Inky Phat on a Pi 3


I get terrible display quality when I try to use my new red Inky on a Pi 3 but it’s OK on a Pi zero W.

Is the library doing some loop based timing somewhere?

As a new user I can only post one image so here is the Pi 3 display:

Edit: I should point out that I’m using the same SD card and display for both tests and simply swapping the Pi out from between them.


Cripes! That’s awful. There are no timing based loops- the update cycles are all running directly on the Inky pHAT. I wonder if it’s something to do with temperature? I can’t think of anything else that might be causing it- except perhaps a power shortage?


Don’t think it’s temperature. I literally shut down the Pi 3, swapped the display, SD card and power to the Pi zero and powered it up to get this improved image:

Swapping back to the Pi 3 gives the poor image again. No time to heat up or cool down and same power on both.


Oops. Wrong image. I got that on the Pi 3 by telling it I had a yellow display. Still bad, but differently bad.

This is the Pi Zero image:


What power supply are you using? I don’t recognise that connector.


Just a standard 5V 2A USB power supply with the usual USB cable attached.

You have, however, correctly identified the problem though.

Switching to a 2.5A iPad power supply completely resolved the issue and the quality is better than ever.

I did notice that the initial black and white image came out fine and it was only when the red overlay occured the problems occured.

Possibly that 8mA is a bit of an understatement and it actually spikes a lot higher when painting the red.