This is an attempt to create a functional GPS lag for small sailboats. The hardware is based on ESP32, it currently uses ESP32-DevKit-C (a copy from Aliexpress), a QUESCAN G10A-F30 GNSS module and 4 inch Waveshare eInc display.
- ESP32 microcontroller - currently a ESP32-DevKit-C copy from Aliexpress. That's the brain of the device.
- Waveshare 4.2 inch eInc display - low power consumption, well visible in bright sunlight. Partial refresh is fast enought for a small sailboat that won't go faster that 8 - 10 knots. And because I had one laying around.
- QUESCAN G10A-F30 GNSS module based on the UBX-M10050-KB chip - supports multiple GNSS systems and has reasonable speed accuracy.
- LiIon battery module based on TP4056 - because I had it available.
- Some resistors and button to provide power on/off - actually deep sleep and wake up untill a more advanced schematics are implemented.
A prototype PCB design is avalailable in a separate repository.
This repository holds all the software for the device. Based on Platform.IO, and uses some functions from ESP-IDF by Esspressif. A fork of x99/NMEAParser is used for parsing NMEA sentences and zinggjm/GxEPD2 is used for drawing things on the eInc display.
We're hitting a limitation of the Adafruit_GFX library that provides graphics support for GxEPD2. Because it uses 8 bits for various font dimensions, and this limits the maximum font size that can be generated. My experiments got me 92px maximum font size, but that might depend on actual font used. The same 8 bits limitation also limits fonts to ASCII caracters only, which makes it impossible to use tabular numerals - fixed width font doesn't work well here.