How to read laser distance measure via web-bluetooth

Question

I need to read distance measurements from a Leica Disto D2 in a Web App using Web Bluetooth API. I'm targeting recent Android devices so Chrome/Samsung Browser should support it.

Answer 1

I've adapted the code from the answer by Mark Robinson, fixed a couple of things and added support for auto-connecting on page refresh

Live demo https://murkle.github.io/utils/webbluetooth/leica_distoD2_laser_measurer.html

// info from https://stackoverflow.com/questions/69629692/how-to-read-laser-distance-measure-via-web-bluetooth
  const DISTO_SERVICEID = '3ab10100-f831-4395-b29d-570977d5bf94';
  const DISTO_DISTANCE = "3ab10101-f831-4395-b29d-570977d5bf94";
  const DISTO_DISTANCE_UNIT = "3ab10102-f831-4395-b29d-570977d5bf94";
  const DISTO_COMMAND = "3ab10109-f831-4395-b29d-570977d5bf94";
  const STATE_RESPONSE = "3ab1010a-f831-4395-b29d-570977d5bf94";
  const DS_MODEL_NAME = "3ab1010c-f831-4395-b29d-570977d5bf94";
  const BATTERY_SERVICE = '0000180f-0000-1000-8000-00805f9b34fb';
  const DEVICE_INFORMATION = '0000180a-0000-1000-8000-00805f9b34fb';

  const namePrefix = "DISTO ";
  let service;
  let device;
  const logElement = document.getElementById('logging'); ;

  function log(message) {
      const logEntry = document.createElement('div');
      logEntry.classList.add('log-entry');
      logEntry.innerText = message;

      logElement.appendChild(logEntry);
  }

  function handleDisconnect() {
      log('Connection lost. Device disconnected.');
      document.getElementById('connectButton').disabled = false;
      document.getElementById('disconnectButton').disabled = true;
      alert('Connection lost. Device disconnected.');
  }

  function disconnectFromDevice() {
      if (device && device.gatt.connected) {
          device.gatt.disconnect();
      }
  }

  function forgetDevice() {
      if (device) {
          device.forget();
      }
  }

  async function discoverDevices() {
      log("discoverDevices");
      let filters = [];

      // filter on EITHER namePrefix OR services
      filters.push({
          namePrefix: namePrefix
      });
      //filters.push({
      //    services: [DISTO_SERVICEID]
      //});

      let options = {
          optionalServices: [DEVICE_INFORMATION, BATTERY_SERVICE, DISTO_SERVICEID],
          acceptAllDevices: false
      }
      options.filters = filters;

      device = await navigator.bluetooth.requestDevice(options);

      log('> Name:' + device.name);
      log('> Id:' + device.id);
      log(device);

      await connectToDevice(device);

      log('Notifications have been started.');
  }

  async function connectToDevice(device) {

      device.addEventListener('gattserverdisconnected', onDisconnected);

      log('Connecting to GATT Server...');
      const server = await device.gatt.connect();

      log('Getting Service...');
      const service = await server.getPrimaryService(DISTO_SERVICEID);

      log('Getting Distance Characteristic...');
      const characteristic = await service.getCharacteristic(DISTO_DISTANCE);
      characteristic.addEventListener('characteristicvaluechanged', handleDistanceChanged);

      log('Enabling notifications...');
      await characteristic.startNotifications();
      log('Connected to ' + device.name);

  }

  function handleDistanceChanged(event) {
      const value = event.target.value;
      log('Got distance: ' + value.getFloat32(0, true));

      document.getElementById("result").innerHTML = "Distance = " + value.getFloat32(0, true).toFixed(4) + " m";
  }
  function onDisconnected(event) {
      const device = event.target;
      log(`Device ${device.name} is disconnected.`);
  }

  function log(message) {
      const logEntry = document.createElement('div');
      logEntry.classList.add('log-entry');
      logEntry.innerText = message;

      logElement.appendChild(logEntry);
  }

  // https://docs.google.com/document/d/1RF4D-60cQJWR1LoQeLBxxigrxJwYS8nLOE0qWmBF1eo/edit
  // try to connect to existing device
  async function getPermittedBluetoothDevices() {
      let devices = await navigator.bluetooth.getDevices();
      for (let device0 of devices) {
          // Start a scan for each device before connecting to check that they're in
          // range.
          let abortController = new AbortController();
          await device0.watchAdvertisements({
              signal: abortController.signal
          });
          device0.addEventListener('advertisementreceived', async(evt) => {
              // Stop the scan to conserve power on mobile devices.
              abortController.abort();

              // Advertisement data can be read from |evt|.
              let deviceName = evt.name;
              let uuids = evt.uuids;
              let appearance = evt.appearance;
              let pathloss = evt.txPower - evt.rssi;
              let manufacturerData = evt.manufacturerData;
              let serviceData = evt.serviceData;

              if (evt.device.name.startsWith(namePrefix)) {

                  log("Found previously connected device " + device0.name)

                  // At this point, we know that the device is in range, and we can attempt
                  // to connect to it.
                  device = evt.device;
                  await connectToDevice(device);
              } else {
                  log("Ignoring device " + device0.name + " as it doesn't start with " + namePrefix);
              }
          });
      }
  }

  getPermittedBluetoothDevices();