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[on:]

I have 12 of these Silent Radio signs. Each sign has two array boards that are connected by the processor board. I have a Mega 250 and was wondering could I connect them together using the 15 pin digital outputs and the on board clock to make the signs scroll a message. Also is there a way to link them all together and make one long sign using just the one processor.

[Reply #1 on:]

Need more info re: support chips on the module.

[Reply #2 on:]

on the array board with the led blocks there are;

 7) MICREL MIC5822BN,
24) ELM-2002EWB/P17 LED Blocks

On the control board these are the support chips;

U3 & U4 - R65C102P4 and R65C22P3
U5 -  MS62256L-10PC
U18 - TIBPAL 16L8-25CN
U19 - some sort of EEPROM
U6 - PC74HCT165P
U20 - CD74HCT161E
U21 - TIBPAL 16L8-25CN
U7 - CD74HCT93E
U22 - MM74HCT74N
U8 - 20 MHz crystal
U11 - MC74HCT244AN
U24 & U31 - SN74LS138N
U25 & U32 - ULN2803A
U11 - MC74HCT244AN
15) IRFZ34

The board has a power supply that feeds +24,+12,+5,+5rows,+15

[Reply #3 on:]

Closer Pictures of the support chips

[Reply #4 on:]

Ooh, that's gonna be tough. You've got programmable array logic (PALs), you've what looks like UVEPROM and SRAM.
If you don't have any interface documentation to go with the board, you've got a tough road ahead to figure these things out.

[Reply #5 on:]

There is no documentation on these model signs anymore. The company closed in '94. I do know that this was a DOS based program and this model had a remote type keyboard (which I have but it too is broken, it doesnt want to communicate anymore). I was hoping to remove the control board, just use the LED array, and replace it with the ARDUINO as the driver processor. Bob has one that works but his is a totally different set up with 7 drivers where this one is a 15. He used a UNO, 7) TIP120 to drive the LEDs and a 4017 decade counter to clock them in. Can the Mega with the aid of 15 TIP120's, no decade counter, be used. By connecting a output from the Mega digital to the collector, the #row to the emitter, and +5row power to the base drive enough to make a program scroll a simple message. Or does this have to be a PWM only.

[Reply #6 on:]

If the array has clear pins broken out for the rows & columns, then yes, a hardware solution to drive the anodes and sink the cathodes can be worked and multiplexing put in place to drive the array.

[Reply #7 on:]

The only visible pins showing is the rows. The second connector (starting at the top); (D or O)E, DIN, DOUT, CLK, STR, +5v. By connecting the clk line from the Arduino to the clk pin, +5v used from the Pwr Supply given, how would I supply the stream from the Arduino.

[Reply #8 on:]

Don't know.

(D or O)E, DIN, DOUT, CLK, STR, +5v

Almost sounds like SPI's CLK-MOSI-SS - but too many signals.

[Reply #9 on:]

On this board everything starts in a TIBPAL 16L8-25CN. When I looked up the data sheet It gives 9 pins are the input, but 18,19 and 12,13 are I/O. Then the signal goes to twin Darlington Pair chips that drive the IRFZ34 that direct link to the connectors of the led arrays. By sending a digital signal with the message in a stream on the I/O legs I could then interrupt the flow coming from the processor that comes with the sign and replace the signal from the Arduino. Then interrupt the clock and put in the clock from the Arduino.

[Reply #10 on:]

Sorry I had to stop because of classes, last semester was Intro to C++ and the next two semesters is Math for Game Programming with C++ Labs, so its been difficult.

 I was thinking about how to modify the sign to accept new hardware since the sign is so obsolete, There is a EEPROM that controlls the sign, a 27C256, I looked up the pinout of this chip and it has A0 - A14 and D0 - D7, it aslo has /0E, /CE, Vpp, Vcc and ground. On a Mega board you have the same outputs as well, So couldnt you pull the EEPROM, jump in wires corresponding to each one, basically turning the Arduino into the EEPROM? The EEPROM is where the program for the sign is held anyways, the memory chips is the buffer as far as I can tell. If this will work, I can add to the Arduino board a better way to communicate with it.

[Reply #11 on:]

PAL 16L8 is a programmable logic array part, you have no idea what these things are doing.
Most likely pulling code from the 27C256 and acting as a bit slice processor.
http://en.wikipedia.org/wiki/Bit_slicing

It'd be easier to strip everything off that was controlling the array drivers such as
twin Darlington Pair chips that drive the IRFZ34
and use the Mega to provide the control signals.

Or, pull the EPROM and the PALs, try to download their code out & reverse engineer it.
EPROM not so hard, just enable CE & WE and cycle thru all the address bits.
PALs, I don't know, never tired reading one back without a PAL programmer.

[Reply #12 on:]

So If I took a EEPROM reader/writer, I could look at the bit code. If I could do that though, I could reprogram the signs output, right?

[Reply #13 on:]

So If I took a EEPROM reader/writer, I could look at the bit code. If I could do that though, I could reprogram the signs output, right?

You propose to read the EPROM, assuming it contains 6502 code plus character set data and it is still good (looks like the tape fell of), disassemble than and try to figure this beast out?  If you are smart enough and have enough time you may be able to do it but I think the number of hours is going to be greater than desoldering reusable parts from this and rebuilding it yourself.

I'm not sure why I would care so greatly how something was witten way back when for a 6502 unless it was a classic video game or something like that.

[Reply #14 on:]

For me its like the Biggest Mountain. Its another thing to defeat. I could wire around it, and make up new electronics, but anything man made can be beaten, which is something I may consider, is to wire around it all.