One of the most read articles on this blog is about the installation of a recent Java on Raspberry Pi (March 13, 2019), so it’s time for an update!

Based on multiple examples from my book “Getting started with Java on Raspberry Pi”, I created a touchscreen controller for the drum booth of my son. Combined with relays boards and an Arduino this allows to control LED strips and different lights with a touch screen interface.

While looking for a cheap and nice component to demonstrate the use of SPI (Serial Peripheral Interface) I found out this 8x8 matrix LED display on a board with a MAX7219 chip is the perfect piece of hardware!

Pi4J contains helper methods to minimize the work needed to use certain hardware modules on the Pi with Java. As an example, we will be using “GpioLcdDisplay” to control an LCD with 2 rows of 16 characters. After requesting the weather forecast from a public website, we will visualize this on the LCD display.

Trisha Gee (Coder, blogger, speaker, Developer Advocate at JetBrains, @trisha_gee), which I interviewed for “Chapter 4: Choosing an IDE”, and Josh Long (Spring Developer Advocate at Pivotal, @starbuxman) worked together on a blog series in which they showed the power of reactive data produced by a Spring application. Instead of repeating a REST call each time you want to get data from the server, you do one call which returns a continuous stream in which new data is pushed based on an interval.

In my book I explain the use of bits and bytes by using a shift register SN74HC595 IC and 5101AS LED number display.

To create some timeline images for my book, I created this little JavaFX application to be able to easily update the content and recreate the image. Of course you can do the same in an image editor, but hey I’m a programmer and lazy, so I want a program to do the job for me ;-)

Using the Java library I created (see previous post), it was a piece of cake to create a JavaFX UI on top of it!

Next step in my book progress, is getting more into the details of hardware components. And as always starting with the smallest most-used ones: resistors!
To be able to fully document this for the book and create a demo application, I started again with creating and sharing a Java library.

The best way to understand and learn something new, is to document it yourself. That’s what I’m doing in every step for my book-in-progress. And to fully get the pinnings and headers of the different Pi-boards, I decided to gather all info into a Java library with different enums to be able to auto-generate some content for the book and use in a few different example applications.