The GNS 430 GPS

Originally published 1. May 2024

The first device I built was the GNS 430 GPS unit. Here's the finished thing:

I wanted this to have with backlit buttons and real dual rotary encoders. After searching the web for a while it became clear, that I had to design this myself.

The screen content comes directly from the flight sim. But since I'm currently running the sim on a Macbook Pro, and thus do not have an option to connect too many external displays, I use AirManager for grabbing the GPS' display content directly from XPlane and sending it via a network connection to a Raspberry Pi 4. This works surprisingly well, even over wifi. Unfortunately the Raspberry doesn't have enough GPIO pins to also drive all the buttons and encoders. I originally planned to build two GNS 430 units anyway (as there are two of them in the simulator) and it's no problem for the Raspberry Pi 4 with its 2 HDMI connectors (and the AirManager/AirPlayer combo) to provide the display content for both of them. So I decided to use a separate Arduino Mega 2560 for interfacing with all the hardware buttons and encoders. To my pleasant surprise, it's even possible to connect the Arduino(s) directly to the Rasperry Pi and setup AirManager/AirPlayer in such a way, that all information is transported via the netrwork connection. This greatly reduces the need for cables between the dashboard and the computer. In fact, there is actually 0 (zero) cables between the main computer and the dashboard, since everything is working great so far with just a WiFi connection between the Mac and the Raspberry Pi. The only cable going to the dashboard is a power cable!

Here's the current wiring schematic of the GNS 430:


I did draw the whole design in Fusion. I was able to use some parts (like the rotary encoders) from GrabCAD, but most parts (including the backlit push buttons and the LCD) I drew myself.



After a few failed test prints of the tiny push button covers with my > 10 years old LulzBot TAZ 6 it was clear, that a FDM printer wouldn't cut it (at least mine). So after more than 15 years of FDM printing, I decided that it would be time to give resin printers a try and bought a Elegoo Mars 3 Pro.

Using a resin printer after years and years of FDM printing is maybe a story for a different time, but I finally managed do successfully print first push buttons!

I printed these with clear resin and airbrushed them black afterwards. Finally I sanded off the black coating from the embossed text and voila: A backlit push button:

I ordered most of the hardware for cheap from Ali Express (rotary encoders and a bag of 100 pcs "6x6x7mm through hole reset micro push button tactile momentary switch with led (white)"), and a 4 inch IPS display with HDMI port from Amazon (not so cheap).

The white text on the frontpanel and the encoder knobs is also 3D printed, embossed text. But this time the part was printed with black resin and the embossed text later painted white (with a white paint pen).

And here's the thing, all cabled up, after assembly:

On the software side, I wrote a LUA script for my GNS 430 in AirManager.

The LCD-Content is fetched from XPlane and send to the AirPlayer instance on the Raspberry Pi with this simple command:

video_stream_id = video_stream_add("xpl/GNS430_1", 0, 0, 800, 480)

All the buttons and encoders are then mapped by a script, running on the Arduino Mega.

Update March 2026:

Since the original build (about two years ago), I ran into various issues with the AirPlayer setup on a separate Raspberry Pi. With almost every AirPlayer software update, the setup broke in one way or another, and eventually the video stream stopped working entirely.

After many hours of reconfiguring and trying to fix the issues with help from Air Manager support, I finally gave up and removed the Raspberry Pi with AirPlayer from the setup.

At the moment, I’m running the Arduino for the buttons directly via USB from the main computer, and the LCD screen is now connected via HDMI through a USB-to-HDMI adapter, also directly to the main machine. X-Plane sees it as an additional external monitor.

While the wireless setup over Wi-Fi with AirPlayer was quite nice, it became much less important once the project shifted from a “quickly set up and taken down desktop dashboard” to a more or less permanent full-size cockpit.

All Software can be found in my github repository for this project: https://github.com/zaggo/CockpitDrivers

If interested, you'll find the most recent lua scripts for AirManager here:

https://github.com/zaggo/CockpitDrivers/tree/main/etc/AirManagerCleartextLUA

The Fusion files for the GNS430 are available as .f3z files in this Repo: https://github.com/zaggo/PA28Cockpit

Comments

Post a Comment

Popular posts from this blog

Setting up a new (blog-) home for my build log

Image
Hi, After starting a build log for this project on hackaday.io a few years ago, I ran into issues with how the build logs are organized there. So I decided to move my build log for my DIY flight sim cockpit here. I’m hoping this move will make it easier to post updates more regularly and keep track of the project’s progress. I’ll be moving my existing posts over from the old build log and then share an update on where the project currently stands, along with the next steps. So, here’s what’s happened so far… The Beginning (January 2024) Piper Arrow III Sim Cockpit Originally, I set out to build a dashboard for a Piper Arrow III for use with flight simulators. The idea was to keep it modular so it could be set up and taken down easily on a desk, since I didn’t have space in my apartment for a full, stationary cockpit. The setup was meant to be centered around my CH Products yoke and rudder pedals, which I had already owned for years. Since then, the scope of the project has evolved quit...
Read more

Merry Chistmas…

Image
Originally published 23. December 2024 I already finished the Attitude Indicator. I plan to do a more detailed writeup and a video on this one, so for now, only to images. From the front, it looks more or less like any other DIY Attitude Indicator. However, while it is almost never needed during normal flight, I have always disliked the fact that most DIY Attitude Indicators have a roll limit to avoid tangling the wires. One solution could be to use a slip ring for the cables of the pitch motor or servo. However, my idea was to over-engineer the entire thing by designing it with coaxial motor shafts, placing both motors for the two axes outside the moving cage. The truly challenging part was getting the software to work. Over the last two weeks, I’ve been designing and building an HSI from scratch. I couldn’t find any DIY versions of an HSI. Since a typical HSI requires (at least) five axes to operate (six in my case), I quickly decided to keep the mechanics as simple as possible and u...
Read more