Rpi-rgb-led-matrix with Raspberry PI4 with tutorial : command not found

[SebastienLBA]

Hello, I am a real beginner with Raspberry Pi and all this "coding" thing ! I am mostly an electrical engineer and I used to program PLC with functional block. But, for a project, I need to drive a matrix of leds, which is impossible with the PLC I am currently using so I thought about using a Raspberry Pi. And here I am ! I bought a Raspberry Pi4 and a matrix of leds and I try to follow this tutorial for beginner : https://learn.adafruit.com/connecting-a-16x32-rgb-led-matrix-panel-to-a-raspberry-pi/overview

I think I did everything well until the step "testing" : https://learn.adafruit.com/connecting-a-16x32-rgb-led-matrix-panel-to-a-raspberry-pi/testing

But I must be missing something because, after the final command sudo ./led-matrix, it writes the following message : sudo ./led-matrix : command not found Here is the full printscreen :

I don't know what I am missing, certainly something dumb but I I think it may be about the file "Makefile" because I do not find the line that I have to uncomment : DEFINES+=-DRGB_CLASSIC_PINOUT

Anyway, I am calling for your help because I don not have a clue and I try to figure thie out for 2 weeks now...

Thanks a lot,

Seb

[davemaster]

FIRST, you need more knowledge about linux raspbian environment: use "ls" command to see the files (as dir in DOS)

SECOND, the adafruit tutorial about how to testing LED panel, is very OLD, the rpi-rgb-led-matrix is continously updated; the command/program/executable led-matrix is not included anymore.

tHEN use: sudo ./demo

[hzeller]

+1 What David said. And the demo is in examples-api-use. The relevant section in the readme is https://github.com/hzeller/rpi-rgb-led-matrix#lets-do-it

@SebastienLBA Please also write the Adafruit people that they should update their tutorial about my library.

[SebastienLBA]

Thanks a lot for your quick answers. I will try with this new tutorial.

[SebastienLBA]

Hello, It's me again, So I followed the the readme in https://github.com/hzeller/rpi-rgb-led-matrix#lets-do-it and almost everything went well. Everything seems to be well connected but I struggle to have a good rotating square with the demo -D0 (pictures below). There are plenty of other leds ON and kind of ghosting.

I am using the following led-matrix : https://shop.mchobby.be/fr/leds/1318-matrice-led-rgb-16x32-empattement-5mm-3232100013186.html There is not much details in the datasheet.

Here is my standard command : sudo examples-api-use/demo -D0 --led-rows=16 -- led-cols=32 --led-chain=1 --led-parallel=1 --led-no-hardware-pulse

I tried to play with every parameters such as :

• --led-gpio-making
• --led-multiplexing
• --ledpixel-mapper
• --led-pwm-bits
• --led-scan-mode
• --led-pwm-dither-bits
• --led-limit-refresh

Nothing works fine, the best parameters are always the parameters by default. Do you know what could possibly be the problem? Thanks for your help,

Seb

Here are the pictures :

[hzeller]

Need more detail :) For instance, did you go through the troubleshooting section and made sure to follow all steps there ?

Did you wire it directly to the Pi or used digital level converters ? Not all panels will work with 3.3V logic level and if so it might be a hit and miss if wired directly.

If you wired it manually, it is particularly important that the wires between the Pi and the panel are short.

Did you double-check that GND is well connected between Pi and Panel ? Where is the power coming to the Matrix coming from ? It needs to be a good power supply that can deal with short spikes. Make sure the power cable from the power supply to the Panel is direct and as short as possible. Consider adding a low ESR capacitor close to the panel.

The most influential parameter in this scenario will probably be --led-slowdown-gpio. The Pi4 is fast, and panels typically can't keep upt. Start with --led-slowdown-gpio=4 to see and reduce maybe to 3 if you panel can keep up.

Don't use --led-no-hardware-pulse; it is only really meant to work-around situations where it can't be used, but it will provide less stable color output.

[SebastienLBA]

Thank you very much !!!! It was the only parameter I did not try! It works very well with --led-slowdown-gpio=2 !

For all your others wuestions, Everything is OK, I have a good power supply, with short wires. And I wired it myself but with good and short wires :-)

Thanks you, now that I have the basement, I will try to have some fun with it !

[jaygarcia]

@SebastienLBA please close out this issue when you have a moment :).

[koplinm]

I've run into the same issue, this thread is helpful. The program I am trying to run is calling demo. Is there something similar to demo that does not require the manual ctrl C reset for new display content?