Pi-Top with unicorn hat HD


#1

Hello,
I received my pi-top yesterday and all seems to be working fine, i am however having a few issues with the unicron hat HD, flickering the screen whenever i use it. (https://twitter.com/ajalexsmith/status/887392548800647168)
i was wondering if anyone else had had any issues? my thoughts are its a power related issue but i’m not too sure

many thanks

Alex


#2

Update: i have been playing around and it seems to be changing the unicornhathd brightness does the same to the pi-top. is there any way to change this?


#3

Firstly: I completely agree with Guru there, MORE BLINKY LIGHTS! However, you do need a screen to first program the blinky lights, which does pose a problem…

To that end, what power supply are you using (particularly the ampage)? I presume some sort of official supply for the Pi-top itself? The Raspberry Pi 3 uses a 2 amp power supply, so I’m guessing the Pi-top would need much more power when lighting both the screen and the Unicorn Hat at full brightness.


#4

Sadly after buying the pi-top I can’t afford any more blinky lights 😂😂I am running the pi off the lipo battery. I’m not sure specifically on the power output but the charging cable has an output of 18 volts at 3A


#5

What is the LIPO battery connected to? And how does that power the Pi?


#6

it’s all internal through the pi-top circuitry and power management board


#7

Ok, thanks. Doah, should just googled it. My bad. I see a cable connected to the GPIO, that appears to go to the other board. What does that do? If it used some of the GPIO pins etc, there may be a conflict with that and the unicorn HD hat.


#8

That handles the screen etc. This is what I was thinking, if only the pi-top circuitry was on PinOut! I have set up a support ticket with pi-top so should hopefully get a bit more information


#9

How are you hooking the unicorn hat and the Pi Top display cable up at the same time? Or are you?


#10

Try driving the Unicorn HAT HD to black, instead of reducing the brightness, IE: set all pixels to 0,0,0 and update it constantly. If the screen still flickers then this would indicate a problem other than power. If it doesn’t, then it’s just the power supply. Even at conservative estimates on low brightness, Unicorn HAT HD can easily pull 1A. It’s a hungry, hungry hippo!


#11

I got a reply from pi-top last night saying:
The Unicorn HAT HD and the pi-top HUB are using some of the same SPI communication lines for screen brightness and power monitoring features so this is the cause of the error.
I have informed the hardware team of this instance.
A work around for the moment is to install Raspbian onto your SD card as this will allow you to use the Unicorn HAT HD with the pi-top.
I installed raspbian instead of the pi-top os and it seems to have fixed the issue :)
Many thanks for all your help!