Black screen and strange display

[randoum]

Hi there,

I have no idea what I'm doing, I never work with electronic projects before, and I'm a total noob. Please bear with me.

I'm building a variometer (that thing telling you if you climb or descend) to fly my paraglider. There is this open source project https://prunkdump.github.io/GNUVario-TTGO-T5-website-EN/code/recup_code.html that I'm following. Here is the code I used to upload into the board https://github.com/prunkdump/GNUVario-TTGO-T5/tree/master/Sources/Beta%20Code/Ide%20Arduino/Gnuvario-E (the libraries are in the parent directory).

The upload works well, but the screen display is not normal: lots of black pixels where they are supposed to be white, and later half the screen has a black background while the other half has a white background, and the refresh rate is very slow. It does not behave as expected.

I know the code to be working correctly on other variometers.

This is the board I'm using https://aliexpress.com/item/4000384679772.html

For testing, I've uploaded this https://github.com/Xinyuan-LilyGO/LilyGo-T5-Epaper-Series/tree/master/examples/GxEPD_Example to check if the screen works well, and it works as expected without any of the weird behaviors described above.

I naively thought I just have to compare things between the GxEPD_Example and Gnuvario-E codes and find out how to fix the issue, but after countless hours trying to compare files I could not find anything relevant. To be honest I don't even know what I'm looking for.

So if someone could have a look, it could be obvious for you (I hope) and I'd greatly appreciate any pointers.

Best!