Well long story short a friend of mine gave me a LED marquee to mess with for his radio club. So far he did research and found that there is no data sheet on the device. Nor could he find an instruction manual so it trickled down to a project for me to try to figure out how it works

So what we do know about it. It accepts input from a standard ps/2 keyboard. It also has a serial port on it. We are hoping as a ultimate goal we can program text strings through the serial for use as a now playing readout for his radio station.

The marquee:
https://img.ourl.ca/rfg/2012-10-20%2021.53.03.jpg

Its control Board:
https://img.ourl.ca/rfg/2012-10-20%2022.26.06.jpg

The Front of an LED panel:
https://img.ourl.ca/rfg/2012-10-20%2022.49.45.jpg

The Back of an LED panel:
https://img.ourl.ca/rfg/2012-10-20%2022.50.17.jpg
(links as they are quite large)


My thoughts:

Im going to try messing with serial port hoping to figure that out. I am probably going to end up making a new control board for it that will support usb OR some more standard interface that can work in a programmatic way for my friends purposes.

This is a long term project so I will update it as I go.


Other stuff:

DataSheet on the chip on the led panels:
http://www.nxp.com/documents/data_sheet/74HC_HCT374_CNV.pdf

Well, the Zilog Z8S180 is an enhanced Z180, itself an enhanced Z80; the datasheet for that CPU is here. The 74HC240Ns at the top-right are octal buffers/line drivers. The 74HC374 is an octal D-type flip-flop. The chip labeled "LOADER" is more likely than not the firmware for the device on EEPROM. There's a nice obvious MAX232 there so you can tell where the serial is connected, I'm super-intrigued by the XILINX chip; I would guess a custom multiplexer, but that would seem like overkill for an FPGA to me.

I honestly have no idea the current game plan is to just spam the serial port with data until I get a reactoin document it and continue. if this fails i'm gonna actually try figure out how the board works. and if that becomes too much like work im going to figure out how each indivisual led panel works and just make my own hardware solution to controlling them. Tho hoping the first solution works

Have you tried seeing what the serial console shows yet? I bet it's something pretty straightforward. If worse comes to worse, PS/2 is not actually that hard to speak, so you could make a microcontroller inject the PS/2 key sequences needed to reprogram the device whenever you want to change what it says. Twitter notifier or Cemetech post notifier, perhaps?

The PS/2 interface is really laggy according to my friend so I dont think that would work very well. As for serial all I currently own is a usb to uart I dont own a serial cable I need to get one :/

(edit due to a uncannily good mood making me use the wrong faces)

I'm a little confused why you're laughing at your lack of a serial cable; that seems a bit mean? And you're grinning and squinting because you need to get one? I can't say that those emotions make much sense to me. Anyway, the FTDI (USB-serial) cable should work fine. Do you know the speed, parity, stop, and flow-control settings?

No I dont know any of the settings sadly :/

And the Serial adapter I have is a usb to 2pin uart. IDK how well that will work for this application :/

Well i ordered and received a usb to rs232 adapter. I have messed with it a bit but I have not been able to get any response out of it.

Any suggestions? I'm tempted to make a new control board for it just for the learning experience.

Can you dump the eeprom? It might have some clues...

Have you tried all the possible speeds?

I have tried a few but not enough to count. PCB_master I have no idea how to go about such a task. Any cheap suggestions?


EDIT: http://html.alldatasheet.com/html-pdf/55463/AMD/AM29F010-90JC/52/1/AM29F010-90JC.html


that is the data sheet for the eeprom

Ok so I have decided to scrap the built in controller in exchange for a M2233DEMO 68k/coldfire board

This board has a Ethernet library a large handful of I/O pins and a serial port. Which means it will be perfect for what my friend wants when I get around to coding for it.

The next thing on the todo list is to draw up the matrix board schematic in eagle cad so I can actually write software that interfaces with it lol

My friend has graciously donated me another free computer monitor. So this project is getting moved up my todo list so expect updates soon.

Great, I look forward to them. Are your goals with the project still the same: display arbitrary, programmable text on the display?

Yes that is correct. Preferably over a network socket But that's for a long while from now for starters its going to be over a usb serial connection via UART using the stellaris. The deadline for this project went from "when I get there" to the 13th. So I'll be stepping it up a bit ^^

OK So I took a look at this again. Took me a while but I finnally figure out how the led marquee functions in theory.

Each board has 3 input buses.

-clock
4 inputs
-data
7 inputs
-power
8 inputs

This means that with some proper logic i can control the hole board with a total of either

55 inputs

OR if i mix all the power lines across all the boards together.

31 pins

So whats the plan from here.
Either figure out which pin set to use (suggestions would be nice here please)
and get the proper components and assemble a protoboard

After looking at the previous control board you can see that they link the power and data busses across all the boards but have the clocks seperate.

So this makes it
4+4+4+4+8+7=31 inputs across the whole thing.

I am currently going to rig up my breadboard to control one panel. seems like a good plan. Will be showing if off on hcwp tonight and I will take some pictures to post in the thread

Woo progress

I decided to use the i2c port expander I have only because I didnt want to get lost with the gpio settings of the stellaris, and this way I can learn to use the chip I bought because I feel it will become invaluable to me in the future.

So while I wait for some stuff to download. Can someone explain how one actually makes a led matrix like this show letters? I know it relies on how humans perceive lights going on and off really fast but that is about it.


EDIT: I got my stellaris setup with Ti-Rtos. I'm liking how I Don't have to deal with task handling I just set a priority and code it in.

EDIT2: scratch the above documentation hell here we go
http://www.ti.com/lit/ug/spruex3l/spruex3l.pdf
^for safe keeping took me all day to find it for some reason...

So after about 4 months of not working on this i took at stab at it the other day with an arduino Leonard clone I had and I got it working

I have to rework the breadboard for it because its a rats nest as of the moment but I got leds to light up and that's a good start to me

So Another 8 months later and I started to play with this again.


Rawr.

It works Only supports 1 of the 4 panels So far. Reasons being no breadboard space and none of the components I need.

What is actually done on it? well it currently draws an image from a buffer in ram of my atmega32u4. Which works! Iambian generously put some time in last night to make me some buffer rotate routines so we get this



Todo? Going to get a schematic drawn up in KiCad print the pcb and make it work with the whole panel inside its case

Notes for that. 4 clock driver headers 1 of everything else.
Find proper transistors. Maybe use mosfets instead. Go relearn the difference between the two. Display is two dim with out a delay. Is that the transistors fault?