Pi4J Spring Boot Starter

---

This project provides a Spring Boot Starter to use the Pi4J V2 library in your Spring Boot project.

About this project

• This starter requires Java 17 or higher.
• Multi-module project:
  • pi4j-spring-boot: auto-configure module
  • pi4j-spring-boot-starter: starter module
  • pi4j-spring-boot-starter-sample-app: example application to demonstrate and test the starter
• To run the sample app:
  • In IntelliJIDEA
  • Go to com.pi4j.spring.boot.sample.app.Application
  • Hit the run button
  • After the application has launched, open a browser and check:
    • http://localhost:8080/actuator/health
    • http://localhost:8080/actuator/info
  • Change the connected components:
    • LED on: http://localhost:8080/api/pi4j/led/true
    • LED off: http://localhost:8080/api/pi4j/led/false
    • Get the button state: http://localhost:8080/api/pi4j/button
    • Set text on the LCD: http://localhost:8080/api/pi4j/lcd/0/test

Running the sample application on a Raspberry Pi

• Start from Raspberry Pi OS or Pi4J CrowPi OS 0.2.0.
• Check the Java version, should be 17 or newer.

$ java -version
openjdk version "17.0.4" 2022-07-19
OpenJDK Runtime Environment (build 17.0.4+8-Debian-1deb11u1)
OpenJDK 64-Bit Server VM (build 17.0.4+8-Debian-1deb11u1, mixed mode, sharing)

• If Java is not installed yet, use SDKMAN.

$ sudo apt install zip
$ curl -s "https://get.sdkman.io" | bash 
# Open new terminal
$ sdk install java 17.0.7-zulu

• Get this project from GitHub and package it.

$ git clone https://github.com/Pi4J/pi4j-springboot.git
$ cd pi4j-springboot
$ chmod +x mvnw
$ ./mvnw package

• Run it as sudo to make sure Pi4J starts correctly.

$ sudo java -jar pi4j-spring-boot-starter-sample-app/target/pi4j-spring-boot-starter-sample-app-0.0.1.ea.jar 

# Or when installed with SDKMAN
$ sudo ~/.sdkman/candidates/java/17.0.7-zulu/bin/java -jar pi4j-spring-boot-starter-sample-app/target/pi4j-spring-boot-starter-sample-app-0.0.1.ea.jar

• Check the output of the application:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.2.5)

[pi4j-spring-boot-sample-app] [           main] c.p.spring.boot.sample.app.Application   : Starting Application using Java 22.0.2 with PID 62220 (/Users/frank/Documents/GitHub/pi4j-springboot/pi4j-spring-boot-starter-sample-app/target/classes started by frank in /Users/frank/Documents/GitHub/pi4j-springboot)
[pi4j-spring-boot-sample-app] [           main] c.p.spring.boot.sample.app.Application   : No active profile set, falling back to 1 default profile: "default"
[pi4j-spring-boot-sample-app] [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port 8080 (http)
[pi4j-spring-boot-sample-app] [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
[pi4j-spring-boot-sample-app] [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.20]
[pi4j-spring-boot-sample-app] [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
[pi4j-spring-boot-sample-app] [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 375 ms
[pi4j-spring-boot-sample-app] [           main] com.pi4j.Pi4J                            : New auto context
[pi4j-spring-boot-sample-app] [           main] com.pi4j.Pi4J                            : New context builder
[pi4j-spring-boot-sample-app] [           main] c.pi4j.boardinfo.util.BoardInfoHelper    : Detected OS: Name: Mac OS X, version: 15.0, architecture: aarch64
[pi4j-spring-boot-sample-app] [           main] c.pi4j.boardinfo.util.BoardInfoHelper    : Detected Java: Version: 22.0.2, runtime: 22.0.2+9, vendor: Azul Systems, Inc., vendor version: Zulu22.32+15-CA
...

• Open browser with http://{RASPBERRY_PI_IP_ADDRESS}:8080/actuator/info
• Output on a Raspberry Pi 4 (but truncated the pins-section):

  {
    "pi4j.status.led": "HIGH",
    "pi4j.status.button": "LOW",
    "os.name": "Linux",
    "os.architecture": "aarch64",
    "os.version": "6.6.31+rpt-rpi-2712",
    "board.name": "MODEL_5_B",
    "board.description": "Raspberry Pi 5 Model B",
    "board.model.label": "Model B",
    "board.cpu.label": "Cortex-A76",
    "board.soc": "BCM2712",
    "java.version": "17.0.11",
    "java.runtime": "17.0.11+9",
    "java.vendor": "Eclipse Adoptium",
    "java.vendor.version": "Temurin-17.0.11+9",
    "reading.volt.value": 0.72,
    "reading.temperature.celsius": 85.1,
    "reading.temperature.fahrenheit": 185.18,
    "reading.uptime": "18:26:04 up 33 min,  2 users,  load average: 2.31, 1.54, 1.09",
    "platform.current": "RaspberryPi Platform",
    "platform.raspberrypi.name": "RaspberryPi Platform",
    "platform.raspberrypi.description": "Pi4J Platform for the RaspberryPi series of products.",
    "provider.pigpio-spi.name": "PiGpio SPI Provider",
    "provider.pigpio-spi.description": "com.pi4j.plugin.pigpio.provider.spi.PiGpioSpiProviderImpl",
    "provider.pigpio-spi.type.name": "SPI",
    "provider.gpiod-digital-output.name": "GpioD Digital Output (GPIO) Provider",
    "provider.gpiod-digital-output.description": "com.pi4j.plugin.gpiod.provider.gpio.digital.GpioDDigitalOutputProviderImpl",
    "provider.gpiod-digital-output.type.name": "DIGITAL_OUTPUT",
    "provider.pigpio-serial.name": "PiGpio Serial Provider",
    "provider.pigpio-serial.description": "com.pi4j.plugin.pigpio.provider.serial.PiGpioSerialProviderImpl",
    "provider.pigpio-serial.type.name": "SERIAL",
    "provider.linuxfs-pwm.name": "LinuxFS PWM Provider",
    "provider.linuxfs-pwm.description": "com.pi4j.plugin.linuxfs.provider.pwm.LinuxFsPwmProviderImpl",
    "provider.linuxfs-pwm.type.name": "PWM",
    "provider.gpiod-digital-input.name": "GpioD Digital Input (GPIO) Provider",
    "provider.gpiod-digital-input.description": "com.pi4j.plugin.gpiod.provider.gpio.digital.GpioDDigitalInputProviderImpl",
    "provider.gpiod-digital-input.type.name": "DIGITAL_INPUT",
    "provider.linuxfs-i2c.name": "LinuxFS I2C Provider",
    "provider.linuxfs-i2c.description": "com.pi4j.plugin.linuxfs.provider.i2c.LinuxFsI2CProviderImpl",
    "provider.linuxfs-i2c.type.name": "I2C",
    "registry.button.name": "Press button",
    "registry.button.type.name": "DIGITAL_INPUT",
    "registry.button.description": "DIN-24",
    "registry.dout-22.name": "DOUT-22",
    "registry.dout-22.type.name": "DIGITAL_OUTPUT",
    "registry.dout-22.description": "DOUT-22",
    "registry.i2c-1@39.name": "PCF8574AT backed LCD@39",
    "registry.i2c-1@39.type.name": "I2C",
    "registry.i2c-1@39.description": "I2C-1.39"
  }

Notes

• All info about the Pi4J project can be found on pi4j.com.
• TODO: describe this Spring Boot Starter on the Pi4J website.

Thanks to

This project was started by Daniel Frey and got further improved by DaShaun Carter during a few live-coding sessions:

1. Working on Pi4J Spring Boot
2. Spring Boot Pi4J Starter :: Testing my PR