Cannot get panel to display anything

1

I have the following componments:

RPi Zero W

Electrodragon Active-3 board (Latest rev - v3?)

I have configured the jumpers for the E line on pin 8 (Green lines in pic below):

image
image736×493 146 KB

A 128x64 ABCDE panel

image
image1920×1440 779 KB

I cannot seem to get anything at all to display on the panel using the demo app

I have tried loads of combinations of command-line parameters, but nothing.

I am powering it via a bench PSU, so I can see the current draw - I am providing power to the Pi via the active-3 board.

With just the pi and active-3 powered up, I see 0.13A drawn

If I plug in the Hub75-E connector to the panel, I see 0.25A drawn

If I then power up the panel, it goes up to 0.35A

Then, when I run a demo (eg ./demo -D 0 --led-rows=64 --led-cols=128 --led-row-addr-type=4), it goes up to 0.43A

Any thoughts as to what I could be doing wrong?

Power requirements in docs. Inaccurate?
2

  1. zoom on the chips

  2. check them against GitHub - hzeller/rpi-rgb-led-matrix: Controlling up to three chains of 64x64, 32x32, 16x32 or similar RGB LED displays using Raspberry Pi GPIO and Led_drivers · board707/DMD_STM32 Wiki · GitHub

Anything PWM will not work with this lib as of today..

3

it looks like a ABC panel.
I don’t have a datasheet for the MW5566 line driver chip, but according to indirect references on Chinese websites, it’s a shift-register (or 595) type multiplexer.
If so, you need using the option --led-row-addr-type=5 with it.
The main led driver FM6124, as far I know, doesn’t require any specific settings to work.

5

it can work with another lib if it supports PWM, this lib does not as of today, which is the answer for the original poster.
That said, if adafruit has a PWM lib that works, that may be helpful to @board707

7

The vendor said it was ABCDE, and pin 8 on the Hub75 connector is marked E

I tried --led-row-addr-type=5and got an image. Thankyou!

panel first image

Now I just gotta work out how to get rid of the corruption.

Edit: –led-slowdown-gpio=2 did it

8

The pin markings on connector don’t matter much, as silkscreen on the panel is ​​often printed without regard for a specific pinout.
Your panel only uses ABC pins. You can disconnect the D and E pins and check—nothing should change.

9

So on the Electrodragon board, removing the jumpers that set up the E pin should suffice?

Otherwise, disconnecting the pins would be tricky

10

sorry, I know nothing about this board.

11

Well I disconnected the CHAIN-SETUP jumpers on the Electrodragon board (Configuring the E pin), and indeed nothing changed. @marcmerlin can you advise? Does this mean the board is ABC?

Here are some close-ups of the chips - about as good as I can do without a macro lens methinks

The panel is mostly comprised of these

IMG_20251208_141517
IMG_20251208_1415171920×2560 574 KB

One column of these on each side

IMG_20251208_141702
IMG_20251208_1417021920×2560 360 KB

There are only three of these ones, in the middle.

IMG_20251208_142109
IMG_20251208_1421091920×2560 327 KB

12

Please look at rpi-rgb-led-matrix/adapter at master · hzeller/rpi-rgb-led-matrix · GitHub . ED3 is the best board for this lib, and that board is also the reason to use this lib; 3 parallel outputs and 3 times the refresh rate or resolution than any other lib that is single output

13

right, I was going to say your video clearly showed something that is fixed by a higher slowdown. Glad you found it

14

Yeah, I have it working, but I am seeing an occaisional slight dimming. Not a flicker (As in breifly no image), just a dimming. It’s hard to describe, it’s like you are blinking when you aren’t.

It appears to be CPU related - if I have htop running while the app is running, it’s even more frequent.

It’s a pi zero W 2

This is with my C# app calling led-image-viewer though (And it also has a web REST server running), so I suspect it’s more to do with that.

Even just with the led-image-viewer run on it’s own from the command-line, core #3 is pegged at 100% when showing an animation - is this to be expected?

I get ~370hz with the following command-line:
`led-image-viewer --led-rows=64 --led-cols=128 --led-row-addr-type=5 --led-slowdown-gpio=2 --led-parallel=2 --led-show-refresh --led-pwm-dither-bits=1 --led-pwm-lsb-nanoseconds=50 --led-pwm-bits=7 polygonmorph.stream`

If I use this, I only get ~100hz, but core #3 is at 75%
`../led-image-viewer --led-rows=64 --led-cols=128 --led-row-addr-type=5 --led-slowdown-gpio=2 --led-parallel=2 --led-show-refresh polygonmorph.stream`

Any of the parameters –led-pwm-dither-bits=1 --led-pwm-lsb-nanoseconds=50 --led-pwm-bits=7 all put CPU at 100%

15

How many panels you have in total? I far I can understand, the “parallel” mode needs a multiple panels to be useful.

16

I have 2x 128x64 panels (So 128x128 in total)

However, both of them only have an input, so I cannot chain them

17

Thanks, understood it

18

Yeah, I get this at times too, it’s a hard to problem to pin down, no one has found a full fix for it unfortunately.
The more bright and white you go, the more it happens, and it’s not just because of power.
Yes it’s normal to have one core be 100%, it’s to make sure it outputs as fast as GPIO allows with as little flickering as possible.