Display-o-tron hat backlight is flickering

I haven’t used my display-o-tron hat for awhile, but I wanted to use it with an enviro-phat I just picked up. It displays fine, but when I run the demo program, the backlight constantly flickers, so it’s distracting to use it. It never used to do this.

I’ve got a pi 3 b+, and downloaded the most recent version of the display-o-tron library. Any ideas why it’s flickering so badly? Everything else seems to work fine.


Could you have some other code running in the background that’s interfering with it? This is usually the source of weirdness like this.

There’s nothing else running but a terminal with the demo.py program. It’s a new, clean install of the OS, and the only libraries I’ve added are the Pimoroni ones.

did you try running one of the other examples

Yes – the flickering happened while running all the examples that included the backlight.

Is the HAT pushed down firmly, and making good contact with the header?

You mention using it with Enviro-pHAT, how is everything wired up?

Yes, I made sure the connections were good and pushed the hat down firmly on the pins.

I tried connecting it first using a pHAT Stack with the Enviro-pHAT. I then turned off the pi, removed the Enviro-pHAT but still used the pHAT Stack, booted back up, ran the demo, and it was still flickering. So I then just connected the display-o-tron directly on the pi, without the pHAT stack. The flickering happened in all 3 cases.