Does the Unicorn Hat require an external power supply?

Hello, My question is does the Unicorn Hat require an external power supply to run? I have a 5V DC with 2.1 A output adapter connected to the Raspberry Pi. Is that enough or does it need more of a power output to run?

it takes power from the GPIO header on the Pi. You’ll be fine with a 2A PSU.

Are you sure?

20mA per LED colour gives me 60mA per LED. 64x60mA equals more than 3.6A

Yes, I’m sure… you don’t want to run the LEDs full beam. In fact the last soul who tried that ended up with a bunch of components desoldering themselves from the board ;-)

IMO this limitation should be mentioned/described somewhere (especially since heat dissipation is an issue as well). Probably not a critical issue for the reason you gave but still something to keep in mind.

The most recent library limits the brightness to 50%, so unless you modify it then there’s simply no risk of running into either power or heat dissipation issue.

Of course this is a cap in the software we provide, if writing your own then you’d have to consider what is sane or not sane to do.

Hi RogueM,
I’ve noticed my LEDs are nowhere near as bright as they used to be before an update. How do I go about modifying the library so I can get back to the original brightness?
Thank you!

First of all, verify that your scripts don’t include a brightness setting… if so remove it or raise it (max value 1.0).

If that’s still not enough for you then have a look at the brightness method in, it should be self-explanatory… however there is a reason we now reign the brightness back, use common sense, i.e don’t look to the LEDs directly, use a diffuser, etc… eye injuries is not a matter to take lightly!

Thanks RogueM! I edited the as you suggested–it now works like it used to.