Noob:Building shield for large din/dout matrices

Hello all,

I have been an avid hacker of hardware for many years, and have recently decided to delve into more ambitious waters with a larger arduino rig, and I wanted to ask you kind people if the following is possible:

The project involves controlling a large scan matrix of LEDs, several hundreds, arranged in 16x16 matrices, and retrieving button data from an array of 16x16 buttons, too.

So I would need some very big shift registers to handle this. My question is more along the lines of what is feasible in terms of:

cost/size : will a finished pcb be as enormous as I fear? something like a 16x16x3 shiftOut PLUS a 16x16 shiftin would be large in footprint, even with smds, right? I plan to take the long road and work out a pro pcb layout in order to minimize size and assembly time.

learning : I am still going over the tutorials, but are there any resources specifically dedicated to running larger LED arrays like this, for instance LED signs?

functionality : Some demux hardware supports 4 “states” of LEDs, namely off, 2 pwm settings and then fully on - will these technologies translate to large arrays? From my readings there are two ways of handling scan matrices with ext. hardware demuxers: 1) maintain the storage of LED values on the computer, and 2) store the values on the LED drivers themselves - I would have to acheive 2) to make this project work.

Power : Hundreds of LEDs will suck juice - are there any tutorials on powering larger LED rigs in conjunction with the Arduino?

speed : will the arduino and serial interface be able to keep up with large amounts of digital data transfer for this? Clearing a LED matrix of 500 LEDs does require quite a bit of data output, I would guesstimate?

I really want to help design a board for connecting larger matrices effortlessly - currently I only see quite expensive boards for 8x8 LED control.
Thank you so much for helping out, I am really excited about getting into this project now.

Cheers,
Andreas.

sounds like your tackling a really big project.....

see how easily you can get smaller displays working, and try to experiment with some led light shows... get a feel for the environment. the job your talking about will require alot of patience, and time, so getting to be good at hooking stuff up would be helpful and beneficial in the long run of this project.

now for business... this project sounds like it can easily cost about 200 - 400 bucks, all depending on what you buy: rgb leds? super bright leds? dual color? regular? also the arduino: bluetooth? usb? serial? ( price only spikes with blue tooth model... ) and ofcours like you said ; custom pcbs that are large can cost a bit much, but not too much... and maybe you would like to use some sensors, to assist in the insurance of this finished projects longer life span...

please answer this so i can be more helpful:

how much expierence do you have with everything ? ( ex: arduino, led's, shift registers... )

sounds like your tackling a really big project.....

see how easily you can get smaller displays working, and try to experiment with some led light shows... get a feel for the environment. the job your talking about will require alot of patience, and time, so getting to be good at hooking stuff up would be helpful and beneficial in the long run of this project.

I totally agree. I hav virtually no experience with the arduino environment, but have worked with both midibox, prototyping boards and custom HID rigs in the past, so I do come prepared. Main area of research for me are the shift-registers and pcb layout.

now for business... this project sounds like it can easily cost about 200 - 400 bucks, all depending on what you buy: rgb leds? super bright leds? dual color? regular? also the arduino: bluetooth? usb? serial? ( price only spikes with blue tooth model... ) and ofcours like you said ; custom pcbs that are large can cost a bit much, but not too much...

I'm just going for a diecemila for this, since the project would need external power to drive the LEDs anyway.

well, depending on what is possible with regards to digital outs from the arduino, refresh speeds and so on, I would like, ideally, to hook up 16x16 rgb leds, such as these: http://cgi.ebay.com/50-pcs-5mm-RGB-LED-4000mcd-Common-Cathode-Free-R_W0QQitemZ140198666501QQihZ004QQcategoryZ66954QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (always loads of these available - not super-high quality, but since I would need 256 for the finished unit price is still an issue.) Another lingering concern of mine is the LED+button board itself... this would need to be quite an EagleCAD masterwork in order to be small enough (buttons over LEDs, four legs per LED, etc.) Fortunately I have a mate who's a bit of a pro at this stuff.

and maybe you would like to use some sensors, to assist in the insurance of this finished projects longer life span...

This isn't urgent to me at the moment, but an accelerometer is always welcome ;) My main concern would be the chips for the shift registers, which could amount to a lot of money, if they were like 10$/each. I do realize there is a lot of research ahead of me, but I am definitely looking at the long term of this, designing things properly before ordering big batches of things.

Thank you for any further advice, it's really appreciated, here at the onset of a large project.

Hi -

I've made a great deal of progress with a challenge similar to what you describe, with my current project: the Stribe. It uses an Arduino MINI to control a 1024-LED matrix, and accepts input from 8 analog sensors. These 8 inputs could be multiplexed up to 64 inputs with 4051 chips, or use the leftover digital pins (I only use 3 digital pins) for input. AND it all runs on USB power. The secret is the use of multiple MAX7221 chips - each one can power and control an 8x8 grid, and pulses the LEDs to conserve power (not visibly).

It's become a collaborative project with more people getting involved every day. There will definitely be info that will be of use to you, and hopefully you can contribute, too.

Learn more here: http://www.soundwidgets.com/stribe/

And there's a forum here: http://www.soundwidgets.com/smf/

It's all open source so take what you will - I hope it will save you some work.

Cheers,

phineus