bleat/examples/example_node_eddystone.js

Abstraction library following Web Bluetooth specification for hiding differences in JavaScript BLE APIs

var bluetooth = require('../index').webbluetooth;
var helpers = require('../index').helpers;
var eddystoneUUID = 0xFEAA;

var frameTypes = {
    "UID": 0x00,
    "URL": 0x10,
    "TLM": 0x20
}

var schemes = {
    0x00: "http://www.",
    0x01: "https://www.",
    0x02: "http://",
    0x03: "https://"
}

var expansions = {
    0x00: ".com/",
    0x01: ".org/",
    0x02: ".edu/",
    0x03: ".net/",
    0x04: ".info/",
    0x05: ".biz/",
    0x06: ".gov/",
    0x07: ".com",
    0x08: ".org",
    0x09: ".edu",
    0x0a: ".net",
    0x0b: ".info",
    0x0c: ".biz",
    0x0d: ".gov"
}

function decodeEddystone(view) {
    var type = view.getUint8(0);
    if (typeof type === "undefined") return null;

    if (type === frameTypes.UID) {
        var uidArray = [];
        for (var i = 2; i < view.byteLength; i++) {
            var hex = view.getUint8(i).toString(16);
            uidArray.push(("00" + hex).slice(-2));
        }
        return {
            type: type,
            txPower: view.getInt8(1),
            namespace: uidArray.slice(0, 10).join(),
            instance: uidArray.slice(10, 16).join()
        };
    }

    if (type === frameTypes.URL) {
        var url = "";
        for (var i = 2; i < view.byteLength; i++) {
            if (i === 2) {
                url += schemes[view.getUint8(i)];
            } else {
                url += expansions[view.getUint8(i)] || String.fromCharCode(view.getUint8(i));
            }
        }
        return {
            type: type,
            txPower: view.getInt8(1),
            url: url
        };
    }

    if (type === frameTypes.TLM) {
        return {
            type: type,
            version: view.getUint8(1),
            battery: view.getUint16(2),
            temperature: view.getInt16(4),
            advCount: view.getUint32(6),
            secCount: view.getUint32(10)
        };
    }
}

function handleDeviceFound(bluetoothDevice) {
    var uuid = helpers.getServiceUUID(eddystoneUUID);
    var eddyData = bluetoothDevice.adData.serviceData.get(uuid);
    if (eddyData) {
        var decoded = decodeEddystone(eddyData);
        if (decoded) {
            switch(decoded.type) {
                case frameTypes.UID:
                    console.log("txPower: " + decoded.txPower);
                    break;
                case frameTypes.URL:
                    console.log("url: " + decoded.url);
                    break;
                case frameTypes.TLM:
                    console.log("version: " + decoded.version);
                    break;
            }
        }
    }
}

// Recursively scan
function scan() {
    console.log("scanning...");
    bluetooth.requestDevice({
        filters:[{ services:[ eddystoneUUID ] }],
        deviceFound: handleDeviceFound
    })
    .then(scan)
    .catch(error => {
        console.log(error);
        process.exit();
    });
}
scan();