Cannot get panel to display anything

[evilC]

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):

A 128x64 ABCDE panel

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?

[marcmerlin]

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..

[board707]

@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.

[deadlift89]

@marcmerlin

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

Can confirm adafruit-hat-pwm works I am using this today

[marcmerlin]

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

[deadlift89]

My apologies if you’ve had to repeat this before, or I’m lacking context from issue threads - but that pin modification between #18 and #4 no longer works?

I’ve been using this library since 2021 and all this time I’ve been telling myself a lie that I was pulse width modulating

If so we should update this section readme - improving flicker

[evilC]

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!

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

Edit: –led-slowdown-gpio=2 did it

[board707]

@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.

[evilC]

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

Otherwise, disconnecting the pins would be tricky

[board707]

@evilC

on the Electrodragon board

sorry, I know nothing about this board.

[evilC]

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

One column of these on each side

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