Unicorn HAT - No Output


Wish I had read the what works and what doesn’t with the Pi 2 before ordering mine with a Unicorn HAT :(. I hope it is all solvable in software otherwise I’ll be stuck with an unusable Unicorn.


Don’t worry, it’s solvable. Getting it up and running has been one of my top priorities, since it’s something I can directly affect and don’t have to rely on anyone else to fix.

Unfortunately, between the lack of documentation and lack of understanding it’s proving to be somewhat tricky!

To top it all off, I had a dream last night that it was all fixed and working fine. Dream logic never works in reality :(


Agreed! New Pi and HAT. Ah well. Will get there in the end.


I too spent most of last night trying to figure out why my Unicorn HAT wasn’t lighting up (connected to my Pi 2). I thought it was something I’d overlooked.

I should have just come here first!

I’m hoping to knock up a sound/music visualiser program for it so really looking forward to the Pi 2 compatibility update!


Me too (bought a new Pi2, Unicorn HAT and a diffusion layer for the Ninja PiBow case that doesn’t fit).
Glad to hear Pi2/Unicorn issue should be fixable.

I just want add my appreciation for anyone who is working on this issue. Thanks.



Small update: Jon’s been tinkering with UnicornHAT this weekend, too, it’s definitely not a fatal hardware difference, but rather some new weirdness with memory caching. It’s so tantalisingly close to working that it’s driving us all completely bonkers!

We’re working on pinning down exactly what’s going on, so we can upstream a fix or work around it. Stay tuned!


Best of luck. Keep us updated!


Quiet in here. Heads down, working on that tricky Unicorn HAT!


Just to tie up a potential loose end.
It looks like there has been some progress, a hacked version is available:
Link to Pimoroni Forum thread
Hopefully a fully finished and polished version will follow soon.

Thanks all!


Just to chime in- we now consider this the “release” version, it’s available in pip

sudo pip install unicornhat --upgrade

And is pretty well tested now.

We’ve got some more changes coming to make it just a liiitttle bit better ( in terms of gamma correction ), but otherwise it’s case closed. Unicorn HAT is pooping rainbows like a champ again!

For anyone who’s curious, the code is based upon the rpi_ws281x, which Richard Hirst whipped up the Pi 2 fixes for- https://github.com/richardghirst/rpi_ws281x - he deserves praise and adoration!


Richard Hirst - please accept our praise and adoration!
IoI .o. Iol .o. Iol .o. Iol .o. Iol .o. Iol .o. Iol


I read that as “lol” first, then … I saw what you did there! Will never unsee.


Marvellous!! Great work. Haven’t had to time to try it out yet but I’m looking forward to making myself blind :D


Working well here… Ah my eyes !!!




I just got my Unicorn HAT today. I freshly installed the latest Raspbian version and used this command to install the drivers:

curl -sS get.pimoroni.com/unicornhat | bash

When I try the demos, nothing happens. There is no error and no LED is visible. I am using a 5V/2A power supply.

Any ideas? :/



Do you have another Pi to try it on? I don’t have a Unicorn HAT with me to try and reproduce your problem.

Are you running any audio software, since that conflicts with the bizarre way the Unicorn HAT software works.


Thanks for your fast reply.

Yes, I have a RPiB+ here. I reinstalled Raspbian and installed the drivers with the same command like the RPi2 on it, but I got the same result. :( Nothing happens when I try the demos. The demos are working, I don’t get any errors. No LED is working.

Maybe the cute Unicorn (board) is broken? :(


I think it’s possible. There’s one way to find out for sure, drop us a support email with your order number/address and the shop crew should be able to sort you out with a replacement.

Sorry you got a dud :(


Okay, I got this form Amazon and I will send it back. I just created the ticket.

With a bit of luck I will receive my PiGlow today. Maybe I can play around with it. :D

Thanks for your help.


No problem!

Good luck with the PiGlow. I like that people have seen the PiGlow format as a challenge and done all sorts of interesting things with it.