Display HAT Mini not showing anything


I connected my Display HAT Mini to my Raspberry Pi 400 with a 40-pin cable.
I managed to install https://github.com/pimoroni/displayhatmini-python and https://github.com/pimoroni/st7789-python successfully, I am trying the examples.

However the screen doesn’t show anything. No leds are on.
When I run an example script, the screen lights up a bit, that’s all.

What could be wrong?

Male to female ribbon cable?

If yes, Double check your ribbon cable orientation.
Make sure pin 1 on the Pi 400 goes to pin 1 on the display hat mini.

If no, How did you swap genders on one end of the ribbon cable?

Male to female, yes.

I double checked orientation, I believe it’s correct: red marked side of ribbon is at pin1 on the Raspberry Pi 400 side and enters the DHatMini near the I2C chip.

I wonder, is the led supposed to be on?
How could I diagnose correct connection?

It’s connected like this:

That looks correct to me, plus the backlight is on.
SPI enabled?
Any error messages when running the examples?

I don’t own a display pack, so I can’t advise on the LED. They light up dimly on the PICO Display packs. It likely depends on how its wired and if its common cathode or common anode.

No errors when I run the examples, and SPI is enabled.
I also rebooted the system.

I’m stuck atm.

Are you running the Display Hat examples or the ST7789 examples?
The ST7789 examples likely won’t work without some edits.

I tried both.
What specific edits would you recommend for the ST7789 examples?

You need to match the pins the Display Pack is using.
Width 320, Height 240, SPI0, CE1, DC 9, Backlight 13, etc.
Display HAT Mini at Raspberry Pi GPIO Pinout

I see, thank you.
Basically this should work: st7789-python/320x240.py at master · pimoroni/st7789-python · GitHub

But it doesn’t.

I am running a system update now, will see if it makes any difference.

That looks correct, so should work. You may have to plug it directly into the back of the Pi 400. Just to make sure its not an issue with the ribbon cable?

I have run single and dual setups using the ST7789 240x240 LCD’s and the ST7735 160x80 LCD’s, on my Pi 400. Breakout garden setups.

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In the meantime I tested a different setup as well with a Pi 400 Expansion board, and a different ribbon. The board shows diagnosis leds, which helps, and I also plugged in a ScrollHAT Mini, which works.

But the Display HAT’s screen is the same, all blank, with only backlight on.
So I am about to return it, I guess it’s simply faulty.

Sounds like it to me. It happens every now and then. So far for me its been few and far between.
The scroll hat mini uses i2c, not SPI, just FYI.

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