Unicorn hat only works once


#1

I am using the unicorn hat (8x8 one) with a raspberry pi running Retropie 4.2. I understand this is an experimental OS for the unicorn.

My question is this: why does the unicorn hat only scroll through once and when the script runs again I get random flashing lights all over?

I guess I am also looking for a script (either bash or python) that will clear the unicorn hat and reset it.

Thanks for any help,
DM123


#2

Presumably because audio is still enabled. You have to totally disable onboard audio in order for Unicorn HAT to work correctly. It doesn’t matter if the audio is routed out through the HDMI or Analogue, the audio subsystem runs on the GPU and will take over the hardware needed for Unicorn HAT.

In /boot/config.txt you’ll either need to add dtparam=audio=off to the bottom, or find and comment-out (put a # in front of) the line dtparam=audio=on

There are ways to wire the Unicorn HAT to different pins on the Pi, and use alternate hardware for driving it, to get around this problem.


#3

@gadgetoid
sorry for the late response.
I will keep this in mind when tinkering with retropie