nfc

I’ve recently started a project where I wanted to use NFC for a two way communication between a phone and device. For this reason I changed the Espruino NFC API to expose low level hardware access in JS. To prevent conflicts with Nordic's driver I completely removed support for NRF.nfcRaw and NRF.nfcURL. My branch instead features:

//Enable NFC (returns tag header, 10 bytes)
>NRF.nfcStart();
=new ArrayBuffer([95, 42, 58, 199, 216, 35, 65, 189, 7, 3])

//Disable NFC
NRF.nfcStop();

//Register callback to call with incoming data
NRF.on('NFCrx', function(data) { ... }

//Send response
NRF.nfcSend(new Uint8Array([0x01, 0x02, 0x03, 0x04, ...]);
//Send ACK
NRF.nfcSend(0xA);
//Send NACK
NRF.nfcSend(0x0);
//No response, wait for next command
NRF.nfcSend();

Below is a usage example that "implements" NRF.nfcURL("http://espruino.com"):

var ndef = new Uint8Array([
  0x00, 0x00, 0x00, 0x00, // |      UID/BCC      | TT = Tag Type
  0x00, 0x00, 0x00, 0x00, // |      UID/BCC      | ML = NDEF Message Length
  0x00, 0x00, 0xFF, 0xFF, // | UID/BCC |   LOCK  | TF = TNF and Flags
  0xE1, 0x11, 0x7C, 0x0F, // |  Cap. Container   | TL = Type Legnth
  0x03, 0x14, 0xC1, 0x01, // | TT | ML | TF | TL | RT = Record Type
  0x00, 0x00, 0x00, 0x0D, // |  Payload Length   | IC = URI Identifier Code
  0x55, 0x03, 0x65, 0x73, // | RT | IC | Payload | Payload, see nfcRaw ex.
  0x70, 0x72, 0x75, 0x69, // |      Payload      |
  0x6E, 0x6F, 0x2E, 0x63, // |      Payload      |
  0x6F, 0x6D, 0xFE,       // | Payload | TB |    | TB = TLV Term Block
]);

//Start NFC
var header = NRF.nfcStart();
//Inject UID/BCC into NDEF template
ndef.set(header, 0);

NRF.on('NFCrx', function(rx) {
  if(rx[0] === 0x30) { //Command: READBLOCK
    //Calculate block index
    var idx = rx[1]*4;

    //prepare data (pad to 16 bytes)
    var view = new Uint8Array(ndef.buffer, idx, 16);
    var tx = Uint8Array(16);
    tx.set(view, 0);

    //send response
    NRF.nfcSend(tx);
  } else {
    print("Unknown command: " + rx);
    //wait for next frame
    NRF.nfcSend();
  }
});

I hope my extensions are of use for the projects discussed above.

https://github.com/drandreas/Espruino/re­leases