RFID reader

Readme.md

Espruino javascript code to poll for serial number of RFID card. Since the reader communicates over UART, should work with other controllers that have UART, such as the Raspberry Pi.

Works with MFRC500-based RFID Reader/Writer - 13.56Mhz

• Diagram of board
• Arduino tutorial and sketch

Pinout

   .-----------------------------.
   | [1][2]      [5][4][3][2][1] |
   |  J3              J1         |
   |                             |
   |           RDM880 (top view) |
   |                             |
   |                  J2         |
   |             [5][4][3][2][1] |
   .-----------------------------.

RFID Breakout pin	Espruino pin
J2 5	Bat
J2 4	GND
J2 3	C11
J2 2	C10

rfid.js

Serial4.setup(9600);

var Cmd = {
    start: 0xAA
  , ok   : 0x00
  , end  : 0xBB
};

var debug = false;

var query = [Cmd.start, 0x00, 0x03, 0x25, 0x26, 0x00, 0x00, Cmd.end];

function parseData(string) {
  return string
    .split('')
    .map (
      function (c) { return c.charCodeAt (0); }
    );
}

function hex(num) {
  return (num < 10 ) ? '0' + num : num.toString(16);
}

function hexString(array) {
  return array
    .map(hex)
    .join('');
}

var buffer = [];

var lastTagId = null;

function done(id) {
  if (id && lastTagId != id) {
    lastTagId = id;
    print(id);
  } else if (id == null && lastTagId != null) {
    lastTagId = null;
    print('Removed');
    //print('no tags readable');
  }
  setTimeout(doQuery, 0);
}

function parseResponse(b) {
  if (debug) { print(b); }

  var status = b[3],
      numTags = b[4],
      id = [];

  if (status == Cmd.ok) {
    if (debug) { print('read: ok'); }

    if (debug) { print(numTags); }

    if (debug) {
      switch(numTags) {
        case 0x00: print('one tag readable');
          break;
        case 0x01: print('at least 2 tags readable');
          break;
      }
    }

    id = b.slice(5, 9);
    if (debug) { print('ID: ' + id); }

    id = hexString(id);

    done(id);
  } else {
    done();
  }

}

function receive(data) {

  var parsed = parseData(data);

  buffer = buffer.concat(parsed);

  if (debug) { print(parsed); }

  if (buffer.indexOf(Cmd.end) > -1) {
    parseResponse(buffer);
    buffer = [];
  }
}

Serial4.on('data', receive);


function doQuery () {
  Serial4.write(query);
}

// Start polling
done();