Unicorn Phat with loose contact?


I recently bought an Unicorn pHat on Amazon. I attached on my Raspberry Pi 3, but when I start the rainbow.py script nothing happens. When I run detect.py it says that my pHat is detectable, so I removed the pHat and while removing I had a short flashing of light. I pushed a little a bit on the pHat and got all lights on. After a while of try and error I managed to get the rainbow lights. Is it possible that my pHat has loose contact? Or do I miss something fundamental?


Could you possibly post a picture of your pHAT/soldering?


I did not solder it to the board. Is it necessary?



Absolutely necessary. You need to solder the (supplied) 40-pin header onto the Unicorn HAT.

The GPIO pins are square, and the holes in the PCB are round. It’s a case of literally putting a square peg into a round hole- there’s very, very little contact between the two, not nearly enough for a reliable electrical connection.

While you can kind-of make it work by lifting the pHAT gently so it contacts the GPIO pins better, it’s a much better solution to solder it.


Thanks for your help.
Hopefully I did not disgrace myself too much.


Haha, just browse the support forums for a bit, you’ll feel much better :)

I’ve definitely used stuff unsoldered before, and levered it up against the pins for a connection. That’s the only reason I know that trick works :D

… the thing I was doing it with- a Sparkfun USB Serial breakout -then suddenly stopped working. I thought I’d broken it with my trick, so I bit the bullet and ordered a replacement. Turned out to be a faulty USB cable =/