Lately I’ve been playing with a Inky Impression 7 and 13 inch. Since I want my project to be portable, I’ve bought a Pisugar 3 since it doesn’t use any GPIO pins and I am still able to mount the Pi (Zero 2w) on the board.
I am able to run the Pi + Sugar with no problems on the 7 inch screen, but when I use it on the 13 inch screen, most of the time I am not able to update the screen (using the examples).
A strange thing I came across is when I disconnect the battery on the PiSugar and reconnect it (I’ve soldered a connector on it, normally the battery is hard-wired) the PiSugar (and therefor also the Pi) auto-boots. In this situation the examples are running and everything seems to work fine.
Here again, when I do a soft shutdown and restart everything manually, the screen doesn’'t update no more. The examples for led and buttons do work in every situation.
When I completely remove the PiSugar and directly power the Pi, everything works fine.
Can someone tell me why the 13” screen doesnt work with the Pi + Sugar config, but the 7” does?
Very interesting. I was considering buying the pisugar 3 for this exact setup. I wanted to use the witty pi 4 mini but that and the 13.3” screen both use pin 17 so I don’t know if that’ll be an issue(I’m a complete noob with all of this). It seems like the pisugar would solve all my issues, but it has mixed reviews with its connections… but if it doesn’t even work on the larger screen than it looks like I’m back to square 1 again.
I also bought the witty pi because I didn’t check GPIO usage. One other problem with the witty is that is using the gpio pins, so to connect it to the Inky impression you’ll need header extenders.
I’ve ordered a new pisugar + and zero w to make sure it is not a hardware issue.
Thanks. I suspect that a reboot (or shutdown) does not do a POR (power on reset) on the display. To investigate, run sudo shutdown and then measure the voltages on the 3V3 and 5V of the display. The GPIO connector provides these pins.
When running without the Sugar, have you tried running an example program multiple times without a reboot inbetween? I am asking this since the driver should put the display into power-off mode after a refresh. It should not need a POR. But currently this seems to be the only difference there is between unplugging the battery and a mere reboot.
I’'ll try and measure those 3v3 and 5v points later.
When you mean run the stripes.py example, then a hello_world.py example? Then Yes. When running without the Sugar I can indeed run the program multiple times (without rebooting) with no problem. Also after a sudo reboot, everything keeps working flawless.
However, when I turn the PiSugar (and therefor also the Pi) of using the off-button on the Sugar, and then turn it on, the examples also don’t work.
Everything really only works when I had a short battery disconnect, or run the system without the PiSugar.
This keeps me scratching my head. So we know by now that POR makes a difference for the Sugar, but not for the display+Pi.
Another thing to try: there is a file inky/eeprom.py which just uses I2C to read the eeprom of the display. You could try this in your Sugar setup vs display+Pi. This would tell us that at least I2C is working.