I didn’t see a link to a schematic for the Inky Impression 4 on the product page. The question I wanted to answer by looking at it was this: does it need a 5V input?
Experiments with a non-Pi board that can’t easily supply 5V suggests that it works without, but it would be good to know if it should be supplied.
Does that cover the 4" version as well? The schematic for the 5.7" version appears to show that the 5V pin on the connector is used.
Looking at a datasheet for the display controller, I can’t see where 5V would be used. It seems to only require voltages from 2.3V to 3.6V.
That I don’t know? All that’s listed is what I linked too.
Raspberry Pi GPIO Pinout
There is a link on the shop page to contact Pimoroni tech support via e-mail.
They should be able to get you a schematic.
Contact Us for Raspberry Pi Technical Support - Pimoroni
Thanks! I should probably have started with the technical support form but I thought others might have already gone down that route.
An update from Pimoroni’s support: the Inky Impression 4" doesn’t need 5V, only 3.3V.
This makes it compatible with a lot of development boards. I’m currently using it with an STM32 MicroMod processor board attached to a carrier board and it works fine. You can get some really nice looking results with this display.