Help Driving 24x24 RGB LED matrix

Other Hardware LEDs and Multiplexing
1

Hi all,
Please forgive any noobness, as this is my first post on this board.

I have been given a 24x24 P10 RGB LED Matrix, and for the life of me I can't figure out how to drive it.
It is similar to the smartmatrix panels and the adafruit panels that I've seen around the net. I have attempted to use the adafruit supplied libraries, but they don't work.

It has a 20 pin connector (as opposed to the 16 pin connector on the adafruit panels), 9 of which are earth connections. I believe I've also figured out which pin needs the CLK signal from trial an error using the adafruit library.

It has the following components (other than RGB LEDs):
1x STMicro MCU (http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00226640.pdf)

2x Octal Bus transceivers (http://www.nxp.com/documents/data_sheet/74HC_HCT245.pdf)

1x Quad Buffer line driver (http://www.nxp.com/documents/data_sheet/74HC_HCT125.pdf)

1x Dual retriggerable monostable multivibrator (http://www.nxp.com/documents/data_sheet/74HC_HCT123.pdf)

1x 3-to-8 line decoder/demultiplexer (http://www.nxp.com/documents/data_sheet/74HC_HCT138.pdf)

1x Dual 4-bit binary ripple counter (http://www.nxp.com/documents/data_sheet/74HC_HCT393.pdf)

12x DUAL P-CHANNEL ENHANCEMENT MODE FETs (http://www.diodes.com/datasheets/ds31420.pdf)

18x 16channel constant current LED drivers (JXI5020 Datasheet PDF - Datasheet4U.com) sorry couldn't find this in english.

Now from this I can gather that:
The board is split up into 6 segments of 8 x 12 LEDs, with each set of 3 LED drivers driving 2 rows of 8 LEDs (RGB) at a time, and multiplexing to drive the other parts of the segment over time.

How should I go about figuring out how to drive this thing? I can't even find anyone else on the internet that has these panels!!! I've attached a picture of the back of the panel in case that can help anyone?

Thanks!!
Daniel.

IMG_20150604_193952.jpg
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2

I am sorry but without a schematic of the circuit you don't stand a chance. Drawing a schematic of such a large PCB is a bit daunting, error prone and very time consuming.

3

Really?

4

Hi, I suspect even a schematic won't tell you everything you need to know, because you don't know what program that mcu is running.

You say you managed to figure out whick is the clock line. How did you do that and what does it enable you to display, if anything?

Paul

5

Hi Paul,

thanks for your interest!

I figured once I saw the MCU that there would be a whole lot of stuff going on in the background that would be incredibly difficult to decipher.

As for the figuring out the clock line, I chucked the adafruit library example for their rgb pixel boards onto my UNO, and started randomly plugging wires into lines on the board. I could get it to light up and do a few little bits n bobs. I managed to get all the LEDs to shine a dimmish white with only 3 wires connected (along with some other funky combinations of colours with different wires in different places). But anytime I took the clock signal from the arduino away from pin 12 (in my own pin numbering system) all the LEDs would go blank. And none of the other arduino signals plugged into that pin made the board light up, so I figured it was the clock line... I was only using a sketch to 'turn the 1,1 pixel (top left) on to full green' based again on the adafruit library.

6

So you have fed random data into it randomly and determined that it will only "hold" display whilst it is clocked.

That sounds very much as if it is designed to display some sort of (digital format) video.

7

I think your best chance may be to question whoever gave you the display, where they got it, and follow that chain back until you find someone who knows something about it. As you have failed to find anything about it by searching the web, it may be something manufactured for a particular customer to their own design and not sold to the public.