When driving around in a new area, I’m often curious about the current elevation. And while my car, my phone, and my smartwatch all have GPS receivers, none of them have the option to display the current altitude while showing navigation instructions. So I decided to build my own.

I’m a big fan of the XIAO microcontroller boards from Seeed Studio . Their small size, USB-C connection, and Arduino support combine to make them my goto boards for most projects. I also have some small I2C OLED displays laying around. I wanted to use GPS to determine altitude and I didn’t one of those lying around, but Seeed has their L76K GNSS module that seems designed especially for XIAO boards, so I bought one of those to complete the parts list.

Adafruit also makes microcontroller boards in the XIAO form factor that they call QT Py. One benefit of these boards is that they include a Stemma/Qwiic connector for I2C communication. Since I would be using I2C for the display, and I already had a few QT Py SAMD21 boards on hand, I decided to use one of these for the project. The final design is relatively straightforward and just uses the QT Py to receive messages from the GPS, and translate them a format to send to the display.

The image below shows the system as currently setup in my car (please excuse the dirt). It could probably use an enclosure, but does the job for the time being. The final PlatformIO project can be seen here . Any questions or comments, please reach out to me on Mastodon: @jayemar@indieweb.social

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