):(keymap_ABNT2+incoming));
      if(release_key) {
        msx_buffer[msx_scancode>>4] |= (1 << (msx_scancode & 0xf));
      } else {
        msx_buffer[msx_scancode>>4] &= ~(1 << (msx_scancode & 0xf));
      }
      /*
      Serial.println(incoming);
      /*
      for(int i = 0; i < 16; i++) {
        Serial.print(msx_buffer[i]>>4,HEX);
        Serial.print(msx_buffer[i]&0xf,HEX);
      }
      Serial.println();
      //*/
      use_extended = false;
      release_key = false;
    }
    bitcount = 0;
    incoming = 0;
  }
}
void ps2kbd_poll() {
  static uint8_t incoming, i, outgoing, parity;
  CO_BEGIN;
  
  /*
  pinMode(ps2data, OUTPUT);
  digitalWrite(ps2data, 0);
  pinMode(ps2clk, INPUT_PULLUP);
  CO_WAIT_LOW(ps2clk);
  outgoing = 0xff;
  parity = 0;
  for(i = 0; i < 8; i++) {
    parity += outgoing & 1;
    digitalWrite(ps2data, outgoing & 1);
    CO_WAIT_HIGH(ps2clk);
    CO_WAIT_LOW(ps2clk);
    outgoing >>= 1;
  }
  digitalWrite(ps2data, parity & 1);
  CO_WAIT_HIGH(ps2clk);
  CO_WAIT_LOW(ps2clk);
  digitalWrite(ps2data, 1);
  CO_WAIT_HIGH(ps2clk);
  CO_WAIT_LOW(ps2clk);
  
  
  delayMicroseconds(50);
  //CO_WAIT_LOW(ps2clk);
  pinMode(ps2data, INPUT_PULLUP);
  */
  while(true) {
    CO_WAIT_HIGH(ps2clk);
    CO_WAIT_LOW(ps2clk);
    ps2kbd_interrupt();
  }
  CO_END;
}

void setup() {
  //Serial.begin(9600);
  //while(!Serial) {;}
  pinMode(ps2data, INPUT_PULLUP);
  pinMode(ps2clk, INPUT_PULLUP);
  
  pinMode(4, INPUT_PULLUP);
  pinMode(5, INPUT_PULLUP);
  pinMode(6, INPUT_PULLUP);
  pinMode(7, INPUT_PULLUP);

  pinMode(A0,  OUTPUT);
  pinMode(A1,  OUTPUT);
  pinMode(A2,  OUTPUT);
  pinMode(A3,  OUTPUT);
  
  pinMode(8,  OUTPUT);
  pinMode(9,  OUTPUT);
  pinMode(10,  OUTPUT);
  pinMode(11,  OUTPUT);

  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);

  for(uint8_t i = 0; i < 16; i++) {
    msx_buffer[i] = 255;
  }
  attachInterrupt(1, ps2kbd_interrupt, FALLING);
}

void loop() {
  uint8_t last_keys_index = 20;
  uint8_t current;
  uint8_t keys = 0;
  PORTC &= 0xf0;
  PORTB &= 0xf0;
  while(true) {
    while(last_keys_index == (current = __builtin_avr_swap(PIND)&0xf)) {
      sei();
      delayMicroseconds(1);
      cli();
    }
    keys = msx_buffer[current];
    PORTC = keys;
    PORTB = __builtin_avr_swap(keys);
    last_keys_index = current;
   }
}