# Kotlin on the RaspberryPi (Pi4J-Kotlin)

> Learn about Pi4J-Kotlin, providing a Kotlin DSL for the already-mature Pi4J V2 API and take full advantage of Kotlin on the RaspberryPi!

- URL: https://foojay.io/today/kotlin-on-the-raspberrypi-pi4j-kotlin/
- Published: 2022-11-17
- Authors: Muhammad Hashim
- Categories: Embedded, Kotlin, Pi4J, Raspberry Pi, reactive


## Intro

[Pi4J](https://pi4j.com/) is considered the project that brought the JVM to the RaspberryPi.

It has been up for more than a decade allowing developers to write sophisticated, high-level, yet simple software on the RaspberryPi.

And we're glad to make it even more simpler and powerful!

For quite some years now Kotlin has been a most welcome language in the JVM ecosystem and the modern development toolchain.

Many factors led to this great reality, most notable to me is Kotlin's non-disruptive integration and seamless developer experience.

Enough reasons for us to bring it over to the RaspberryPi Community!

## Pi4J-Kotlin

Our latest project, [Pi4J-Kotlin](https://github.com/Pi4J/pi4j-kotlin), provides a Kotlin DSL for the already-mature \& capable Pi4J V2 API. You can take full advantage of Kotlin on the RaspberryPi and write even more capable and concise code for your projects.

## Blink if you can hear me

A blinking LED example is a benchmark for code simplicity (*at least for me, just pretend* ). Here's how to blink with `Pi4J-Kotlin`:

```kotlin
fun blink() = digitalOutput(22).run {
    while (true) {
        toggle()
        sleep(500)
    }
}
```

We also have a [minimal example](https://pi4j.com/kotlin/minimal-kotlin-example/) to get you started with more components.

## Declarative API

All you have to do to access everything-RaspberryPi is to use the `pi4j` block:

```kotlin
pi4j {
    // beautiful code goes here
}
```

Here, you created a Pi4J `Context` that will take care of loading the right `Platform` and `Provider`s. It will also automatically `shutdown` the `Context` after you finish the block. *That's right you no longer have to worry about opening or closing doors; you don't have time for that!*

Please never mind my bitter alter ego and let's discover some other exciting APIs:  

Using the `digitalInput` function you can easily create and customise your "*pin*" using this intuitive DSL:

```kotlin
digitalInput(address = 24) {
    name(“Button”)
    pull(PULL_DOWN)
    debounce(3000L)
}
```

In the same fashion, Analog and PWM get their fair share of sweetness:

```kotlin
analogOutput(24).run {
    whenInRange(0..5) {
        // fires when value is in the supplied range
    }
    whenOutOfRange(0..5) {
        // fires when value is not in the supplied range
    }
    onMin(0..5) {
        // fires when value changes to the minimum of the range
    }
    onMax(0..5) {
        // fires when value changes to the maximum of the range
    }
}
```

And of course we would take full advantage of the intuitive \& inlined lambdas of Kotlin to create APIs like these:

* `listen { … }`
* `onLow { … }`
* `onHigh { … }`

Be it Digital or Analog IO you'll find a little API that makes life even more convenient for you *(as if what you had wasn't already enough)* .  

Confused as you are, you might want to check the [full documentation](https://pi4j.com/kotlin/kotlin-api-docs/) on these new APIs and lots more.

## The story doesn't end

There are still more DSLs on their way for communication protocols and standards like **SPI** , **I²C** and more!

## Tell us what you think

Try it out! Tell us what you think and give us some ideas! Here is the [GitHub Repository](https://github.com/Pi4J/pi4j-kotlin).