Droidcon London - Hardware Development With KMP and Compose Multiplatform

Transcript

1. Enrique Ramirez Hardware Development With KMP and Compose Multiplatform
2. Guitar pedal effect A.K.A. Stomp box
4. guitarInputStream .map(::compressor) .map(::phaser) .map(::overdrive) .map(::equaliser) .map(::delay)
6. Sound A Sound B
7. Switcher Sound A Sound B Sound C Sound D Computer Sound A Sound B
8. Matrix8 Requirements • Switch multiple guitar pedals and its order instantly • Display which pedals are selected and switched on • Wireless communication for a companion app
9. Switcher Crosspoint Matrix Y1 Y2 Y3 X1 X2 X3 3 2 1
10. ADG2188 The Switcher • I²C communication • 8 inputs x 8 outputs ?
12. PCB
 Manufacturing
 Service
13. ADG2188 Result switcher board
14. I/O Boards • Mono audio I/O board • JST connectors • 6.35mm, 1/4’’ jack connectors
15. 3D Printing • Helps keep your prototype tidy. • Help you visualise your project as a whole. • Helps fi nding issues and iterating on them. • You can use online services. • It has a learning curve.
17. How do we build this?
18. We are Mobile Software Engineers not Embedded
20. Transferable Skills
21. Which Platform?
22. Original versions Android Things implementation
25. The Raspberry PI A Swiss Army knife • Small form factor computer • Con fi gurable I/O • Integrated wireless comms * • OS Customisation • Good Community support • Display capabilities • Open Source friendly • Wide range of variants
26. KMP O ffi cial documentation Embedded
27. Compose Multiplatform KMP Application JVM Desktop Target SKIKO SKIA Compose for Desktop
29. Architecture Presentation UI UseCases Switcher State Matrix8ViewModel Matrix8Screen GetMatrix8UseCase
 SwitchPedalUseCase
30. Talking to the Hardware
31. Circuit level I/O I²C Pins
32. I²C Pedals Guitar/Amp Display
33. Pi4J Project I/O Java Library for the Pi • Compatible with multiple boards • Very fl exible • Support for I²C, SPI, GPIO, UART, PWM • Kotlin DSL
34. I²C Inter-Integrated Circuit • 2 wires required for multiple devices in the bus • 7 bit addressing, up to 128 target devices • Bidirectional communication • Multiple speed modes: 100kbps, 400kbps, 1Mbps, 1.7Mbps, 3.4Mbps, 5Mbps
35. I²C Bus Main MCU Target Device 1 SDA SCL Target Device 2 Target Device N
36. I²C Communication Commands
37. Example ON/OFF | AX3 | AX2 | AX1 | AX0 | AY2 | AY1 | AY0 8Bit Word ON X2 -> Y4 1 0 0 1 0 1 0 0 ON 2 4
38. override suspend fun sendData(commandValue: List<Byte>) { pi4j { i2c(1, ADG2188_DEVICE_ADDRESS) {
 id("ADG2188")
 linuxFsI2CProvider() }.use {
 commandValue.forEach {
 adg2188.write(it)
 }
 } }
 }
 

39. private data class AddressByte(
 val enabled: Boolean,
 val x: Int,
 val y: Int ) {
 fun toByte(): Byte {
 val enableBit = if (enabled) 1 else 0
 return (((enableBit shl 7) or (x.xAddressOffset() shl 3)) or y).toByte()
 }
 
 private fun Int.xAddressOffset(): Int {
 return if (this < 6) return this else (this + 2)
 }
 }

40. X (Input ports) Y (Output ports) Sound A
41. Current State Di ff State Δ New state Di ff State Δ List of I2c commands
42. private fun getMatrix(pedals: List<Pedal>): Array<BooleanArray> { val enabledPedals = pedals.filter { it.enabled } val matrix = Array(8) { BooleanArray(8) } if (enabledPedals.isEmpty()) { matrix[0][0] = true return matrix } enabledPedals.forEachIndexed { index, pedal -> when (index) { 0 -> { matrix[0][pedal.ioChannel] = true // If only 1 pedal in the list, output index should be 0 (output) val outputIndex = enabledPedals.getOrNull(1)?.ioChannel ?: 0 matrix[pedal.ioChannel][outputIndex] = true } enabledPedals.lastIndex -> matrix[pedal.ioChannel][0] = true else -> matrix[pedal.ioChannel][enabledPedals[index + 1].ioChannel] = true } } return matrix }
43. private fun getAddressByteList( oldMatrix: Array<BooleanArray>, newMatrix: Array<BooleanArray> ): List<AddressByte> { val addressesPairList = mutableListOf<AddressByte>() for (x in oldMatrix.indices) { for (y in oldMatrix[x].indices) { if (oldMatrix[x][y] != newMatrix[x][y]) { addressesPairList.add( AddressByte( enabled = newMatrix[x][y], x = x, y = y, ) ) } } } return addressesPairList.toList() }
44. Architecture Presentation UI UseCases I²C Gateway Switcher State Matrix8ViewModel Matrix8Screen GetMatrix8UseCase
 SwitchPedalUseCase ADG2188 Driver
45. V1 Raspberry Pi 3
46. Adding the buttons and LEDs
47. GPIO General Purpose Input/Output • Dedicated logic pins • Con fi gurable to read or write. • Ideal for simple applications. (Button read, LED switching, …)
48. Raspberry Pi I/O Used Free to use
49. GPIO Button Reading
50. companion object { private const val DIGITAL_INPUT_PIN_SOUND_A: Int = 7 // GPIO 4 private const val DIGITAL_INPUT_PIN_SOUND_B: Int = 29 // GPIO 5 } fun setButtonListener(onButtonPressed: (matrixButton: MatrixButton) -> Unit) { pi4j { matrix8Button(DIGITAL_INPUT_PIN_SOUND_A) { onButtonPressed(MatrixButton.SOUND_A) } matrix8Button(DIGITAL_INPUT_PIN_SOUND_B) { onButtonPressed(MatrixButton.SOUND_B) } } } private fun Context.matrix8Button( pin: Int onButtonPressed: () -> Unit, ) { digitalInput(pin) { pull(PullResistance.PULL_DOWN) debounce(1000L) piGpioProvider() }.onHigh { onButtonPressed() } }
51. GPIO Light up LED
52. companion object { private const val DIGITAL_OUTPUT_PIN_SOUND_A: Int = 26 // GPIO 6 private const val DIGITAL_OUTPUT_PIN_SOUND_B: Int = 31 // GPIO 7 } fun setLED(button: MatrixButton, on: Boolean) { pi4j { val pin = when (button) { MatrixButton.SOUND_A -> DIGITAL_OUTPUT_PIN_SOUND_A MatrixButton.SOUND_B -> DIGITAL_OUTPUT_PIN_SOUND_B } val digitalState = if(on) DigitalState.HIGH else DigitalState.LOW digitalOutput(pin) { initial(digitalState) shutdown(digitalState) piGpioProvider() } } }
53. Architecture Presentation UI UseCases I²C Gateway Switcher State Matrix8ViewModel Matrix8Screen GetMatrix8UseCase
 SwitchPedalUseCase ADG2188 Driver GPIO Gateway LEDs, FootSwitch
54. V2 Raspberry PI Zero 2
55. Companion app communication
56. Companion app communication Options • TCP/IP based • Wi fi Direct • HTTP Server • Websockets Server • MQTT • Bluetooth • Bluetooth Classic • Bluetooth low energy
57. BLE Communication Advertise BLE Service Read Publish Characteristic Scan Connect Handle connections Read Write Subscribe ID ID
58. BLE Java Library • Simple interface • Service and characteristic creation capabilities • Not maintained (last change 6 years ago) • Easy to modify to extend capabilities • No maven repository (Requires checkout and jar generation) https://github.com/tongo/ble-java V1
59. BLE Kotlin Library • Simple interface • Kotlin DSL • Hosted in Maven Central • Linux Bluetooth Stack only (Multiplatform in Future) https://github.com/kikermo/ble-server BLE-SERVER V2
60. BLE Stack On Raspberry PI D-BUS BLUEZ Bluetooth Core (Low level) BLE Application
61. bleServer { serverName = DEVICE_NAME bluezServerConnector() primaryService { uuid = UUID.fromString(SERVICE_UUID) name = SERVICE_NAME characteristic { uuid = UUID.fromString(CHARACTERISTIC_UUID_PRESETS) name = CHARACTERISTIC_NAME_PRESETS writeAccess = AccessType.Write { presetByteArray -> val presetIndex = presetByteArray.first().toInt() // 00-A, 01-B, 02-C, 03-D, XX-A presetStateFlow.value = initialPresets.getOrNull(presetIndex) ?: initialPresets.first() } readAccess = AccessType.Read notifyAccess = AccessType.Notify valueChangingAction { action -> CoroutineScope(Dispatchers.IO).launch { presetStateFlow.collectLatest { action(it.toCharacteristicValue()) } } } } } }
62. characteristic { uuid = UUID.fromString(CHARACTERISTIC_UUID_PEDALS) name = CHARACTERISTIC_NAME_PEDALS writeAccess = AccessType.Write { pedalsByteArray -> println("Bytes ${pedalsByteArray.joinToString { it.toString() }}") presetStateFlow.value = presetStateFlow.value.copy(pedals = pedalsByteArray.toPedalList()) } readAccess = AccessType.Read notifyAccess = AccessType.Notify valueChangingAction { action -> CoroutineScope(Dispatchers.IO).launch { presetStateFlow.map { it.pedals }.collectLatest { action(getCharacteristicValue(it)) } } } }
63. Architecture Presentation UI UseCases I²C Gateway BLE Service Switcher State Matrix8ViewModel Matrix8Screen GetMatrix8UseCase
 SwitchPedalUseCase Matrix8 State Characteristic ADG2188 Driver GPIO Gateway LEDs, FootSwitch
64. DEMO TIME
65. Matrix8 WIP
66. Wi-fi Direct AKA Wi fi P2P • Useful for device setup • No need of network to operate • Android friendly • No direct way to setup via Kotlin 😢
67. Http Server Ktor • Kotlin library • O ffi cially supported • Multiple engines to choose from: Jetty, Netty, Tomcat, CIO, ServletApplicationEngine • WebSocket capabilities
68. fun Application.configureRouting() { routing { staticResources("static", "static") route("/matrix8") { get(“/pedals”) { call.respond(pedals) } post("/pedals") { try { val pedals = call.receive<List<Pedal>>() setPedals(pedals) call.respond(HttpStatusCode.NoContent) } catch (ex: IllegalStateException) { call.respond(HttpStatusCode.BadRequest) } catch (ex: JsonConvertException) { call.respond(HttpStatusCode.BadRequest) } } } } }
69. Future of Matrix8 • KMP Companion app (desktop/mobile) • Edit mode • MIDI port • Use the audio input of the Pi (e.g. Guitar Tuner) • CI/CD with distributable updates
70. THANKS Resources