bluetoothtest.html

<script>


(async () => {
  try {
    const isBluetoothAvailable = await navigator.bluetooth.getAvailability();
    console.log(`> Bluetooth is ${isBluetoothAvailable ? 'available' : 'unavailable'}`);
  } catch(error) {
    console.log('Argh! ' + error);
  }
})();

if ('onavailabilitychanged' in navigator.bluetooth) {
  navigator.bluetooth.addEventListener('availabilitychanged', function(event) {
    console.log(`> Bluetooth is ${event.value ? 'available' : 'unavailable'}`);
  });
}



function doit() {
  console.log('Requesting any Bluetooth Device...');
  navigator.bluetooth.requestDevice({
   // filters: [...] <- Prefer filters to save energy & show relevant devices.
      acceptAllDevices: true,
      optionalServices: ['d9d9e9e0-aa4e-4797-8151-cb41cedaf2ad']})
  .then(device => {
      console.log('device:', device)
    console.log('Connecting to GATT Server...');
    return device.gatt.connect();
  })
  .then(server => {
    console.log('server:', server)
    console.log('Getting Device Information Service...');
    return server.getPrimaryService('d9d9e9e0-aa4e-4797-8151-cb41cedaf2ad');
    // return server.getPrimaryServices();
  })
  .then(async service => {
    console.log('Getting Characteristics...');
    console.log('service:', service)
    // for (const service of services) {
    //   console.log('> Service: ' + service.uuid);
    const characteristic = await service.getCharacteristic("d9d9e9e1-aa4e-4797-8151-cb41cedaf2ad");
    // const characteristics = await service.getCharacteristics();
    // // const characteristics = service.getCharacteristics();
    // console.log('characteristics:' + characteristics);

    //   mycharacteristic = null;
    //   characteristics.forEach(characteristic => {
    //     console.log('>> Characteristic: ' + characteristic.uuid + ' ' +
    //         getSupportedProperties(characteristic));
    //         console.log('characteristic.uuid:', characteristic.uuid)
    //     if (characteristic.uuid == "d9d9e9e1-aa4e-4797-8151-cb41cedaf2ad") {
    //       console.log('yep!')
    //       mycharacteristic = characteristic;
    //     }
    //   });
    return characteristic;
    // }
    // return service.getCharacteristics();
  })
  .then(async characteristic => {
    console.log('characteristic:', characteristic)

    console.log('Getting Descriptor...');
    // myDescriptor = await characteristic.getDescriptor('gatt.characteristic_user_description');
    myDescriptor = await characteristic.getDescriptor('00002901-0000-1000-8000-00805f9b34fb');
    // myDescriptor = await characteristic.getDescriptor('Bitsnap Control');
    console.log('Descriptor:', myDescriptor)

    // let encoder = new TextEncoder('utf-8');
    let value = "1E0115A364" // beep
    try {
      console.log('Setting Characteristic User Description...');
      // await myDescriptor.writeValue(encoder.encode(value));
      // value = hexDecode(value)
      console.log('initial value:', value)
      value = hexToBytes(value)
      console.log('bytes:', value)
      // newArray = new Uint8Array
      value = new Uint8Array(value).buffer
      // value = value.buffer
      // debugger
      console.log('writing', value)
      
      // await myDescriptor.writeValue(value);
      // await myDescriptor.writeValueWithResponse(value).then(res => {
      await characteristic.writeValueWithResponse(value).then(res => {
        console.log('response:', res)
      })

      // console.log('> Characteristic User Description changed to: ' + value);
    } catch(error) {
      console.log('Argh! ' + error);
    }


  })
//   .catch(error => {
//     console.log('Argh! ' + trace(error));
//   });
}

/* Utils */

function padHex(value) {
  return ('00' + value.toString(16).toUpperCase()).slice(-2);
}

function getSupportedProperties(characteristic) {
  let supportedProperties = [];
  for (const p in characteristic.properties) {
    if (characteristic.properties[p] === true) {
      supportedProperties.push(p.toUpperCase());
    }
  }
  return '[' + supportedProperties.join(', ') + ']';
}



function onGetBluetoothDevicesButtonClick() {
  console.log('Getting existing permitted Bluetooth devices...');
  navigator.bluetooth.getDevices()
  .then(devices => {
    console.log('> Got ' + devices.length + ' Bluetooth devices.');
    for (const device of devices) {
      console.log('  > ' + device.name + ' (' + device.id + ')');
    }
  })
  .catch(error => {
    console.log('Argh! ' + error);
  });
}

function onRequestBluetoothDeviceButtonClick() {
  console.log('Requesting any Bluetooth device...');
  navigator.bluetooth.requestDevice({
 // filters: [...] <- Prefer filters to save energy & show relevant devices.
    acceptAllDevices: true
  })
  .then(device => {
    console.log('> Requested ' + device.name + ' (' + device.id + ')');
  })
  .catch(error => {
    console.log('Argh! ' + error);
  });
}



function hexEncode(input) {
    var hex, i;

    var result = "";
    for (i=0; i<input.length; i++) {
        hex = input.charCodeAt(i).toString(16);
        result += ("0"+hex).slice(-4);
    }

    return result
}

function hexDecode(input) {
    var j;
    var hexes = input.match(/.{1,2}/g) || [];
    var back = new Uint8Array(hexes.length/2);
    console.log('new bytearray length', back.length)
    // debugger
    for(j = 0; j<hexes.length; j++) {
        back[j] = parseInt(hexes[j], 16);
        // back[j] = "\\u"+hexes[j];
        console.log(hexes[j], back[j])
    }

    return back;
}

// Convert a hex string to a byte array
function hexToBytes(hex) {
    for (var bytes = [], c = 0; c < hex.length; c += 2)
    bytes.push(parseInt(hex.substr(c, 2), 16));
    return bytes;
}

// Convert a byte array to a hex string
function bytesToHex(bytes) {
    for (var hex = [], i = 0; i < bytes.length; i++) {
        var current = bytes[i] < 0 ? bytes[i] + 256 : bytes[i];
        hex.push((current >>> 4).toString(16));
        hex.push((current & 0xF).toString(16));
    }
    return hex.join("");
}

</script>




<button onclick="onGetBluetoothDevicesButtonClick()">get devices</button>
<button onclick="onRequestBluetoothDeviceButtonClick()">request device</button>
<button onclick="doit()">do it</button>