This document discusses using Android Things and the Google Assistant for home automation. It provides examples of controlling smart home devices like lights and switches through actions, traits, and device syncing. Code samples are given for communicating with devices over Bluetooth, GPIO, UART, and infrared to control lights, fans, outlets and more. Additional resources are provided on building smart home apps with Actions on Google and reverse engineering protocols for interoperability.

1. Home Automation with
Android Things and the
Google Assistant

2. Android is everywhere

4. Google Assistant Shoebox Robot(01)
(01)
http://nilhcem.com/android-things/create-your-google-assistant-robots

5. In your Home?

7. OK Google,

9. Philips Hue Bridge

13. https://developers.google.com/actions/

17. OAuth2 server

20. Device Actions
• SYNC
• EXECUTE
• QUERY

21. SYNC Request:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"inputs": [{
"intent": "action.devices.SYNC"
}]
}

22. SYNC Response:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"payload": {
"devices": [{
"id": "1",
"type": "action.devices.types.LIGHT",
"traits": [
"action.devices.traits.OnOff",
"action.devices.traits.ColorSpectrum"
],
"name": {
"name": "Lightbulb"
},
"willReportState": true
}]
}
}

23. Device types:
Camera Refrigerator
Dishwasher Switch
Dryer Thermostat
Light Vacuum
Outlet Washer

24. Device traits:
Brightness OnOff
CameraStream RunCycle
ColorSpectrum Scene
ColorTemperature StartStop
Dock TemperatureSetting
Modes Toggles

25. "Ok Google,
"

26. Smart Home Device Traits(03)
(03)
https://developers.google.com/actions/smarthome/traits/

27. https://cloud.google.com/functions/?hl=ja

28. exports.ha = function(req, res) {
if (!isAuthTokenValid(req)) return;
let intent = req.body.inputs[0].intent;
switch (intent) {
case 'action.devices.SYNC':
sync(req, res);
break;
case 'action.devices.EXECUTE':
execute(req, res);
break;
case 'action.devices.QUERY':
query(req, res);
break;
}
};

29. function sync(req, res) {
res.status(200).json({
requestId: req.body.requestId,
payload: {
devices: [{
id: 'lightbulb',
type: 'action.devices.types.LIGHT',
traits: [
'action.devices.traits.OnOff',
'action.devices.traits.ColorSpectrum'
],
name: {
name: 'Lightbulb'
},
willReportState: true
}]
}
});
}

30. $ gcloud beta functions deploy ha --trigger-http

31. https://us-central1-your-id.cloudfunctions.net/ha

34. Device Actions
• SYNC
• EXECUTE
• QUERY

35. EXECUTE Request:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"inputs": [{
"intent": "action.devices.EXECUTE",
"payload": {
"commands": [{
"devices": [{
"id": "lightbulb"
}],
"execution": [{
"command": "action.devices.commands.OnOff",
"params": {
"on": true
}
}]
}]
}
}]
}

36. EXECUTE Response:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"payload": {
"commands": [{
"ids": ["lightbulb"],
"status": "SUCCESS",
}]
}
}

37. Device Actions
• SYNC
• EXECUTE
• QUERY

39. QUERY Request:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"inputs": [{
"intent": "action.devices.QUERY",
"payload": {
"devices": [{
"id": "lightbulb"
}]
}
}]
}

40. QUERY Response:
{
"requestId": "ff36a3cc-ec34-11e6-b1a0-64510650abcf",
"payload": {
"devices": {
"lightbulb": {
"on": false,
"online": true,
"color": {
"spectrumRGB": 16777215
}
}
}
}
}

43. Raspberry Pi 3

55. FirestoreLiveData.kt
class FirestoreLiveData : LiveData<Device>() {
override fun onActive() {
authenticateWithFirebase { user ->
listenForFirestoreChanges("users/${user.uid}/devices") { change ->
postValue(change)
}
}
}
}

57. const admin = require('firebase-admin');
admin.initializeApp({
credential: admin.credential.applicationDefault()
});

58. var db = admin.firestore();
var docRef = db.doc(`users/${userId}/devices/lightbulb`);
docRef.set({ on: true, spectrumRGB: 255 });

59. Lightbulbs

60. Bluetooth lightbulbs

61. Reverse engineering
Bluetooth Low Energy devices(04)
(04)
http://nilhcem.com/iot/reverse-engineering-simple-bluetooth-devices

62. Capture Bluetooth packets

64. $ adb pull /sdcard/Android/data/btsnoop_hci.log

66. • Value: 56RRGGBB00f0aa
• Characteristic: ffe9
• Service: ffe5

68. Android Things app

69. Converting a color to a ByteArray
private fun colorToByteArray(color: Int): ByteArray {
val red = Color.red(color)
val green = Color.green(color)
val blue = Color.blue(color)
return byteArrayOf(0x56, red, green, blue, 0x00, 0xf0, 0xaa)
}

70. Send the color data to the lightbulb
private fun writeCharacteristic(gatt: BluetoothGatt, color: Int) {
val service = gatt.getService(SERVICE_UUID) // 0xFFE5
val characteristic = service.getCharacteristic(CHARACTERISTIC_UUID) // 0xFFE9
characteristic.value = colorToByteArray(color)
gatt.writeCharacteristic(characteristic)
}

71. MainActivity.kt
firestoreLiveData.observe({ lifecycle }) { device ->
when (device) {
is Lightbulb -> lightbulb.updateState(device)
}
}

76. Update Firestore

77. Fan + Relay module

78. Android Things GPIO API
viewModel.firestoreLiveData.observe({ lifecycle }) { device ->
when (device) {
is Lightbulb -> lightbulb.onStateChanged(device)
is Fan -> relay.value = device.isOn
}
}

79. Radio-controlled Power Outlets

80. Radio Frequency Emitter / Receiver(05)
(05)
https://github.com/Nilhcem/home-automation-talk-resources/tree/master/radio-power-outlet

82. Android Things UART API
private fun on() = sendUart('1')
private fun off() = sendUart('0')
private fun sendUart(char: Char) {
uartDevice?.write(byteArrayOf(char.toByte()), 1)
}
private fun openUart() {
uartDevice = PeripheralManagerService().openUartDevice(UART_NAME).apply {
setBaudrate(9600)
setDataSize(8)
setParity(UartDevice.PARITY_NONE)
setStopBits(1)
}
}

83. Infrared blaster

84. Infrared Receiver (VS1838B)(06)
(06)
https://github.com/Nilhcem/home-automation-talk-resources/tree/master/infrared-lamp/01-arduino_receiver

85. Infrared Receiver (VS1838B)

86. Infrared dump
Encoding : UNKNOWN
Code : E318261B (32 bits)
Timing[67]:
+8950, -4550 + 500, - 650 + 500, - 650 + 500, - 650
+ 500, - 650 + 500, - 650 + 500, - 650 + 500, - 650
+ 500, - 650 + 500, -1750 + 500, -1700 + 500, -1800
+ 450, -1750 + 450, -1800 + 450, -1750 + 450, -1750
+ 500, -1750 + 450, -1750 + 500, - 650 + 500, -1750
+ 500, - 650 + 500, - 650 + 500, - 650 + 500, -1750
+ 450, - 700 + 450, - 700 + 450, -1750 + 500, - 700
+ 450, -1750 + 500, -1700 + 500, -1750 + 500, - 650
+ 500, -1750 + 450
unsigned int rawData[67] = {8950,4550, 500,650, 500,650, 500,650, 500,650,
500,650, 500,650, 500,650, 500,650, 500,1750, 500,1700, 500,1800, 450,1750,
450,1800, 450,1750, 450,1750, 500,1750, 450,1750, 500,650, 500,1750, 500,650,
500,650, 500,650, 500,1750, 450,700, 450,700, 450,1750, 500,700, 450,1750,
500,1700, 500,1750, 500,650, 500,1750, 450}; // UNKNOWN E318261B

87. ESP8266(07)
(07)
https://github.com/Nilhcem/home-automation-talk-resources/tree/master/infrared-lamp/03-
esp8266_transmitter

88. Retrofit call
@GET("color/{code}")
fun setBulbColor(@Path("code") code: Char): Call<Any>

90. Takeaway
• Actions on Google for chatbots & smart home apps. For
companies & individuals
• Android Things simplifies building secured & advanced IoT
devices
• Create your own devices, or hack existing ones for
interoperability
• Easier than it seems

91. Additional information
• Source code for all the projects:
https://github.com/Nilhcem/home-automation-talk-resources
• Home automation with the Google Assistant:
http://nilhcem.com/android-things/google-assistant-smart-home
• Actions on Google Smart Home documentation:
https://developers.google.com/actions/smarthome/
• Reverse engineering BLE devices:
http://nilhcem.com/iot/reverse-engineering-simple-bluetooth-devices
• Reverse engineering IR devices:
http://nilhcem.com/iot/reverse-engineering-ir-rgb-bulb

92. Home Automation with
Android Things and the
Google Assistant
• Twitter: @Nilhcem