love some advice on microprocessors

[BennyD]

Hey all, I'm a total newbie designing an art installation, and while I'm going to get someone to write the code for the display, and more than likely get someone way more qualified than myself to actually build it, I just wanted to get my head around the hardware involved a little, as I am hoping to get to a stage of doing it all myself somewhere down the line on other projects, but i want to sound like I half know what I'm talking about when I hire someone to build it for me anyway.

So my project going to involve, at this stage, 39 RGBA led modules, all individually controlled, each module (10w) having a separate red, green, blue and amber led. (http://www.ledengin.com/files/products/ ... 00MA00.pdf)

I'm thinking that I need 5 cables/lines per module (or is it 8?). And then I'd have to route them all back to a microprocessor that can handle 39 x 5/8 lines. I originally had 78 modules, and figured they could be controlled by dmx (512 channels), but thought I'd start with half that number of modules, as it seems like a complicated enough wiring job! Eventually I'm hoping to get a program written that could be copied onto an SD card or similar that would be inserted into the system so its no tconstantly hooked up to a laptop. I've got a background in electrical lighting, so have a basic idea of current/ wattage and dmx addressable sytems.

I'm obviously not expecting a complete breakdown, but I'd really appreciate a little knowledge about how many -/+ channels I'd need, and suggestions of a suitable microprocessor to handle them all. Or someone to tell me I've gone off track completely!

many thanks in advance,
Ben

[piratepaul]

Hi, firstly I am not an expert on DMX, Pauldf is a DMX expert.
I have read '' fundamentals of digital electronics'' by R Dueck. The book goes into all aspects of digital including programming machine code. I recommend a copy (ebay, I paid 99p) 1000 pages, it took 6 mts full time to read.

I think you only need 5/wires per module, earth is perminantly on so you only need to switch 4 switches per module.
Each LED drops a different voltage so resistors must be specifically chosen for LED colour.
The problem with a micro controller or TTLs is that the current drawn by any LED is high enough to fry the chip/s, so you will need to use a transistor for each LED..
But then there is DMX and there must be a switching box to replace the transistors hmmm.

I make that 39 x 4 = 156 wires + a common earth to each module.

Tar&stuff.

[piratepaul]

Microprocessors are collections of logic gates which can be configured by blowing fuses or electrically breaking circuits.
They are difficult to handle because of ESD and difficult to solder because of the pitch of the pins. You also need hardware and software to programme/configure them.
I would personally get a large number of TTLs ( any gate aca be made from NAND or NOR gates) on a large strip board and wire the pins to my own requirements. Its a bit more costly but you have a system that can be tested with a multi meter. TTLs don't suffer from ESD probs and are faster than CMOS ICs, they use more power.

There was an ad at the top of this forum earlier which was advertising Raspberry, it was using an SD card to store data so the card could be programmed then inserted in the slot. Beyond me to understand how that or SD cards work, interested to find out but...?

The TTLs would switch transistors which switch the 4 supplys to the modules.

Tar&stuff.

[BennyD]

Thanks piratepaul, really appreciate the info.. Yeah logic seems to tell me I need a ton of hardware between the software and the individual LEDs.. I'm going to do a bit more research this weekend, I'm sure I'll have even more questions to fire at this forum.. thanks mate.

[BennyD]

And I'd rather spend the cash to get it right the first time (or at least the second or third, heh....)

[piratepaul]

All you need is a transistor and a resistor for each LED. The microprocessor, or logic system could be done in a multitude of ways, it also depends what you call a microprocessor, some are very complex and some are CMOS so are problematic because of ESD. Some are not too micro and are just TTL ICs.
TTLs are easy any book on digital will tell you how to use them, I recommend "fundamentals of digital electronics" by R Dueck. Tells you every thing you need to know.
Pauldf will be about some time ...he is a DMX expert, DMX might be your solution.
Any way I can't really add to what I have said other than to design a TTLswitching thingi.

Maybe PM Paul for advice, he has only been about at weekends recently.

Tar&stuff.

[piratepaul]

I just noticed you said a ton of hardware between the software and the LEDs you need a transistor and a resistor for every LED ...and some sort of processor.
Raspberry is a possibility.

I am just going to shut up and stop causing confusion now.

Pauldf will be along at some point I spect, DMX and light shows are his middle name ...PaulDMXf...

Tar&stuff.

[BennyD]

Thanks mate, I'm going to search for that book now...

[Pauldf]

I don't know about soldering those LEDs, they are only 7mm square.
Are you trying to build some sort of matrix?

[BennyD]

Yeah you can get an MCPCB which would make soldering a little bit easier. Not 100% sure what you mean by a matrix, but each led would be independently controllable from the others, hence me thinking a DMX system would be the best way to conrtol colour mixing for each led, in essence 39 x 4 diodes, so 156 channels. It's more of an artistic project, so colour rendering is important, hence the RGB Amber fixtures, which give better colour representation than RGB's.

My plan is to get someone else to write the software coding to start with, and I'll probably get someone more professional at soldering to piece it all together. It's a large and more than likely expensive project!