Android Things is a customized version of Android OS designed for building embedded and IoT devices. It features a lightweight version of Google Play Services, support for Bluetooth Low Energy and peripheral device drivers, and over-the-air updates. Apps are developed using Android Studio and deployed via ROM updates instead of an app store. The OS also supports connecting to sensors, buttons, displays and other hardware through drivers and custom C/C++ code.

1. Android Things
Smart Home
#cododajnia
Bartosz Kosarzycki
@bkosarzycki
Michał Radtke
Feb 22, 2018

3. Operating System
- Customized version of Android OS
- announced at Google I/O 2015, codename: “Brillo”
- based on Android 7.0+ (currently 8.0+)
- “kiosk” mode
- theoretically supports devices with 64 MB RAM
- Bluetooth Low Energy support*
- custom Launcher for IoT configuration
- Single application mode
automatically boots into main application
* Feb 2018 - Android Things is still in beta

4. Operating System
- Customized version of Android OS
- “light” version Google Play Services
- no app store - apps installed via ROM updates
- drivers for peripheral devices

5. Operating System
Android Things
Thinned down Android OS with a custom
launcher and KIOSK mode

6. ROM updates
- Google generates initial image
- Handles update integrity/signing verification
- OTA updates
- Automatically reverts
previous version if update fails

7. Operating System
* display is entirely optional

8. Hardware
- SOM architecture
- Base board + certified modules
- Custom hardware through pins/connectors/serials
SOM - System-on-a-chip
SiP - System-in-package (stacked SOMs)
- Easy certification (CE - EU declaration of conformity)

9. Supported platforms

10. Android vs Android Things
- There is no Play Store
- Users cannot install apps on their own
- App updates provided with OTA updates
- No system application drawer
- No notifications
- UI is optional

11. Smart home
Firebase cloud:
● fast
● callbacks
● All mobile platforms
support -
iOS/Android/
Android Things

12. Preparation
- SDCard min. 4 GB
- Raspberry PI ver. 3
- AC adapter
ACa

13. ROM flashing
- Prepare custom ROM from
Android Things Developer Console
ACa

14. Development
- Android Things is open source (still in preview)
link
No need to compile custom ROM & custom launcher
In most cases we only need to develop application
& services
However, we can do that by cloning:
repo init -u https://android.googlesource.com/platform/manifest -b
android-o-iot-preview-5
repo sync

15. Development
- No emulator is provided at this stage (preview)
- UI can be developed as a regular Android app
- If no display is available - screen mirroring from Android
e.g. Vysor link
android:required="false"

16. Development
- Steep learning curve
(easy for a mobile-developer)
- Use usual Android UI, libraries & tools
- Kotlin / RxJava etc.
- Apps developed in
Android Studio
- Built-in security

17. Development - ADB over Wifi
Find raspberry ip address:

18. Development - Permissions / Wifi
- Permissions are granted at app boot
(no Android 6.0+ runtime permission support)
- Usually you need to restart the device after adding a new
permission
- After connecting to a WiFi network - AT reconnects that network on
boot
You need to restart the device if WiFi network is unavailable on
device boot (or go to AT launcher)

19. Development - GPIO pins
private fun turnOnDiodeVoltage() {
val peripheralService = PeripheralManagerService()
try {
val mLedGpio = peripheralService.openGpio("BCM18")
mLedGpio?.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW)
mLedGpio?.value = true
} catch (e: IOException) {
Log.e("THINGS", "Error on PeripheralIO", e)
}
}

20. Development - Firebase sign-in
mAuth = FirebaseAuth.getInstance()
mAuth?.signInWithEmailAndPassword( "smart@home.pl" , "abchome")
?.addOnCompleteListener( this) { task ->
if (task.isSuccessful) {
val database = FirebaseDatabase.getInstance()
val diodeDBFieldRef = database.getReference( "diode")
} else {
Log.w( "THINGS", "signInWithEmail:failure" , task.exception)
}
}

21. Development - Firebase events
diodeRef.addValueEventListener( object : ValueEventListener {
override fun onDataChange(dataSnapshot: DataSnapshot) {
val isDiodeTurnedOn = dataSnapshot.getValue(Boolean:: class.java)
}
override fun onCancelled(error: DatabaseError) {
Log.w("THINGS!", "Failed to read value." , error.toException())
}
})

22. Development

23. Peripherals
- Buttons
- Motors
- Display
- Keyboards
- Matrix keyboards
- Diodes
- Switches
- Other DOM
Android Things IoT examples on GitHub - link

24. Peripherals - matrix keypad
CONTRIB DRIVERS - matrixkeypad
sample
public class BoardDefaults {
private static final String DEVICE_RPI3 = "rpi3";
public static String[] getRowPins() {
return new String[]
{"BCM27", "BCM5", "BCM6", "BCM26"};
}
public static String[] getColPins() {
return new String[] {"BCM16", "BCM24", "BCM23"};
}
}

25. public class MatrixKeypadActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
mMatrixKeypadDriver = new MatrixKeypadInputDriver(
BoardDefaults.getRowPins(),
BoardDefaults.getColPins(),
new int[] {KeyEvent.KEYCODE_NUMPAD_1, KeyEvent.KEYCODE_NUMPAD_2,
KeyEvent.KEYCODE_NUMPAD_3, KeyEvent.KEYCODE_NUMPAD_4,
KeyEvent.KEYCODE_NUMPAD_5, KeyEvent.KEYCODE_NUMPAD_6,
KeyEvent.KEYCODE_NUMPAD_7, KeyEvent.KEYCODE_NUMPAD_8,
KeyEvent.KEYCODE_NUMPAD_9, KeyEvent.KEYCODE_NUMPAD_MULTIPLY,
KeyEvent.KEYCODE_NUMPAD_0, KeyEvent.KEYCODE_NUMPAD_ENTER});
mMatrixKeypadDriver.register();
}
@Override public boolean onKeyDown(int keyCode, KeyEvent event) { ... }
@Override public boolean onKeyUp(int keyCode, KeyEvent event) { ... }
@Override protected void onDestroy() {
mMatrixKeypadDriver.close();
}
}

26. Drivers
- Contrib drivers open source (link)
- GPS drivers
- Human Input Device (HID) drivers
- Sensor drivers
- Custom drivers written in C/C++

27. UserDriverManager class
- Is responsible for registering/unregistering new user devices
- Available methods:
- registerGpsDriver(GpsDriver)
- registerInputDriver(InputDriver)
- registerSensorDriver(UserDriver)
- unregisterGpsDriver() //without arguments, because there can be only one
GPSDriver
- unregisterInputDriver(InputDriver) //there can be multiple InputDrivers
- unregisterSensorDriver(UserSensor) //there can be multiple UserSensors
- Unregister method should be called in onDestroy() method

28. How new device registration works?

29. How new device registration works?

30. GPS drivers
- External GPS device connected to an Android Things device
through a UART connection
- Support for GPS modules which return location data in the NMEA
format
- NMEA GPRMC (Recomennded Minimum Navigation) structure:
$GPRMC, <Time>,<Status>,<Latitude>,<Longitude>,<Speed>,<Angle>,<Date>,
<Variation>,<Integrity>,<Checksum>
- GPS support is possible with using GpsDriver class, included into
Android Things SDK

31. GPS drivers

32. Human Input Device (HID) drivers
- Support for peripherals like buttons, controller joysticks and
keyboards
- Peripherals can be connected to the board via UART, GPIO, I2C,
etc.
- InputDriver class allows to tie own human interactions to the
standard Android input

33. Human Input Device (HID) drivers

34. Sensors drivers
- Support for multiple types of sensors, like accelerometer,
gyroscope, magnetic field, etc.
- UserSensorDriver class contains methods for handling low power
and sleep mode
- Support for custom sensors types which are not already supported
in Android (wind speed, water pH levels, motion detection, etc.)

35. Sensors drivers

36. Sensors drivers

37. Sensors drivers - custom device types

38. Sensors drivers - unregister device
- Each new created sensor should be unregister in onDestroy()
method

39. Custom C/C++ drivers
- The native PIO APIs let you write C/C++ code to control GPIO,
PWM, I2C, SPI, UART peripherals
- Native drivers can be used in a Java code
- The Native PIO API contains the same classes as Standard
Android Things API
- Android Things application can be write purely in C/C++

40. Custom C/C++ drivers - getting started
- Firstable, clone the Android Things Native repo (link)
- Move cloned files to the native module in your project
- Edit CMakeLists.txt file and add the following lines:
- Add the following arch to the native module build.gradle

41. Custom C/C++ drivers - example

42. Custom C/C++ drivers - example

43. OpenWeave protocol
- standard for device communication
- built by Nest/Google
- connect devices via QR codes
- weave automatically takes care
of updates
- offline connection between devices
& secure cloud connection
- C++ core, Local & Cloud API
- low adoption level

44. Weave protocol
- open source:
https://github.com/openweave/openweave-core

45. Links
- Android Things - link, supported hardware - link
- Weave protocol - link, nest weave - link, source - link
- Developer console - link, releases (currently preview - 6.1)
- Raspberry Pi AT docs - link
- Android Things Native - link
- Android Things Native examples - link