Inky Phat on a Pi 3


#1

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.


#2

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?


#3

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.


#4

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:


#5

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


#6

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.