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hzeller / rpi-rgb-led-matrix

Controlling up to three chains of 64x64, 32x32, 16x32 or similar RGB LED displays using Raspberry Pi GPIO
GNU General Public License v2.0
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Horizontal flickering on panels #977

Open amantalion opened 4 years ago

amantalion commented 4 years ago

Hi,

Has anyone encountered horizontal flickering (literally horizontal lines going across the screen) on a chain of panels every 20 seconds or so? If so, then how did you resolve the problem?

I have 6 x P5 64x32 panels with 1/8 scan rate and ICN2037. I use —led-multiplexing=1 and a U-mapper.

Thank you.

hzeller commented 4 years ago

did you disable 1-wire ?

hzeller commented 4 years ago

if you have these panels on one chain, you might also max out cpu and the kernel might throttle. If you can, put the panels on parallel chains.

amantalion commented 4 years ago

Hi @hzeller, thank you so much for the quick reply. I checked and it looked like 1-wire was disabled. I tried to do a clean install (of Raspbian Lite) and now I have noise instead of the desired pattern.

I am running the following command: sudo examples-api-use/demo -D0 --led-rows=32 --led-cols=64 --led-multiplexing=1 and getting the following noise (I use the Electrodragon hat for the Raspberry Pi). IMG_5531

Have you encountered this issue before by any chance?

hzeller commented 4 years ago

This looks like that there is something else competing for the GPIO ports. Check out the troubleshooting section in the README. Also, if the GND is not connected between panel and raspberry pi results in something like this, but given that you are using a level-shifter board, that is unlikely. Often the panels are slower than the speed of the Pi, so adding some --led-slowdown-gpio can help.

hzeller commented 4 years ago

Did you get it to work ? If so: what was the culprit ?

amantalion commented 4 years ago

It turns out that the second problem was due to the fact that I accidentally used RPi 4, instead of RPi 3. I fixed the issue with random patterns on RPi 4 by using ‘led-slowdown-gpio=2’. However, I encountered horizontal ghosting which I couldn’t fix using troubleshooting guidelines. Therefore, I went back to RPi 3 and it completely fixed the second problem with random patterns and horizontal ghosting.

I am not sure yet, if the fresh install fixed the horizontal flickering problems. I will test/troubleshoot today and report back (will reopen the issue).

amantalion commented 4 years ago

Went through the debugging steps and still getting some horizontal flickering.

However, if I use 2 parallel chains of 3 panels instead of one long chain of 6 panels (with a U-Mapper), I don't see flickering when running examples-api-use/demos (tested it with -D 4). I still have the same problem when showing a custom image using utils/led-image-viewer (tested it with both configurations: 2 short chains and one long chain).

ZuzooVn commented 3 years ago

@amantalion Did you find the solution?