Category Archives: PCB

Prototyping and testing of the balancing robot

Leave a Reply

Made some progress on the balancing robot project. In this video, I made the first version of the PCB. It had a few problems but I still got the robot to balance. Some of the problems included:

  • Design error with the voltage divider and filter capacitor for the battery voltage measuring. Capacitor blew up 🙂
  • I forgot to connect the MISO, MOSI and SCK lines for the SPI bus.
  • Problem with the fotprint for the wireless module.
  • And a few more minior things…

Apparently, I need to check everything more carefully. Especially with the schematic, before I start to design the PCB itself. I hade also learned from many previous PCB projects that I have made, including this one, that you always need to create important/special component footprints yourself. Comunity-made footprints always have some errors, or something just decisions that I don’t like/want. Enev official footprints for components can have major problems.

In this video, I also show some of my planning of the remote controller for this robot. It will be a custom remote controller with an LCD and two analog control sticks. The controller should be able to control the robot, maybe in different ways. It will also have some kind of menu system for making adjustments to PID values and other settings.

Robot balancing by itself. The battery is just laying there on top. The robot will of course have a top plate for the battery when it is done.
Detailed shot of the first version of the PCB. Here you can also see the wires I had to solder on the connect the PIS bus for the IMU sensor.

DIY FrSky telemetry multi-sensor

2 Replies

I made my own “multi-sensor” for the FrSky radio system. An Arduino Nano reads a few different sensors and sends all the data to the Smart-Port connector on the RC receiver. This way I can get information such as battery voltage, speed, altitude, GPS position, and temperatures on my RC Radio when I fly my RC planes. This is perfect for planes that don’t have a flight controller onboard.

My design and hardware is based on the FrSky library from Pawelsky: https://www.rcgroups.com/forums/showthread.php?2245978-FrSky-S-Port-telemetry-library-easy-to-use-and-configurable

I actually started experimenting with making my own telemetry sensors a few years ago. Therefore my code is actually quite old. Back then, this was the only library available. I still think it works well, but today there are also other alternatives available.

At first, I just soldered a GPS and a servo connector to an Arduino NANO. But later I made a few PCBs to make them easier to assemble. My first versions had voltage monitoring of the individual cells in the flight battery, but I found that it was annoying having to plug in the balance connector of the battery in the plane.

This is my third iteration of the board. It has a single input for LiPo battery voltage monitoring with a voltage divider and filter capacitor, a BMP280 barometer for altitude and variometer measurements, a connection for a Beitian BN-220 GPS or any other NEMA capable GPS for speed and position data, and two Dallas DS18B20 temperature sensors, one onboard and one attached with cables.

Update 2022-01-07: I fixed an error in the PCB design and made a few small adjustments in the code. The links are now the updated versions.

Link to my schematic and PCB: https://oshwlab.com/Axbri/frsky-telemetry-v3

Download link for my code, schematic and PCB gerber-files:
Axels FrSky tememetry sensor V4.zip