Connecting multiple chains of matrix displays

[Brettucci]

I am extremely new to electronics projects like the one I'm doing with a Raspberry Pi, so I apologize if I do not even know the correct questions to ask. I am trying to connect multiple matrix displays to my Raspberry Pi 4. I have been following the help from the following repo.

https://github.com/hzeller/rpi-rgb-led-matrix

I think I have things hooked up correctly for one chain of displays. I really want to be able to hook up more chains, but have no idea how that is actually done. I've been looking at the following page for some help with how to wire everything.

https://github.com/hzeller/rpi-rgb-led- ... /wiring.md

That wiring page says some things for each chain like the RGB values need to be connected to their own pins on the Pi. Other things like GND, strobe, clock, OE-, A, B, C, D are said to need to be connected to the same pins on the Pi. Am I understanding that correctly? If I have 3 chains, I need to connect the strobe from all 3 to the same pin on the Pi? If so, how do you go about doing that? (Sorry. I really did mean that I was new to electronics)

I have another general question. How should I even find out the correct way to wire the pins to these external devices whether it be a display or a camera? How do I know which pins do what and where they should be hooked up on the Pi? The displays I bought have no apparent documentation included or online from what I can tell. I would have absolutely no clue where to start if it wasn't for that GitHub repository that I mentioned.

I have been a software developer for over a decade and am confident that I can write the code once I have the hardware more figured out. I just really do not know where to start with a lot of this. Thanks for taking the time to read this.

[boyoh]

You are proving my point ,as I have said on the forum before , That you can only wright code for a project if you know how it works
The lack of understanding electronics is holding you back if you if you concentrate to much on coding and ignoring the
hardware side, If you are a software developer you should find basic electronics easy to learn All the basic electronics to learn
you will find on the Web. We don't want to have future were there more software engineers than hardware engineers.

Regards BoyOh

[Brettucci]

So in my post asking for help with learning electronics and hardware, your response is basically "learn more electronics and hardware". The point of my question is that I know so little that I don't even know where to start looking to help me learn. I looked to this forum as one of those "places you will find on the web" as you mentioned.

Not every software developer needs to know the hardware side very in-depth. That's why OSs and the APIs and frameworks they use exist. The hardware is abstracted away on purpose to make software development more efficient. If you're making a Windows application, for example, you really should not need to know how the individual pins on your boards are working. You ideally should not even need to know which specific hardware is in the computer unless you're dealing with some highly specialized software. I literally would never need this in-depth knowledge of hardware in my software development career. I'm attempting to learn this because I'm interested.

Thanks for the response, but it really does not address the question at all.

[boyoh]

You are given the option of setting the GPIO I/P
To a impedance level that the processor can
Respond to. In its high impedance state floating
It will not sink or source a working level signal
This being a logic level 0 low or 1 high, So you
MUST set it to a working impedance level by
Setting the internal resistance 50k or using a
External resister of 10k . If you want it to respond
To a logic 1 high you connect it to the 0v rail
If you want it to respond to a logic 0 low you
Connect it to the 3.3v rail
One point is if you have the pull-up resistor
To low a value this will set the IN/Put impedance
To low , Ok for noise suppression ,but will degrade
The low input signal, ( Impedance = Resistance )
Regards BoyOh

Digest this ,It might give you some idea of what you will want to know ,when interfacing with the Pi

[neilgl]

Welcome to the forums. For ...find out the correct way to wire the pins to these external devices..., usually the device seller/manufacturer will have a specification for the interface, or a data sheet, or examples. A good resource for The pi GPIO is here https://pinout.xyz/. The link to github mentions custom interface boards to all three displays to be attached. Might be worth it?

[Brettucci]

Thank you for the responses. I'm not going to pretend to understand everything that you have suggested, but it definitely gives me specific things to look into and learn about. Thanks! I'll post here if I have any updates on how I approach things.

Of course, any other feedback or help is appreciated if anyone else has any.

[boyoh]

Thank you for the responses. I'm not going to pretend to understand everything that you have suggested, but it definitely gives me specific things to look into and learn about. Thanks! I'll post here if I have any updates on how I approach things.

Of course, any other feedback or help is appreciated if anyone else has any.

From BoyOh
Getting Started in Electronics by Forrest.M.Mims. “One of the best books to start in Electronics” –

You will find this book very good lots of circuits to build and learn from

You will find the Forum very help full, But you must do the research your self The Forum will only point you in the right direction
and NOT designee the project for you.
Regards BoyOh I'm 88yrs and have not finished learning Retired Electrical / Electronics Technician

[FTrevorGowen]

@Brettucci, given that RGB matrix displays require more "work" than "single" colour devices you might find "taking a step back" and try out some of these I2C or SPI interfaced device examples which are somewhat simpler to chain (or, as I call it, cascade):
https://www.cpmspectrepi.uk/raspberry_p ... odule.html
https://www.cpmspectrepi.uk/raspberry_p ... odule.html
Trev.