Fun with Bluetooth

A presentation at JSConf Belgium in May 2018 in Bruges, Belgium by Niels Leenheer

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fun with bluetooth

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why?

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progressive 
 web apps

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pwa’s are great !

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but...

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ethernet 
 & wifi

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wifi

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zigbee? 


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ethernet

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runs a webserver use fetch or 
 xmlhttprequest

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[{ "id":"001788fffe100491", "internalipaddress":"192.168.2.23", "macaddress":"00:17:88:10:04:91", "name":"Philips Hue" }, { "id":"001788fffe09a168", "internalipaddress":"192.168.88.252" https://www.meethue.com/api/nupnp 1

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<root xmlns="urn:schemas-upnp-org:device-1-0"> <specVersion> <major>1</major> <minor>0</minor> </specVersion> <URLBase>http://192.168.2.23:80/</URLBase> <device> <deviceType>urn:schemas-upnp-org:device:Basic:1</deviceType> <friendlyName>Philips hue (192.168.2.23)</friendlyName> http://192.168.2.23/description.xml 2

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http://192.168.2.23/api 
 {"devicetype": "hue_pwa#pixel_xl"} 3 [{"success":{"username": "........"}}] User presses physical button on the hub click

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http://192.168.2.23/api 
 {"devicetype": "hue_pwa#pixel_xl"} 3 [{"success":{"username": "........"}}] User presses physical button on the hub click

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4 { "1": { "state": { "on": true, "bri": 144, "hue": 13088, "sat": 212, "xy": [0.5128,0.4147], "ct": 467, http://192.168.2.23/api/......../lights

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http://192.168.2.23/api/......../lights/1/state 
 { "hue": 50000, "on": true, "bri": 200 } 5 [ {"success":{"/lights/1/state/bri":200}}, {"success":{"/lights/1/state/on":true}}, {"success":{"/lights/1/state/hue":50000}}

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clickclickreloadclick

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this does 
 not work !

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https only http only no certificate 
 for you

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= network use remote api’s

access to local devices

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hue remote api also allow control from 
 outside the local network

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We are currently preparing for release of this remote API which will initially be available to a limited number of partners. “ — Philips

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We are currently preparing for release of this remote API which will initially be available to a limited number of partners. “ — Philips two years ago very just nest, 
 google assistant 
 and ifttt

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fun with bluetooth problems local networks

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fun with bluetooth

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bluetooth

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bluetooth sucks

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classic bluetooth the reason everybody 
 hates bluetooth bluetooth low energy vs.

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bluetooth low energy also known as BLE Bluetooth LE Bluetooth Smart Bluetooth 4

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bluetooth low energy also known as BLE Bluetooth LE Bluetooth Smart Bluetooth 4 and 5

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10 million


 bluetooth devices 
 shipping every day

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mobile phone

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computer

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glucose monitor somebody's hand

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activity tracker

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playbulb sphere playbulb

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spherio bb-8

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parrot mini drone

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fi dget spinner

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the boring theoretical stuff

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central peripheral

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central

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generic attribute profile

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generic attribute profile ?

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generic attribute profile gatt, because gap was already taken

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client server

central

peripheral

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§ i device information light multiple services per device

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i device information battery flight control

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i device information battery steering control

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i device information battery heart rate

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heart rate

i

device information

battery

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i device information battery heart rate

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i device information manufacturer
model number serial number hardware revision firmware revision software revision ... multiple characteristics 
 per service

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server service characteristic value array of objects object property value

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services and characteristics are identified by uuid’s 16 bit or 128 bit

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0x180A 0000 180A -0000-1000-8000-00805F9B34FB 16 bit 128 bit i device information

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0x180F 0000 180F -0000-1000-8000-00805F9B34FB 16 bit 128 bit battery

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not recommended any UUID outside of the range 
 xxxxxxxx -0000-1000-8000-00805F9B34FB 16 bit 128 bit light steering control flight control still, everybody does this

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i device information manufacturer
model number serial number hardware revision firmware revision software revision ...

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i 0x180A 0x2A29
0x2A24 0x2A25 0x2A27 0x2A26 0x2A28 ... bad for readability, 
 good for saving bandwidth

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read write write without response notify each characteristic supports
one or more of these

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every value is an array of bytes no fancy datatypes, just bytes

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pfew...

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fun

with

bluetooth boring facts 
 about

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fun with bluetooth

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 web


 bluetooth
api still not the fun part :-(

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connecting to a device

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navigator.bluetooth.requestDevice({ filters: [
{ namePrefix: 'PLAYBULB' }
], optionalServices: [ 0xff0f ] }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(characteristic => { return characteristic.writeValue( new Uint8Array([ 0x00, r, g, b ]) ); }) 1 we tell the browser what 
 kind of device we want

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the user selects
the actual device

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navigator.bluetooth.requestDevice({ filters: [
{ namePrefix: 'PLAYBULB' }
], optionalServices: [ 0xff0f ] }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(characteristic => { return characteristic.writeValue( new Uint8Array([ 0x00, r, g, b ]) ); }) 2 connect to the server

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navigator.bluetooth.requestDevice({ filters: [
{ namePrefix: 'PLAYBULB' }
], optionalServices: [ 0xff0f ] }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(characteristic => { return characteristic.writeValue( new Uint8Array([ 0x00, r, g, b ]) ); }) get the service 3

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navigator.bluetooth.requestDevice({ filters: [
{ namePrefix: 'PLAYBULB' }
], optionalServices: [ 0xff0f ] }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(characteristic => { return characteristic.writeValue( new Uint8Array([ 0x00, r, g, b ]) ); }) get the characteristic 4

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writing data

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navigator.bluetooth.requestDevice({ ... }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(c => { return c.writeValue( new Uint8Array([ 0x00, r, g, b ]) ); }) write some bytes

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reading data

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navigator.bluetooth.requestDevice({ ... }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(c => c.readValue()) .then(value => { let r = value.getUint8(1);
let g = value.getUint8(2); let b = value.getUint8(3); }) read some bytes

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get notified of changes

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navigator.bluetooth.requestDevice({ ... }) .then(device => device.gatt.connect()) .then(server => server.getPrimaryService(0xff0f)) .then(service => service.getCharacteristic(0xfffc)) .then(c => { c.addEventListener('characteristicvaluechanged', e => { let r = e.target.value.getUint8(1);
let g = e.target.value.getUint8(2); let b = e.target.value.getUint8(3); }); c.startNotifications(); }) don't forget to start listening

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things you need to know: • the webbluetooth api • promises • typed arrays duh!

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browser support Chrome Opera Samsung Servo 
 (soon)

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browser support Safari Chrome Opera Samsung Servo 
 (soon)

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browser support Chrome Opera Samsung Servo 
 (soon) Safari

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browser support kinda works WebBLE 
 for iOS Chrome Opera Samsung Servo 
 (soon)

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and...

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and... npm install node-web-bluetooth

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and... npm install cordova-plugin-webbluetooth

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and... the puck.js

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custom
characteristics . wtf!

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writing a value: function(r, g, b) { return new Uint8Array([ 0x00, r, g, b ]); } reading a value: function(buffer) { return { 
 r: buffer.getUint8(1), 
 g: buffer.getUint8(2), 
 b: buffer.getUint8(3) 
 } }

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writing a value: function(r, g, b) { return new Uint8Array([
0x01, g, 0x01, 0x00, 0x01, 
 b, 0x01, r, 0x01, 0x00

 ]); } reading the current 
 color is not possible

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writing a value: 
 function(r, g, b) { var buffer = new Uint8Array([ 
 0xaa, 0x0a, 0xfc, 0x3a, 0x86, 0x01, 0x0d, 
 0x06, 0x01, r, g, b, 0x00, 0x00, 
 (Math.random() * 1000) & 0xff, 0x55, 0x0d 
 ]); for (var i = 1; i < buffer.length - 2; i++) { buffer[15] += buffer[i]; } return buffer; }

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writing a value: 
 function(r, g, b, position) { let buffer = new Uint8Array([
0x07, 0x02, position + 1, r, g, b
]); return buffer; }

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writing a value: 
 function(r, g, b, position) { let buffer = new Uint8Array([
0x58, r, g, b, 0x01, position ]); ...

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writing a value: 
 function(r, g, b, position) { let buffer = new Uint8Array([
0x58, r, g, b, 0x01, position ]); let payload = new Uint8Array(buffer.length + 4); payload[0] = payload.length - 2; payload[1] = payload.length - 2 >>> 8; payload.set(buffer, 2); let checksum = payload.reduce((a, b) => a + b, 0); payload[payload.length - 2] = checksum; payload[payload.length - 1] = checksum >>> 8; let extra = payload.filter(value => { 


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    else if (payload[i] === 0x03) { 
        message[m] = 0x03; 
        message[m + 1] = 0x06; 
        m += 2; 
    } 
    else { 
        message[m] = payload[i]; 
        m++; 
    } 
} 
message[0] = 0x01; 
message[message.length - 1] = 0x02; 
return message; 

}

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adafruit 
 bluetooth 
 sniffer

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decompiling


 the apk don't tell anyone!

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demofinally the fun part

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warning experimental technology 
 setting low expectations

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warning wifi interference 
 lowering them even further

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#jsconfbe

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https://bluetooth.rocks/lightbulb 
 https://github.com/BluetoothRocks/Lightbulb change the colour 
 of a lightbulb

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https://bluetooth.rocks/pixel 
 https://github.com/BluetoothRocks/Matrix draw pixel art on 
 a led matrix display

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https://bluetooth.rocks/racer https://github.com/BluetoothRocks/Racer control a lego racer 
 using a gamepad use css animations to 
 define a path

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https://bluetooth.rocks/drone 
 https://github.com/BluetoothRocks/Drone control a drone 
 from your browser

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https://bluetooth.rocks/printer 
 https://github.com/BluetoothRocks/TweetPrinter print on a receipt printer

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https://bluetooth.rocks/pulse 
 https://github.com/BluetoothRocks/Pulsefind out your 
 current heartbeat

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fun with bluetooth !

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questions? @html5test