Pi4J - Kotlin

Kotlin Interface & DSL for Pi4J.

For Pi4J V1 Kotlin Bindings, check Pi4K (no longer supported).

Documentation

Full documentation can be found on the website

Modules

Module	Artifact	Description
lib	pi4j-ktx	Core Kotlin DSL for Pi4J (digital/analog GPIO, PWM, I2C)
lib-serial	pi4j-ktx-serial	Serial communication DSL wrapping jSerialComm

Example

This is a minimal working example, make sure to check it out for full introduction and comments.

const val PIN_BUTTON = 24 // PIN 18 = BCM 24
const val PIN_LED = 22 // PIN 15 = BCM 22
var pressCount = 0

console {
  title("<-- The Pi4J Project -->", "Minimal Example project")
  pi4j {
    digitalInput(PIN_BUTTON) {
      id("button")
      name("Press button")
      pull(PullResistance.PULL_DOWN)
      debounce(3000L)
    }.onLow {
      pressCount++
      +"Button was pressed for the ${pressCount}th time"
    }

    digitalOutput(PIN_LED) {
      id("led")
      name("LED Flasher")
      shutdown(DigitalState.LOW)
      initial(DigitalState.LOW)
    }.run {
      while (pressCount < 5) {
        +"LED ${state()}"
        toggle()
        sleep(500L / (pressCount + 1))
      }
    }
  }
}

Serial

Serial communication is provided by the pi4j-ktx-serial module, which wraps jSerialComm (independent of Pi4J core since serial was removed in Pi4J 4.0.0).

Gradle setup:

dependencies {
  implementation("com.pi4j:pi4j-ktx-serial:4.0.0")
  implementation("com.fazecast:jSerialComm:2.11.0")
}

Usage:

import com.pi4j.ktx.io.serial.serial
import com.pi4j.ktx.io.serial.open

serial("/dev/ttyS0") {
  baudRate = 115200
  dataBits = 8
  // stopBits, parity, flowControl also available
}.open {
  // `this` is a jSerialComm SerialPort
  // port is automatically closed when the block exits
  outputStream.write("Hello\n".toByteArray())
  val response = inputStream.bufferedReader().readLine()
}