Flutter Flutter 💙 Embedded 1

박제창 @Dreamwalker Flutter Seoul GDG Golang Korea Intro @Dreamwalker 2

GDG Golang Korea https://festa.io/events/3890 3

“What is an embedded system for you?” 4 Intro

5 Intro

6 Source https://en.wikipedia.org/wiki/Apple_M2 https://ko.wikipedia.org/wiki/%EC%9D%B8%ED%85%94_%EC%BD%94%EC%96%B4_i7 Intro

7 Source https://en.wikipedia.org/wiki/ATmega328 https://hackaday.com/tag/bcm2711/ Intro

8 Source https://en.wikipedia.org/wiki/ATmega328 https://hackaday.com/tag/bcm2711/ Intro https://en.wikipedia.org/wiki/Microcontroller

9 Intro Source: https://store-usa.arduino.cc/products/arduino-uno-rev3?selectedStore=us

10 Intro Source: https://store-usa.arduino.cc/pages/uno-r4?selectedStore=us

11 Intro https://www.renesas.com/us/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus/ra4m1-32-bit -microcontrollers-48mhz-arm-cortex-m4-and-lcd-controller-and-cap-touch-hmi Renesas RA4M1 https://docs.arduino.cc/resources/schematics/ABX00087-schematics.pdf?_gl=1*17zto*_ga*MzgzNzkzMjMyLjE2OTIwODA1OTk.*_ga_NEXN8H46L5*MTY5MjA4MDU5OC 4xLjEuMTY5MjA4Mjk5NC4wLjAuMA..

12 Intro Source: https://www.renesas.com/us/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus/ra4m1-32-bit-microcontrollers-48mhz-arm-cortex-m4-and-lcd-contr oller-and-cap-touch-hmi Renesas RA4M1 (Arm® Cortex®-M4) 32-bit Microcontrollers with 48MHz Arm® Cortex®-M4 and LCD Controller and Cap Touch for HMI

13 Intro Source: https://www.renesas.com/us/en/products/microcontrollers-microprocessors/ra-cortex-m-mcus/ra4m1-32-bit -microcontrollers-48mhz-arm-cortex-m4-and-lcd-controller-and-cap-touch-hmi

14 Intro Source: http://www.cocn.jp/material/ec9a4f2565e27e752d082827591d868e213ba413.pdf

15 Intro Source: https://www.raspberrypi.com/products/raspberry-pi-4-model-b/specifications/ Broadcom BCM2711, Quad core Cortex-A72 (ARM v8) 64-bit SoC @ 1.8GHz

16 Intro Source: https://coral.ai/products/som https://coral.ai/products/dev-board CPU NXP i.MX 8M SoC (quad Cortex-A53, Cortex-M4F) GPU Integrated GC7000 Lite Graphics ML accelerator Google Edge TPU coprocessor: 4 TOPS (int8); 2 TOPS per watt System-on-Module (SoM)

17 Intro Source: https://www.nvidia.com/en-us/autonomous-machines/embedded-systems/

“What's the difference?? 󰤇” 18 Intro

19 Intro Clock 16 MHz & 48MHz vs > 1.8 GHz

20 Intro Source: https://forums.raspberrypi.com/viewtopic.php?t=271632

21 Intro Source: https://www.analog.com/en/analog-dialogue/articles/understanding-and-using-the-no-os-and-platform-drivers.html

“Flutter Embedded?? 󰤇” 22 Intro

23 Intro

24 Intro Source https://en.wikipedia.org/wiki/Sony https://medium.com/flutter/whats-new-in-flutter-2-2-fd00c65e2039

About Raspberry Pi Section 01 25

26 Section 01 ● 설립: 2009년 5월 ● 창립자: David Braben, Jack Lang, Alan Mycroft, Robert Mullins, Eben Upton ● 활동: The object of the charity is to further the advancement of education of adults and children, particularly in the field of Computers, Computer Science and related subjects Raspberry Pi Foundation

27 Section 01 Raspberry Pi Foundation 2009년 2016 2018 Raspberry Pi Ltd Raspberry Pi Foundation Headquarters 출처: https://en.wikipedia.org/wiki/Raspberry_Pi_Foundation#/media/File:RpiFoundationHeadquarters.jpg

28 Section 01 Raspberry Pi Foundation ● Eben owned a BBC Micro as a kid, and as an adult he set about designing Raspberry Pi to do what the BBC Micro had done for him: inspire widespread interest in computer programming. ● As a Director of Studies, he noticed a decline in the number of students applying to study computer science, and had an idea: he thought that if he could get affordable hardware into the hands of young people at the right point, it could spark an interest in taking computing further. https://www.raspberrypi.com/news/the-bbc-micro-and-raspberry-pi/ https://spectrum.ieee.org/eben-upton-on-the-raspberry-pis-industrial-crossover-and-why-there-will-never-be-a-pi-9

29 Section 01 BBC Micro 1 December 1981

30 Section 01 BBC Micro 1 December 1981

31 Section 01 BBC Micro https://artsandculture.google.com/asset/bbc-micro-model-b-acorn-computer-company/PgFx5X_lPpjhOg https://oldcomputers.net/bbc-micro.html ● CPU: 2 MHz MOS Technology 6502/6512 ● Memory: 16–128KiB ● Storage: 100–800 KB

32 Section 01 BBC Micro:Bit https://en.wikipedia.org/wiki/Micro_Bit ● Release date ○ v1: 10 February 2016 ○ v2: 13 October 2020 ● CPU ○ v1: Nordic nRF51822, 16 MHz ARM Cortex-M0 core, 256 KB Flash, 16 KB RAM ○ v2: Nordic nRF52833, 64 MHz ARM Cortex-M4 core, 512 KB Flash, 128 KB RAM

33 Section 01 ● 수익: £112,663,267 (192,266,445,008원) ● 지출: £101,823,872 (173,768,384,387원) ● 31 December 2021 기준 Raspberry Pi Foundation 출처 https://register-of-charities.charitycommission.gov.uk/charity-search/-/charity-details/5002372

Section 01 출처 https://www.raspberrypi.com/news/logo-competition/ 34

Section 01 출처 https://www.raspberrypi.com/news/logo-competition-we-have-a-winner/ https://en.wikipedia.org/wiki/Buckminsterfullerene ● Created by Paul Beech ● Buckminsterfullerene(=풀레렌) ○ 32 Face ○ 11 are visible in the logo ● The Raspberry Pi has ○ a 32-bit processor and an ARM11 on board 35

36 Section 01 Raspberry Pi - 1 (2012) https://www.sparkfun.com/products/retired/11546 https://en.wikipedia.org/wiki/Raspberry_Pi ● CPU: Broadcom BCM2835 SoC ○ 700 MHz ARM1176JZF-S core CPU ● GPU: Broadcom VideoCore IV GPU ● 512 MB RAM ● 2 x USB2.0 Ports ● Storage: SD/MMC/SDIO ● GPIO 26 ● Full HD 1080p

37 Section 01 Raspberry Pi - 2 (2015) https://en.wikipedia.org/wiki/Raspberry_Pi ● CPU: Broadcom BCM2836 / 7 SoC ○ 900MHz quad-core ARM Cortex-A7 CPU (32bit) ○ 900 MHz ARM Cortex-A53 (64bit) ● GPU: VideoCore IV MP2 250 MHz ● 1GB LPDDR2 RAM ● 40 GPIO ● Full HD 1080p ● 4 x USB2.0 Ports ●

38 Section 01 Raspberry Pi - 3 (2018) https://en.wikipedia.org/wiki/Raspberry_Pi ● CPU: Broadcom BCM2837B0 SoC ○ 1.5GHz ARM Cortex-A53 (64 bit) ● GPU: VideoCore IV MP2 250 MHz ● 1GB LPDDR2 RAM ● 40 GPIO ● 2 x USB2.0 Ports ● Full HD 1080p ● Wi-Fi, BLE 4.x

39 Section 01 Raspberry Pi - 4 (2019) https://en.wikipedia.org/wiki/Raspberry_Pi ● CPU: Broadcom BCM2711 SoC ○ 1.5GHz ARM Cortex-A72 (64 bit) ● GPU: VideoCore IV MP2 500 MHz ● RAM: 1, 2, 4, 8GB LPDDR4-3200 SDRAM ● 40 GPIO ● 2 x USB2.0 Ports ● 2 x USB3.0 Ports ● Wi-Fi, BLE 5 ● Dual displays 4K output ● 2 x Micro HDMI

40 Section 01 Raspberry Pi Zero, Compute https://en.wikipedia.org/wiki/Raspberry_Pi

41 Section 01 Raspberry Pi Cluster https://www.raspberrypi.com/tutorials/cluster-raspberry-pi-tutorial/

42 Section 01 Raspberry Pi OS Raspbian is a free operating system based on Debian optimized for the Raspberry Pi hardware. Raspbian → Raspberry Pi OS

43 Section 01 Raspberry Pi OS 2023-05-03: * 64-bit Mathematica added to rp-prefapps * Bug fix - occasional segfault in CPU temperature plugin * Bug fix - X server crash when changing screen orientation * Bug fix - X server DPMS not working * Mathematica updated to 13.2.1 * Matlab updated to 23.1.0 * Chromium updated to 113.0.5672.59 * Raspberry Pi Imager updated to 1.7.4 * RealVNC server updated to 7.0.1.49073 * RealVNC viewer updated to 7.0.1.48981 * Updated VLC HW acceleration patch * libcamera - Add generalised statistics handling. - Fix overflow that would cause incorrect calculations in the AGC algorithm. - Improve IMX296 sensor tuning. * libcamera-apps - Improve handling of audio resampling and encoding using libav - Improve performance of QT preview window rendering - Add support for 16-bit Bayer in the DNG writer - Fix for encoder lockup when framerate is set to 0 - Improved thumbnail rendering * picamera2 - MJPEG server example that uses the hardware MJPEG encoder. - Example showing preview from two cameras in a single Qt app. - H264 encoder accepts frame time interval for SPS headers. - H264 encoder should advertise correct profile/level. - H264 encoder supports constant quality parameter. - Exif DateTime and DateTimeOriginal tags are now added. - Various bug fixes (check Picamera2 release notes for more details). * Some translations added * Raspberry Pi firmware 055e044d5359ded1aacc5a17a8e35365373d0b8b * Linux kernel 6.1.21 https://downloads.raspberrypi.org/raspios_arm64/release_notes.txt

44 Section 01 Raspberry Pi GPIO https://www.raspberrypi.com/documentation/computers/raspberry-pi.html

45 Section 01 Raspberry Pi GPIO ● https://pinout.xyz/ ● Pin Map을 모두 외우기 어려운 분들을 위한 … ● 출력을 해서 보거나 웹에서 간편하게 검색

46 Section 01 Raspberry Pi 1. 가격 2. 리눅스 베이스 OS 설치 가능 3. SD 카드 속도 및 그 외 이슈

Raspberry Pi Prepare & Setup Section 02 47

48 Section 02 준비하기 https://www.raspberrypi.com/software/raspberry-pi-desktop/ ● 저렴한 컴퓨터라고 했지만 컴퓨터 처럼 구성하려면 어떤것들이 필요할까요? ● 어느 정도 개발이 가능한 환경으로 구성하기

49 준비하기 ● 저렴한 컴퓨터라고 했지만 컴퓨터 처럼 구성하려면 어떤것들이 필요할까요? 1. RPi 2. 마우스 3. 키보드 4. Monitors & Display 5. HDMI Cable 6. SD Card 7. SD Card Reader 8. 방열판 & 팬 9. (옵션) 케이스 10. 전원 어댑터 11. 이더넷 케이블 12. 스피커 Section 02

50 준비하기 DSI LCD Display Section 02 https://www.raspberrypi.com/documentation/accessories/display.html Display Serial Interface

51 준비하기 Camera - CSI Camera Serial Interface Section 02 https://projects.raspberrypi.org/en/projects/getting-started-with-picamera

52 준비하기 Camera USB Section 02 https://www.logitech.com/ko-kr/products/webcams/c270-hd-webcam.960-000626.html

“아…Model 3까지가 이 정도에요” 53 Section 02

54 준비하기 - Model 4 1. RPi - 기본 구매 2. 마우스 - 구매 3. 키보드 - 구매 4. Monitors & Display - 구매 5. HDMI Cable - 구매 6. SD Card - 구매 7. SD Card Reader - 구매 8. 방열판 & 팬 - 구매 9. (옵션) 케이스 - 구매 10. 전원 어댑터 - 구매 11. 이더넷 케이블 - 구매 12. 스피커 - 구매 추가 구매 13. HDMI - HDMI Micro Adapter & 케이블 14. 전원 Adapter Usb - C 15. Micro-B to C 💸 Section 02

55 준비하기 https://www.raspberrypi.com/products/ ● Model 4 Section 02

56 준비하기 https://www.waveshare.com/game-hat.htm ● 3.5inch IPS screen, 480 × 320 resolution. ● 60 frame experience, smooth display, no more frame loss. ● Compatible with Raspberry Pi A+/B+/2B/3B/3B+/4B (Raspberry Pi Zero/Zero W/Zero WH requires another HDMI cable). ● Integrates battery charge circuitry, powered from a 18650 lithium battery (NOT included), plays anywhere anytime. ● Battery capacity indicator. ● Onboard speaker and earphone jack, listen to the familiar BGM from the old days. Section 02 I/O 23 Flutter, Dart, and Raspberry Pi

“저 준비 다 했어요 이제 뭐해야하죠? 󰤇” 57 Intro Section 02

58 Intro Section 02 1. 하드웨어 셋팅 및 결합하기 2. SD Card 초기화 3. OS 설치하기 → OS를 설치하기 위한 PC가 필요 4. 전원 인가 및 부팅 확인하기

59 Intro Section 02 1

60 Intro Section 02 1 2

61 Intro Section 02 1 2

62 Intro Section 02 1 2

63 Intro Section 02 I/O 23 Flutter, Dart, and Raspberry Pi 1 2 3

64 Intro Section 02 1

Install Flutter for embedded Section 03 65

66 Section 03 Install Flutter ● Raspberry Pi OS ⇒ Debian ⇒ Linux ● Operating Systems: Linux (64-bit) ● Disk Space: 600 MB (does not include disk space for IDE/tools). ● Tools: Flutter depends on these command-line tools being available in your environment.

67 Section 03 Install Flutter Tools: Flutter depends on these command-line tools being available in your environment. bash, curl, file, git 2.x, mkdir, rm, unzip, which, xz-utils, zip Shared libraries: Flutter test command depends on this library being available in your environment. libGLU.so.1 - provided by mesa packages such as libglu1-mesa on Ubuntu/Debian and mesa-libGLU on Fedora.

68 Section 03 Install Flutter

69 Section 03 Install Flutter

70 Section 03 Install Flutter

71 Section 03 UI Toolkit 1. GTK : GNOME 2. Qt 3. SDL : OSS 4. WebKit : Apple 5. Flutter : Google 6. Kotlin Multiplatform : Jet Brains 7. Unity 8. …

72 Section 03 Wayland DRM openGL ES GLS Kernel Mesa Window Manager

Rpi GPIO with Flutter Section 04 73

74 Section 04 Push Button Push Button Push Button Push Button Push Button Push Button Display 1 2

75 Section 04 BCM2711 https://datasheets.raspberrypi.com/ bcm2711/bcm2711-peripherals.pdf

76 Section 04 BCM2711 https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf ● There are 58 General-Purpose Input/Output (GPIO) lines split into three banks. ● Bank 0 contains GPIOs 0 to 27, bank 1 contains GPIOs 28 to 45, and bank 2 contains GPIOs 46 to 57. ● All GPIO pins have at least two alternative functions within BCM2711. ● The alternate functions are usually peripheral IO, and a single peripheral may appear in multiple banks to allow flexibility on the choice of IO voltage (as each bank has a selectable IO voltage).

77 Section 04 BCM2711 https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf

78 Section 04 BCM2711 https://datasheets.raspberrypi.com/bcm2711/bcm2711-peripherals.pdf

79 Section 04

Native API ffi build_native Rpi_gpio_ext .cc Native Flutter Flutter 80 Section 04 rpi_gpio

81 Section 04 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc rpi_gpio Rpi_gpio_ext.cc

rpi_gpio_ext.cc int64_t setupGpio() { int fd = open("/dev/gpiomem", O_RDWR | O_SYNC | O_CLOEXEC); if (fd < 0) return -1; void *gpio_map = mmap( 0, // Any adddress in our space will do BLOCK_SIZE, // Map length PROT_READ | PROT_WRITE, // Enable reading & writting to mapped memory MAP_SHARED, // Shared with other processes fd, // File to map 0x3F200000 // Offset to GPIO peripheral ); 82 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc

#if defined( RPI0 ) || defined( RPI1 ) #define GPIO_BASE 0x20200000UL #elif defined( RPI2 ) || defined( RPI3 ) #define GPIO_BASE 0x3F200000UL #elif defined( RPI4 ) #define GPIO_BASE 0xFE200000UL #else #error Unknown RPI Model! #endif 83

void setGpioMode(int bcmGpioPin, int mode) { int offset = bcmGpioPin / 10; int shift = (bcmGpioPin % 10) * 3; *(gpio + offset) = (*(gpio + offset) & ~(7 << shift)) | ((mode & 0x7) << shift); } 84 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc rpi_gpio_ext.cc

void setGpioInput(int64_t bcmGpioPin, int64_t pullUpDown) { setGpioMode(bcmGpioPin, FSEL_INPT); // 37 is GPIO up/down register, 38 and 39 are GPIO up/down set bits *(gpio + 37) = pullUpDown & 3; delayMicroseconds (5); *(gpio + (bcmGpioPin < 32 ? 38 : 39)) = 1 << (bcmGpioPin & 31); delayMicroseconds (5); *(gpio + 37) = 0; delayMicroseconds (5); *(gpio + (bcmGpioPin < 32 ? 38 : 39)) = 0; delayMicroseconds (5); } 85 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc rpi_gpio_ext.cc

// Read the input voltage on a GPIO pin and return either true (high) or false (low). int64_t readGpio(int64_t bcmGpioPin) { // 13 and 14 are GPIO input bits return (*(gpio + (bcmGpioPin < 32 ? 13 : 14)) & (1 << (bcmGpioPin & 31))); } // Set the output voltage on a GPIO pin to high (true, non-zero) or low (false, zero). void writeGpio(int64_t bcmGpioPin, int64_t newValue) { // 7 and 8 are set GPIO output HIGH bits, 10 and 11 are set GPIO output LOW bits. *(gpio + (newValue != 0 ? 7 : 10) + (bcmGpioPin < 32 ? 0 : 1)) = 1 << (bcmGpioPin & 31); } 86 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc rpi_gpio_ext.cc

Native API ffi build_native Rpi_gpio_ext .cc Native Flutter Flutter 87 Section 04 rpi_gpio

g++ -fPIC -c rpi_gpio_ext.cc # use --no-undefined to check for missing libraries gcc -shared -lpthread -Wl,-soname,librpi_gpio_ext.so -o librpi_gpio_ext.so rpi_gpio_ext.o # Copy the library cp librpi_gpio_ext.so ../librpi_gpio_ext.so 88 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/native/rpi_gpio_ext.cc build_native

void main(List args) { final nativeDir = Directory(join(pkgRootDir.path, 'lib', 'src', 'native')); final buildScriptFile = File(join(nativeDir.path, 'build_native')); assertRunningOnRaspberryPi(); final buildResult = Process.runSync(buildScriptFile.path, []); } 89 https://github.com/danrubel/rpi_gpio.dart/blob/main/bin/build_native.dart build_native.dart

Native API ffi build_native Rpi_gpio_ext .cc Native Dart Flutter 90 Section 04 rpi_gpio

ffi.DynamicLibrary findDynamicLibrary() { String libName; if (Platform.isLinux) { libName = 'librpi_gpio_ext.so'; } else { // Windows: Debug\rpi_gpio_ext.dll // MacOS: librpi_gpio_ext.dylib throw 'Unsupported OS: ${Platform.operatingSystem}'; } /// } 91 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/rpi_gpio_isolate.dart rpi_gpio_isolate.dart

class RpiGpioLibImpl implements RpiGpioLib { final int Function() _setupGpio; final int Function() _disposeGpio; final void Function(int, int) _setGpioInput; final int Function(int) _readGpio; final void Function(int) _setGpioOutput; final void Function(int, int) _writeGpio; 92 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/rpi_gpio_isolate.dart rpi_gpio_isolate.dart

RpiGpioLibImpl(ffi.DynamicLibrary dylib) : _setupGpio = dylib .lookup>('setupGpio') .asFunction(), _setGpioInput = dylib .lookup>('setGpioInput') .asFunction(), _readGpio = dylib .lookup>('readGpio') .asFunction(), 93 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/rpi_gpio_isolate.dart rpi_gpio_isolate.dart

void isolateMain(SendPort sendPort) { final gpioLib = RpiGpioLibImpl(findDynamicLibrary()); final cmdHandler = RpiGpioCmdHandler(sendPort, gpioLib); var receivePort = ReceivePort(); sendPort.send(comm.initCompleteRsp(receivePort.sendPort)); receivePort.listen((data) { comm.dispatchCmd(data, cmdHandler); }); } 94 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/rpi_gpio_isolate.dart rpi_gpio_isolate.dart

Future initialize_RpiGpio({ Completer? onError, }) => RpiGpio.init( onError: onError, isolateEntryPoint: isolateMain, ); 95 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/rpi_gpio.dart rpi_gpio.dart

class RpiGpio extends Gpio { static bool _instantiatedGpio = false; late SendPort _sendPort; late StreamSubscription _receivePortSubscription; late StreamSubscription _onErrorSubscription; final Completer? _onError; late _RpiGpioResponseHandler _rspHandler; 96 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/rpi_gpio.dart rpi_gpio.dart

abstract class Gpio { final _allocatedPins = []; Future dispose(); GpioInput input(int physicalPin, [Pull pull = Pull.off]); GpioOutput output(int physicalPin); /// } 97 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/gpio.dart gpio.dart

class _ChangedValueTransformer extends StreamTransformerBase { StreamController? _controller; T? lastValue; @override Stream bind(Stream stream) { late StreamSubscription subscription; _controller = StreamController(onListen: () { subscription = stream.listen((T newValue) { if (newValue != lastValue) { _controller!.add(newValue); lastValue = newValue; } });}, onCancel: () { subscription.cancel(); }); return _controller!.stream; } } 98 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/gpio.dart gpio.dart

Native API ffi build_native Rpi_gpio_ext .cc Native Dart Flutter 99 Section 04 rpi_gpio

static Future init({ Completer? onError, required Function(SendPort sendPort) isolateEntryPoint, SendPort? testSendPort, }) async { const timeout = Duration(seconds: 30); final rpiGpio = RpiGpio._(onError, i2c: i2c, spi: spi, eeprom: eeprom); await Isolate.spawn(isolateEntryPoint, receivePort.sendPort, onError: onErrorPort.sendPort); try { await rspHandler.initCompleter.future.timeout(timeout); } on TimeoutException { /// } catch (error) { /// } return rpiGpio .._receivePortSubscription = receivePortSubscription .._onErrorSubscription = onErrorSubscription .._rspHandler = rspHandler; } 100 https://github.com/danrubel/rpi_gpio.dart/blob/main/lib/src/rpi_gpio_impl.dart rpi_gpio_impl.dart

main() async { final gpio = await initialize_RpiGpio(); await run(gpio); } 101 main.dart

final button = gpio.input(11, Pull.up); bool lastValue = true; int count = 0; final completer = Completer(); final subscription = button.values .transform(Debouncer(lastValue, debounce)) .listen((bool newValue) { print('New button state: $newValue'); if (lastValue == false && newValue) { ++count; if (count == 3) { completer.complete(); } } led.value = lastValue = newValue; }); 102 app.dart

Section 04 103 Flutter, Dart, and Raspberry Pi Flutter Embedded https://youtu.be/jW3pqIpQtQE 2022-03-05

Section 04 104 Flutter, Dart, and Raspberry Pi Flutter Embedded https://youtu.be/jW3pqIpQtQE 2022-03-05

105 Summary 1. Embedded System에서 Flutter 사용 가능 a. Flutter 2.2부터 ARM64 Linux Host 지원 2. Raspberry Pi a. Rpi 4 b. Raspberry Pi OS ⇒ Debian 3. Rpi Flutter a. Flutter Linux로 설치 4. GPIO a. 레지스터 기반 b. Flutter gpio 활용 패키지도 존재 c. ffi 에 대한 이해와 사용

Thank You JaiChang Park he/him GDG Golang Korea / Flutter Seoul 106