# Cannot get panel to display anything **URL:** \ **Category:** Uncategorized\ **Created:** [December 7, 2025, 9:34pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156 "2025-12-07T21:34:43Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 7, 2025, 9:34pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/1 "2025-12-07T21:34:43Z")
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](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/60bf8f3391bb3678cbceebd0c8c527342cf901fe.jpeg) A 128x64 ABCDE panel ![image](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/22d3a93ad8ef35b311a2aadb77bfadb21eb33dc5.jpeg) 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? ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [December 7, 2025, 10:03pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/2 "2025-12-07T22:03:34Z")
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](https://github.com/hzeller/rpi-rgb-led-matrix?tab=readme-ov-file#panels-supported) and [Led\_drivers · board707/DMD\_STM32 Wiki · GitHub](https://github.com/board707/DMD_STM32/wiki/Led_drivers) Anything PWM will not work with this lib as of today.. ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [December 8, 2025, 12:10am UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/3 "2025-12-08T00:10:12Z")
> [@evilC](#): > > A 128x64 ABCDE panel 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. ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [December 8, 2025, 6:43am UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/5 "2025-12-08T06:43:48Z")
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 ---
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 8, 2025, 12:15pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/7 "2025-12-08T12:15:30Z")
The vendor said it was ABCDE, and pin 8 on the Hub75 connector is marked E I tried `--led-row-addr-type=5`and got an image. Thankyou! ![panel first image](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/a48ffdf6c8b8ceac89489f965a532745a0613815.gif) Now I just gotta work out how to get rid of the corruption. Edit: `–led-slowdown-gpio=2` did it ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [December 8, 2025, 1:31pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/8 "2025-12-08T13:31:13Z")
> [@evilC](#): > > pin 8 on the Hub75 connector is marked E 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. ---
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 8, 2025, 1:33pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/9 "2025-12-08T13:33:39Z")
So on the Electrodragon board, removing the jumpers that set up the E pin should suffice? Otherwise, disconnecting the pins would be tricky ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [December 8, 2025, 1:51pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/10 "2025-12-08T13:51:03Z")
> [@evilC](#): > > on the Electrodragon board sorry, I know nothing about this board. ---
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 8, 2025, 2:24pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/11 "2025-12-08T14:24:17Z")
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](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/66e0a4366b32a9d96fafc9b0fa8f122a60036a1d.jpeg) One column of these on each side ![IMG_20251208_141702](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/1051824e6d9b71b6004b395c904f3b4f9da87532.jpeg) There are only three of these ones, in the middle. ![IMG_20251208_142109](https://global.discourse-cdn.com/free1/uploads/rpi_rgb_led_matrix/original/1X/14626eccb663bd0574b2a4648bcc1a2aed099bc2.jpeg) ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [December 15, 2025, 6:54am UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/12 "2025-12-15T06:54:15Z")
Please look at [rpi-rgb-led-matrix/adapter at master · hzeller/rpi-rgb-led-matrix · GitHub](https://github.com/hzeller/rpi-rgb-led-matrix/tree/master/adapter) . 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 ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [December 15, 2025, 6:54am UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/13 "2025-12-15T06:54:54Z")
right, I was going to say your video clearly showed something that is fixed by a higher slowdown. Glad you found it ---
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 15, 2025, 2:40pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/14 "2025-12-15T14:40:27Z")
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% ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [December 15, 2025, 6:35pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/15 "2025-12-15T18:35:02Z")
> [@evilC](#): > > –led-parallel=2 How many panels you have in total? I far I can understand, the “parallel” mode needs a multiple panels to be useful. ---
**Author:** ![evilC](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/evilc/32/711_2.png) [@evilC](https://rpi-rgb-led-matrix.discourse.group/u/evilC)\ **Post date:** [December 15, 2025, 6:56pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/16 "2025-12-15T18:56:44Z")
I have 2x 128x64 panels (So 128x128 in total) However, both of them only have an input, so I cannot chain them ---
**Author:** ![board707](https://avatars.discourse-cdn.com/v4/letter/b/bc79bd/32.png) [@board707](https://rpi-rgb-led-matrix.discourse.group/u/board707)\ **Post date:** [December 15, 2025, 7:10pm UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/17 "2025-12-15T19:10:54Z")
Thanks, understood it ---
**Author:** ![marcmerlin](https://yyz2.discourse-cdn.com/free1/user_avatar/rpi-rgb-led-matrix.discourse.group/marcmerlin/32/40_2.png) [@marcmerlin](https://rpi-rgb-led-matrix.discourse.group/u/marcmerlin)\ **Post date:** [December 17, 2025, 7:23am UTC](https://rpi-rgb-led-matrix.discourse.group/t/cannot-get-panel-to-display-anything/1156/18 "2025-12-17T07:23:09Z")
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.