Pi4J on foojay.io - Friends of OpenJDK

Using the Raspberry Pi Sense HAT with Pi4J Drivers

Wed, 01 Jul 2026 08:38:00 +0000

One of the biggest advantages of the Pi4J Drivers project is the ability to interact with complex hardware through simple and intuitive Java APIs. A great example of this is the Raspberry Pi Sense HAT, one of the most popular Raspberry Pi add-on boards and the hardware platform used in the Astro Pi program aboard the International Space Station.

Instead of manually implementing communication with multiple sensors and devices, Pi4J Drivers provides a ready-to-use driver that makes accessing the Sense HAT straightforward and enjoyable.

Pi4J Drivers: Simplifying Sensor and Hardware Integration in Java

Thu, 25 Jun 2026 07:07:08 +0000

When developing Java applications for Raspberry Pi, Pi4J is one of the most popular libraries for accessing GPIO, I2C, SPI, PWM, and other hardware interfaces. However, interacting directly with these protocols often requires a significant amount of code and a deep understanding of the underlying hardware.

This is where the Pi4J Drivers library become extremely valuable.

What is Pi4J Drivers?

Pi4J Drivers is a companion project to Pi4J that provides ready-to-use drivers for a wide range of electronic components, including sensors, displays, I/O expanders, and actuators. Instead of implementing low-level communication from scratch, developers can leverage tested and reusable APIs to interact with hardware devices.

Bringing Raspberry Pi Development to Quarkus with the Quarkus Pi4J Extension

Tue, 23 Jun 2026 07:30:00 +0000

Java developers building applications for Raspberry Pi often face a common challenge: combining hardware access with modern application frameworks.

Pi4J has become the standard way to access GPIO, I2C, SPI, UART, and other Raspberry Pi interfaces from Java applications. On the other hand, Quarkus has established itself as one of the most innovative Java frameworks, offering fast startup times, low memory consumption, and a developer-friendly experience.

The Quarkus Pi4J Extension brings these two worlds together, making it easier than ever to build hardware-enabled applications using the Quarkus ecosystem.

Research: Measuring Energy Consumption in Programming Languages for AI Applications

Mon, 15 Sep 2025 07:03:00 +0000

Decades ago, I contributed to a very interesting project called SunSPOT at SUN Microsystems. It was a small device with wireless connectivity, built-in sensors, running on Java (compatible with runtime 1.6), and powered by battery. It enabled the design of small applications and the connection of additional hardware, or simply the utilization of available sensors. Later, together with Markus Hirt, we created the Robo4j framework . A small and lightweight Java framework that enables rapid assembly of robots or other IoT systems (JDK 21+). In Robo4j, we primarily used thePi4j project for handling I/O operations on the Raspberry Pi platform with drivers created for specific hardware.

Pi4J Welcomes Java 21 on the Raspberry Pi

Thu, 20 Feb 2025 10:49:07 +0000

Pi4J provides a friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform.

The project “hides” the complexity to interact with electronic components through different ways of communication (SPI, I2C, PWM,…) by providing Java interfaces on top of native libraries that can interact with the GPIO (General Purpose Input/Output) pins on the Raspberry Pi.

Recently, the development of the Pi4J library faced a decision point: “Should we stick to Java 11 for existing projects and old Raspberry Pi’s (with ARMv6 ), versus moving on and making use of better and more performant Java code with the latest Long Term Support (LTS) version?”

Deep dive into bits, bytes, shorts, ints, longs, signed, and unsigned with Java

Fri, 18 Oct 2024 13:54:09 +0000

On the Pi4J discussion list, someone recently asked what the best and easiest way is in Java to convert a byte value . In Java, there is no distinction between signed and unsigned bytes, which can be confusing. My book “Getting Started with Java on the Raspberry Pi” contains an explanation about this, and I am happy to share it in this post with some more info and code examples…

Foojay Podcast #55: Embedded Java, Part 2

Mon, 01 Jul 2024 08:21:42 +0000

As a backend developer, you may not realize that Java was initially born on embedded devices like set-top boxes and gateways. We discussed this topic for the first time almost three years ago in Foojay Podcast #2 with James Gosling, Johan Vos, Erik Costlow, and Frank Delporte .

In this episode #55, we look into the history of the Java Micro Edition and how things evolved. Nowadays, with processors becoming increasingly powerful, we can run the exact same Java runtime on any Linux system, from the biggest cloud servers to the smallest Raspberry Pi Zero.

Evolutions in the Pi4J library by Tom Aarts and Robert von Burg

Fri, 24 May 2024 12:16:02 +0000

Multiple improvements have been implemented in the new release, V2.6.0 (2024-04-29) of Pi4J, a friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform. This blog post will give you a quick overview and an interview with Tom Aarts and Robert von Burg, two of the main contributors.

Ongoing I2C Improvements
PWM Hardware Support on Raspberry Pi 5
New Class to Get Board Info
Interview with Robert von Burg
Interview with Tom Aarts
Conclusion

Ongoing I2C Improvements

Robert von Burg worked on improvements to the I2C implementation in Pi4J. The changes are in pull request #351 and allow atomically executing multiple I2C calls in a thread safely, plus other improvements. See this blog post for more details .

Java on Raspberry Pi 5 with Pi4J

Sat, 06 Apr 2024 11:08:20 +0000

In October 2023, Raspberry Pi announced version 5 of its affordable single-board computer with 4GB (60$) or 8GB (80$) of memory.

Soon after the first boards were delivered, it turned out the Pi4J library wasn’t compatible with this new board. Pi4J is a library to create Java applications for the Raspberry Pi that can interact with electronic components through the GPIO pins.

But because the Raspberry Pi 5 uses a new approach, with the new RP1 chip , to connect the SoC with these pins. Thanks to the RP1, it was possible to seperate GPIO, SPI, I2C, USB, ethernet,… from the SoC to make it easier to develop newer boards. However, this new approach wasn’t supported by the PiGpio library used in Pi4J V2.

Controlling LED Strips with Java and JBang

Mon, 22 Jan 2024 18:08:51 +0000

One of the most “fancy” electronic components is definitely… a LED strip. It’s really cool to control a long strip of lights with only a few lines of code.

But, there is a problem. The timing of the signals is crucial to reliably control these strips. Both Python and Java on a Raspberry Pi can struggle with these timings as they are running on Linux, a non-real-time operating system.

So, for instance, pauses in the garbage collection of the Java virtual machine, or any glitch in the operating system can cause unexpected effects on the LED strips. That’s why in most projects, a microcontroller (Arduino, Raspberry Pi Pico, ESP32,…) is used to drive the LED strip.

Pi4J Operating System for Java development on Raspberry Pi

Fri, 11 Aug 2023 10:19:50 +0000

Yes, the Raspberry Pi Operating System is awesome! But the Pi4J project made it even more awesome by adding “goodies” for Java developers! Pi4J OS is not yet another OS, but the official Raspberry Pi OS, with additional tools and preconfigurations to make it the ideal OS for any Java and JavaFX developer who wants to use a Raspberry Pi.

The project is shared on GitHub and documented on the Pi4J website . The zip-compressed archives of released versions can be downloaded from pi4j-download.com .

Temperature, humidity, and pressure in BME280 Sensors with Java

Thu, 03 Aug 2023 07:16:36 +0000

To make it as easy as possible to get started with Java on the Raspberry Pi to interact with electronic components, I started a new section on the Pi4J website with JBang examples .

In this tutorial, I want to show you how you can read the temperature, humidity, and pressure from a BME280 Sensor.

What Is Used?

As explained on the websites of each project:

Pi4J

A friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform. This project abstracts the low-level native integration and interrupt monitoring to enable Java programmers to focus on implementing their application business logic.

Coroutines on the RaspberryPi (Pi4J-Kotlin)

Sat, 01 Apr 2023 09:05:29 +0000

If you didn’t know already, Pi4J has had a Kotlin DSL for quite some time now.

And I’m here to announce the latest release v2.4.0 with a sack of additions and to tell you about all the good stuff that’s been added since the first release .

Coroutines {#h2-0-1-coroutines}

If the pi4j { ... } wasn’t good enough for ya, and you want to use coroutines instead of weaving fat threads on your precious precious Pi, you can now use the new pi4jAsync { ... } block—It can do everything pi4j { ... } does + you can run suspended functions within.

Controlling a LED Strip with Pi4J and JBang

Mon, 28 Nov 2022 13:07:06 +0000

In an earlier post here on Foojay.io, JBang and Pi4J were used to control a LED and button connected to a Raspberry Pi .

This week Robert von Burg, one of the main contributors of the Pi4J project, shared on Mastodon another project where a LED strip is controlled via I2C.

This is the result, notice the Foojay.io startup artwork 😉

Wiring

The Raspberry Pi in the video is attached to a custom PCB used by Robert in medical cabinets .

Kotlin on the RaspberryPi (Pi4J-Kotlin)

Thu, 17 Nov 2022 13:37:18 +0000

Pi4J 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.

Pi4J V2.2.0 Released

Wed, 31 Aug 2022 17:09:19 +0000

One year after the first release of V.2 of Pi4J , a new release was published. Pi4J providesfriendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform.

And what an amazing achievement with this new release! No major issues were found in the previous release, but several small fixes were added by more people than ever before in the Pi4J-history. This is a real confirmation of the openness of this project and how a community can work together to further improve a project.

Blink a LED on Raspberry Pi with Vaadin

Fri, 25 Mar 2022 14:44:02 +0000

As I’m becoming a senior developer, at least in terms of age, I’ve transitioned from one language to another.

One of my main interests has always been clean, easy-to-understand UIs (User Interfaces). That journey started for me with Director (to create multimedia CD-ROMs), Flash website animation, and Flex Rich Internet Applications (= “Flash on steroids”).

When I started developing with Java over 10 years ago, we had some projects with the early versions of Vaadin and JavaFX.

Controlling Electronics with JBang on the Raspberry Pi

Mon, 21 Feb 2022 10:08:06 +0000

Want to get started with Java programming on the Raspberry Pi?

JBang is a great way to create your first program to control electronic components connected to the GPIO pins.

What is JBang?

As described on their website :

JBang lets Students, Educators and Professional Developers create, edit and run self-contained source-only Java programs with unprecedented ease.

Want to learn, explore or use Java instantly without setup?
Do you like Java but use python, groovy, kotlin or similar languages for scripts, experimentation and exploration?
Ever wanted to just be able to run Java from anywhere without any or very minimal setup?
Ever tried out Java 11+ support for running .java files directly in your shell but felt it was a bit too cumbersome?

JBang lets you do all this!

Template to Get Started with Pi4J and JavaFX on Raspberry Pi

Thu, 13 Jan 2022 12:07:26 +0000

The Pi4J project wants to be the starting point for everyone who wants to use Java on the Raspberry Pi, being it a headless, JavaFX-user interface and/or GPIO-controller project.

Pi4J is intended to provide a friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform . This project abstracts the low-level native integration and interrupt monitoring to enable Java programmers to focus on implementing their application business logic.

Java Modules in the Pi4J Project?

Thu, 23 Dec 2021 15:28:39 +0000

Java modules have been a big discussion point before in many places.

And this is now also causing some headaches in the Pi4J project…

About Pi4J V2

The Pi4J project (started in 2012) aims to unite Java programming with electronics. By using the Pi4J dependency in a project, electronic components connected to the GPIO-pins (General Purpose Input/Output) of the Raspberry Pi can be controlled as objects in the Java code. Pi4J uses native libraries to control the GPIOs so you - as a programmer - donʼt need to be fully aware of all the “magic” that relates to hardware communication.

MQTT on Raspberry Pi (Part 2)

Wed, 22 Dec 2021 14:58:21 +0000

In the previous post we started our discovery of HiveMQ Cloud with Java on the Raspberry Pi. We created an application to send measurements of various sensors to the HiveMQ Cloud MQTT broker. Using an online websocket client we verified the transition of the messages, and could see the data being published to this online message queue.

Now we will take the next step and subscribe to these topics to receive the data in a dashboard, created with JavaFX.

MQTT on Raspberry Pi: Sensor Data to HiveMQ Cloud with Java and Pi4J

Wed, 15 Dec 2021 09:54:37 +0000

A few years ago I did my first experiments with an MQTT server (Mosquitto) running on a Raspberry Pi to connect an Arduino and Raspberry Pi for the drumbooth of my son . The full process is described in my book “Getting Started with Java on the Raspberry Pi” .

In this series of articles we are going to take a different approach with an online MQTT-compatible service: HiveMQ Cloud . The biggest advantage: no need for an always-on server we must manage ourselves. Yes, Mosquitto runs on a inexpensive Raspberry Pi, but still we require to keep it up-and-running if we use it as the “central hub” to distribute data.

Getting Started with Java 17 on the Raspberry Pi

Sat, 25 Sep 2021 13:56:53 +0000

As part of the Foojay Virtual OpenJDK 17+ JUG Tour , I was asked to present the state of Java and JavaFX 17 on the Raspberry Pi.

So, a perfect opportunity to freshen up my #JavaOnRaspberryPi presentation with some hot-off-the-press versions.

UPDATE 2021-08-30: the recording of the presentation has been published on YouTube.

In the past, I have been experimenting with Java 16 on the Raspberry Pi (see “Building OpenJDK from GitHub Sources on 64-bit Raspberry Pi ”) but now that version 17 is waiting around the corner, it’s time to prepare our Raspberry Pi for the upcoming new “long-term-supported” (LTS) version.

Announcement: Pi4J V.2 Released!

Mon, 30 Aug 2021 12:13:54 +0000

After long rework, the Pi4J library (a friendly object-oriented I/O API and implementation libraries for Java Programmers to access the full I/O capabilities of the Raspberry Pi platform) has taken a big step with the first release of the V.2.

The Pi4J Project was started in 2012 by Robert Savage , the same year the Raspberry Pi was introduced as a tool to provide Java developers a simple and familiar object-oriented interface library to access the low-level I/O capabilities of the Raspberry Pi including GPIO , I2C , SPI , PWM , and Serial communications. Pi4j program structure

Schedule for Foojay Virtual OpenJDK 17+ JUG Tour

Tue, 10 Aug 2021 12:04:52 +0000

As announced last month , to celebrate the OpenJDK 17 and Foojay.io as a vendor-neutral community platform for its users , we’re kicking off the Virtual Foojay JUG Tour to be held during and around its release month of September.

And here’s the schedule, note that it will change as more meetups are confirmed, and if your JUG is missing, i.e., you’d like to still be included in the tour, no worries, let’s see what can be done, simply contact JFrog’s Ari Waller (ariw at jfrog dot com) and Payara’s Jadon Ortlepp (jadon.ortlepp at payara.fish), Foojay’s Event Managers, and specify a date and time (and preferred topics ) together with some dates and times that would work for your JUG.

Foojay Podcast #2: Embedded Java -- Robots and FX

Thu, 22 Jul 2021 14:13:32 +0000

Foojay community members and beyond discuss embedded Java:

James Gosling , creator of Java and embedded enthusiast. Distinguished engineer of AWS GreenGrass and former Liquid Robotics, an autonomous ocean vehicle powered by water.
Frank Delporte , engineer with Toadi, an autonomous lawn-mowing robot (no wires) and Pi4J contributor of Raspberry-pi based robots.
Johan Vos , founder of Gluon, helping make fully cross-platform applications where a single JavaFX codebase runs natively on embedded, iOS, Android, PCs, and browsers.
Erik Costlow , developer relations for Contrast Security, locating security flaws in backend systems. Developer of home fuel/gas sensors.

Podcast Apps

You can listen and subscribe to the Foojay Podcast on:

Announcement: Virtual Foojay OpenJDK 17+ JUG Tour

Wed, 21 Jul 2021 16:07:16 +0000

To celebrate OpenJDK 17 and Foojay as a community platform for its users, we’re kicking off the Virtual Foojay OpenJDK 17+ JUG Tour, focused on OpenJDK 17, plus more!

Ari Waller, JFrog’s Event Manager, well known to many JUGs, will continue to wear a second hat, as he did on the previous tour—that of Foojay Event Manager, together with Jadon Ortlepp from Payara, newly added to the Foojay Event Team!

Java in Education: Combining Java with Raspberry Pi and the Pi4J Library

Tue, 29 Jun 2021 07:40:55 +0000

The interviews in this post are part of an article published (in German) in Java Magazine . You can get a 25% discount for a new kiosk subscription with the following code: delporte_kiosk25

Although a lot of universities and high schools focus on Python and C# in their program, there are luckily a lot of others who go “full Java”. Don’t get me wrong, I definitely don’t want to start a “programming-languages-war”, but Java is the language I used myself more than any other for the last 10 years. Setting up a new project or building a proof-of-concept for a new idea, is a matter of hours. And there is always a solution for the problem I need to solve. This is probably true for each developer who has enough experience in the language used the most. But having used and experimented with many other languages, I still keep returning to my “one true love”, being Java, as it always delivers the result I’m aiming for, with the right amount of code to be readable, understandable, and testable!

Gluon Update, Dual Screen Raspberry Pi , IntelliJ JavaFX Project Wizard

Fri, 04 Jun 2021 07:27:41 +0000

Last week, Johan Vos of Gluon, released a video with a status update of JavaFX. In this post we are going to take a deeper look into one of the announcements: dual screen support on Raspberry Pi.

Announcements by Gluon

Since Java switched to a 6-month release cycle, JavaFX has done the same, so next version will be number 17. Keep in mind, although Java and JavaFX are on the same version-number, you can still use Java 11 and combine it with the JavaFX 17 runtime if you want to benefit from its improvements. Up till now, there were no breaking changes in either of the frameworks which force you to use a Java-version higher than 11.

Interviews with Robert Savage & Johan Vos on Java on the Raspberry Pi

Fri, 28 May 2021 07:14:26 +0000

This post is part of an article published (in German) in Java Magazine . You can get a 25% discount for a new kiosk subscription with the following code: delporte_kiosk25

Here on Foojay.io, you can find already a long list of articles about Java on the Raspberry Pi . As you may know, already I’m a big fan of this combination. The Raspberry Pi on one side is a very cheap computer that allows you to experiment with electronic components thanks to the Pi4J library. And on the other hand, JavaFX is the ideal framework to build user interfaces that can directly control these components, all in one application!

Snake Game with JavaFX FXGL in Three Pair-Programming Sessions

Tue, 04 May 2021 07:00:00 +0000

In this article, Almas and I will show you how to start with an idea for a game and bring it to life in a prototype application. We will then modify the application to run on a Raspberry Pi and on a mobile device.

To give some background, some time ago my 10y old son challenged me to create a Snake-like game with emojis. He selected the emoji images and I “only” needed to do the programming bit, the easy part… Luckily Almas asked me if I had a topic for some pair-programming for his YouTube channel , and his question turned into a three-part series. My son is delighted because his idea is now a real game!

JavaFX Running in Kiosk Mode on the Raspberry Pi

Tue, 27 Apr 2021 14:39:50 +0000

Combined with an inexpensive touch screen, the Raspberry Pi makes for a perfect controller for a machine or game console. Let’s see how we can use Java and JavaFX to build a test application that also communicates with the pins of the Raspberry Pi to control a LED.

We have done something before already in the post “Light Up your Christmas Tree with Java and Raspberry Pi” , so what’s new here?

Announcing the Upcoming Virtual Foojay JUG Tour!

Tue, 26 Jan 2021 08:03:51 +0000

To celebrate the OpenJDK and Foojay.io as a community platform for its users, we’re kicking off the Virtual Foojay JUG Tour. Ari Waller, JFrog’s Event Manager, well known to many JUGs, now wears a second hat—that of Foojay Event Manager. During March and April, contributors to Foojay will be making a whistle stop tour through as many JUGs as possible, via their virtual meetups! (And if you’re not holding virtual events or don’t have the facilities for this, we can support by making these available as needed.)

Java Predictions for 2021: Raspberry Pi and Java

Sat, 26 Dec 2020 09:06:38 +0000

To celebrate the world of Java and predict some highlights for 2021, several key Foojay participants will share their thoughts and hopes during the coming days on Foojay, starting with Frank Delporte, Foojay Community Manager for the Raspberry Pi.

Looking back to my Java adventures in 2020, I can only conclude it has been a wonderful journey.

By writing my book “Getting Started with Java on the Raspberry Pi” (https://webtechie.be/books/ ) and blogging for foojay.io , I discovered Java in the embedded world has a very bright future. With the 6-month release cycle of both Java and JavaFX, a lot of improvements and new features that impact the use of Java on Raspberry Pi, are introduced with every new version.

Light Up your Christmas Tree with Java and Raspberry Pi

Wed, 23 Dec 2020 09:38:17 +0000

Are you a serious Java-developer looking for a fun project?

Or want to learn something completely new and use your Java-knowledge to control electronic components?

Here we go with this small project to get you introduced to the world of electronics programming!

This post was originally published on “JVM Advent - The JVM Programming Advent Calendar ”, a month-long reading list of diverse Java-related articles. A nice addition to your daily read of Foojay!

Electronics & Micronaut Velocity with Raspberry Pi

Tue, 06 Oct 2020 08:35:45 +0000

In a previous post, we looked at the project “Electronics & Quarkus Qute on Raspberry Pi ” by Igor De Souza .

In this article, we present you another great example of Java on Raspberry Pi created by Igor. It shows how to create a Micronaut Velocity demo using an 8x8 LED matrix display.

Micronaut

Micronaut is a JVM-based framework for building lightweight, modular applications. Developed by OCI , the same company that created Grails , Micronaut is the latest framework designed to make creating microservices quick and easy.

Electronics & Quarkus Qute on Raspberry Pi

Wed, 30 Sep 2020 08:07:13 +0000

The “Hello World” version of electronics programming is a blinking LED. But, in this post, we will go a few steps further and control 8 LEDs inside a number display.

We will do this by taking a closer look at one of the projects in the list “Spectacular Java Projects on the Raspberry Pi ”.

Igor De Souza , Dublin based Principal Big Data Consultant at Oracle, set up an interesting experiment in which he combines a LED number display with the Raspberry Pi and Quarkus.

Spectacular Java Projects on the Raspberry Pi

Wed, 23 Sep 2020 10:38:17 +0000

Thanks to Twitter and LinkedIn, I’ve been in touch with several developers who are doing cool Java stuff on the Raspberry Pi.

Here I want to share a number of projects with you, as they can be an inspiration for all of us to get started with Java development on the Raspberry Pi!

Igor Souza - Kafka on the Raspberry Pi

Igor shared this nice video where he set up a Kafka cluster on Raspberry Pi . He also has a nice example where this is combined with an e-ink display to show real-time bus information . Some of his work is available on GitHub where you can find Kafka and other example code .

Interview: Frank Delporte, Foojay Raspberry Pi Community Manager

Mon, 07 Sep 2020 13:20:38 +0000

Today we’d like to introduce a new community manager for all things Raspberry Pi on foojay: Frank Delporte!

Welcome, Frank! Tell us about yourself. 🙂

Hi, I’m Frank Delporte, living in Belgium. I started programming when I was 10 on my Commodore 64.

I started my professional career as a video editor for television, 25 years ago. I went through all stages from video, multimedia, websites to back-end development using different technologies.