Low-level Peripheral I/O with Android Things

Learn about Android Things and how to apply low-level peripheral I/O such as I2C and SPI.

Transcript

1. Low-level Peripheral I/O
2. Dennis Geurts Twitter: @dennisgggg Luminis, the Netherlands Dutch Android User Group The Things Network Arnhem
4. From Prototype to Production
5. Android SDK Android Studio Play Services Firebase Cloud Platform
6. !! It’s just your good old Android development !!
7. IoT Developer Console Automatic Security Updates Signed Images Verified Boot
8. SoM Architecture Google Managed BSP
9. Available
10. Mostly Pin-compatible
11. Android Things for Developers
14. Displays are Optional Consider Alternate UI
15. The Power of Android Automatic and Secure Managed by Google
16. How does it interact with the rest of the world?
17. GPIO PWM I2C SPI UART Peripheral I/O
18. GPIO PWM I2C SPI UART Input Sensors GPS Peripheral I/O User Drivers
19. GPIO PWM I2C SPI UART Input Sensors GPS Peripheral Driver Library Peripheral I/O User Drivers
20. Digital I/O (GPIO)
21. Digital I/O
22. // Open a peripheral connection PeripheralManagerService service = new PeripheralManagerService(); Gpio button = service.openGpio(GPIO_PIN_NAME); // Configure the peripheral button.setDirection(Gpio.DIRECTION_IN); button.setEdgeTriggerType(Gpio.EDGE_FALLING); // Attach callback for input events button.registerGpioCallback(new GpioCallback() { @Override public boolean onGpioEdge(Gpio gpio) { Log.i(TAG, "GPIO changed"); // Return true to continue listening to events return true; } }); Simple Peripheral I/O
23. private GpioCallback callback = new GpioCallback() { @Override public boolean onGpioEdge(Gpio gpio) { int keyAction = gpio.getValue() ? KeyEvent.ACTION_DOWN : KeyEvent.ACTION_UP; inputDriver.emit(new KeyEvent[]{ new KeyEvent(keyAction, KeyEvent.KEYCODE_SPACE)}); return true; } }; Button User Driver InputDriver inputDriver = InputDriver.builder(InputDevice.SOURCE_CLASS_BUTTON) .setName(DRIVER_NAME) .setVersion(DRIVER_VERSION) .setKeys(new int[]{KeyEvent.KEYCODE_SPACE}) .build(); UserDriverManager.getManager().registerInputDriver(inputDriver);
24. dependencies { compile 'com.google.android.things.contrib:driver-button:...' } ButtonInputDriver inputDriver = new ButtonInputDriver( GPIO_PIN_NAME, Button.LogicState.PRESSED_WHEN_LOW, KeyEvent.KEYCODE_SPACE); inputDriver.register(); Button Library Driver “Hey, there’s a driver for that !”
25. contrib-drivers “Hey, there’s a driver for that !” https://github.com/androidthings/contrib-drivers
26. Digital I/O - PWM
27. Digital I/O - PWM • Provide average voltage between min - max • Control servo • Control buzzer • Dim light intensity
28. Digital I/O - PWM
29. Digital I/O - PWM
30. Digital I/O - PWM
31. Digital I/O - PWM
32. Digital I/O - PWM - contrib drivers “Hey, there’s a driver for that !”
33. Higher-end protocols • UART • Inter-Integrated Circuit (I2C) • Serial Peripheral Interface (SPI) • Inter-IC Sound (I2S)
34. Higher-end protocols • Inter-Integrated Circuit (I2C) • Serial Peripheral Interface (SPI)
35. Two wire - I2C
36. Two wire - I2C • Synchronous • Master - Slave • Master provides the clock - multiple masters possible • 2- wires (3 with ground) • Devices have addresses
37. Two wire - I2C Low-level protocol
38. Two wire - I2C Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Register 0xC1 Datasheets Register 0xA0
39. Two wire - I2C PeripheralManager to access the I2C bus
40. Two wire - I2C PeripheralManager to access the I2C bus
41. Two wire - I2C • First read current register value • Then write to register (flipping a bit)
42. Two wire - I2C • Or just read from the given register
43. Two wire - I2C • Or just write raw data
44. Two wire - I2C - contrib-drivers “Hey, there’s a driver for that !”
45. Two wire - I2C - contrib-drivers “Hey, there’s a driver for that !”
46. SPI
47. SPI • Synchronous/ Master - Slave/ Master provides clock • 3 wires (4 with ground) • +1 wire for each device / to select it • High-speed 2Mbps
48. SPI Daisy chain - e.g. shift registers
49. SPI Low-level protocol
50. SPI Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Datasheets Register 0xC2 Datasheets Register 0xA0
51. SPI PeripheralManager to access the SPI bus
52. SPI PeripheralManager to access the SPI bus
53. SPI Half-duplex transfer of data
54. SPI Full-duplex transfer of data
55. SPI - contrib-drivers “Hey, there’s a driver for that !”
56. SPI - contrib-drivers “Hey, there’s a driver for that !”
57. Conclusion • Android ecosystem • OTA updates • Security • Ease of development - Android Studio • Driver ecosystem for peripherals • Feel free to build your own - they accept contributions (Currently working on) • RFM95 (LoRa / LoRaWAN - 868 MHz) • NRF24L01+ (2.4 GHz radio) • 433 MHz (low-level OOK)
58. DEMO TIME !! • PWM LED / BUZZER • RFM95 • NRF24L01