This whole project began last year with the idea of a stand alone hiking navigation system that does not rely on an internet connection, has a minimalistic user interface and is readable in bright sunshine. Brainstorming the whole idea lead to this project. A outdoor navigation system working by GPS positions only and not connected to the internet.

We started building a prototype by combining a 7-color ACEP display on a SPI interface board with an STM32, SD-Card, GNSS module and some capacitive touch buttons on a second board. Cobbled together the prototype and found all the issues with the design.

After I built the first firmware prototype we got a feeling on how much resources we will need for the final version. So we decided to pivot away from STM32 and moved everything over to ESP32. The STM32 was there in the first place, because I have a lot of experience in building low power applications with STM32. ESP32 now allows for integrating some kind of Internet connectivity.

Currently we have prototype hardware 2 running with ESP32 as a controller, the display directly connected to the Board (no SPI interface board) and a different GNSS module. The old Module did have issues with position drift.

One mayor issue we have at the moment is that the display starts out working as intended but over time degenerates into something like this:

Resetting the whole system does nothing and we are currently on the look out for what is causing the tint and how to avoid it. A second display does not come with the tint but instead comes with colours missing. So maybe we have an issue with inductance on the traces or the on board boost circuit or the register settings inside the display got bust. We are investigating.

Development of the project is streamed live on Twitch. You can follow me or my buddy. Stream language in German but you are welcome to join and I give you a short rundown of the project.