After using the GFX HAT for a few days I have, unfortunately, noticed a few hardware/software problems and niggles.
The backlight LEDs get very hot at full brightness. My pibowed Pi3B+ plus GFX HAT would make a good pocket hand warmer! After a couple of hours the heat also, in my opinion, starts to affect the LCD panel and the contrast isn’t as good, see next problem.
The display contrast is set to a fixed value during init in the st7567 driver. I suppose this is very easy to change in the software and bring it into the GFX library, but it’s annoying that it can’t currently be changed at runtime.
For example, full blue swamps the display and the contrast is, in my opinion, very poor.
There is an enormous amount of light “leakage” around the display, which actually makes it harder to see what’s being displayed! Whatever you choose as a backlight setting, the border is always brighter, particularly the top edge.
I have the impression that the LEDs are shining parallel to the display, and are mostly going straight through the top of the display housing, instead of properly illuminating the display diffuser. The actual display is relatively dim compared to the border.
EDIT: The more I squint at it, the ‘diffuser’ appears to be mostly a mirror, I hope I’m wrong.
The transparent border seems to be ‘standard’ for this display. The displayotron LCD has that black perspex border, for minimal light leakage at the sides.
I’m just wondering if here we’ve finally got the situation of actually having too many LEDs. I know it’s a shocking thought, but maybe this time it’s true?!