Unicornhathd is not lighting up at all - raspi 3B+

Support
1

I have a raspberry PI 3B+ and ordered a unicorn hat HD from Adafruit. I attached it but could see no lighting. I tried upgrading to the latest version of bullseye as well. HAT is tightly fixed to the Pi. No short seen as I also tried putting in some insulation between heatsink and the underside of the unicorn hat HD. SPI is enabled already and I don’t get any errors when I run any of the examples under the unicornhathd lib ( I double-checked that I installed the correct module - unicornhathd). Out of ideas at this point and I feel like I got a defective piece. Any thing else I should try?

2

Hello. What is the output of:

sudo i2cdetect -y 1

I’d also suggest contacting Pimoroni’s support, deets here.

3

Had to install i2cdetect but now I see the below. No change on LEDs.

 sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Thanks for the deets. Will reach out there as well. I wasn’t sure as that page says to create a post first on the support forum.

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4

Just a FYI post, i2cdetect scans the i2c bus for devices. The i2c address used by the device will be shown in the scan results.
The Unicorn Hat HD uses SPI, not i2c. That scan is normal assuming you don’t have anything else connected to the GPIO header.
I’m not aware of an equivalent tool for SPI, likely because of the way that bus works.

Unicorn HAT HD at Raspberry Pi GPIO Pinout

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5

Cool, hope you get it sorted.

Indeed Alpha, you are quite correct. But, if there were something showing on the i2cdetect, it could be indicative. I probably should have asked about uname -a too. Ho hum, I often try to do too many things at once. I’m male, therefore unable to multi task.

6

Yeah, it kind of depends on what Hat or pHat it is. Some use i2c, some SPI, and some both. Usually sensors are on i2c and the displays on SPI. There are a few exceptions, so checking the pinout helps, of having a good read of the product page.