Display driver for TTGO T-Watch and T-Watch 2020

[Ferdinand Jamitzky]

I would like to write a driver for the TTGO T-watch and the T-Watch 2020 which both have a ST7798V 2.4 inch 240x320 RGB display. Can I start with the M5Stack Core Display which has a 2 inch, 320x240 Colorful TFT LCD, ILI9342C, so it should be easy to do. I already managed to upload the VM to the TTGO T-Watch and connect it to the IDE, but the display says width=0 and height=0. What do I have to do?

[John Maloney]

First, you need to create an #ifdef entry for the TTGO T-watch in tftPrims.cpp, if you haven’t done that already. You can copy the entry from one of the other boards and modify it.

You’ll need to figure out out which pins to use in the constructor for your TFT display. The documentation and/or schematic diagram for the T-watch may help. You could also look for some Arduino code for the T-watch display and get the pin numbers from that.

Finally, you need to write a tftInit() function for your display. Again, it is helpful to use a working Arduino sketch as a model.

Good luck with the project!