Large Matrix

Me and a friend would like to build a large (a little bigger than human) led matrix. The number of pixels is less important than the total size. We are not sure if we want rgb or white leds. We consider to work with the arduino mega adk because of additional android experiments. We are totally new to doing arduino projekts, so it would be best to follow a route that has proven itself. We are waiting for a probable funding of the projekt of say about 500 euro's

Does anybody know a way to connect and control a few hundred lights? We can do some soldering, but are far from electronic geniusses. Also for the programming we hope to use open source. Of course we want to invest time to study a bit, we have one or two days a week for three months to do this.

What to do? Where to start?

One simple method is to use addressable LED strip (or LED pixels) with IC WS2801 or LPD8806 for example. You can control each individual pixel and there are simple libraries for Arduino.

The number of pixels is less important than the total size.

This is the more important parameter actually, than size. One pixel or 10.000 is a huge difference from hardware point of view, the same time one pixel could be as big as a house.

Here are some open source projects that use a large number of LEDs and can be modified to your specs: Peggy 2 (25x25 single color LEDs) http://evilmadscience.com/productsmenu/tinykitlist/75-peggy2 ClockTHREE (16x10 RGB LEDs) http://timewitharduino.blogspot.ca/2011/09/clockthree-v2.html

Magician:

The number of pixels is less important than the total size.

This is the more important parameter actually, than size. One pixel or 10.000 is a huge difference from hardware point of view, the same time one pixel could be as big as a house.

I said this because I would go for the most logical solution in terms of linking hard and software. Something like 25 * 25 would be great.

florinc: Here are some open source projects that use a large number of LEDs and can be modified to your specs: Peggy 2 (25x25 single color LEDs) http://evilmadscience.com/productsmenu/tinykitlist/75-peggy2 ClockTHREE (16x10 RGB LEDs) http://timewitharduino.blogspot.ca/2011/09/clockthree-v2.html

I read about the Peggy 2 and had the same thought. What I cannot find, is how to translate it to a bigger format.

is how to translate it to a bigger format.

If you mean more LEDs, then you need to add one or more shift registers (plus the transistors). If you mean making the display larger but with the same number of LEDs, just use a bigger (wood) panel, and connect the LEDs to the PCB with wires.

I’ve got a board with 12 shift registers, you can directly control 96 LEDs with it.
They are high voltage, high current shift registers, the TPIC6B595.
Outputs only sink current, so you would wire up your 96 LEDs with current limit resistors and connect the LEDs cathodes to the board and the power supply ground to the boards ground.
Offboard USB/Serial adapter needed for downloading sketches, or (pop the '328P chip, program, and reinstall).
Available for $6.50 for a bare board & schematic/parts list, or I can assemble one for you for more.

TPIC6D595.pdf (465 KB)

CrossRoads: I've got a board with 12 shift registers, you can directly control 96 LEDs with it. They are high voltage, high current shift registers, the TPIC6B595. Outputs only sink current, so you would wire up your 96 LEDs with current limit resistors and connect the LEDs cathodes to the board and the power supply ground to the boards ground. Offboard USB/Serial adapter needed for downloading sketches, or (pop the '328P chip, program, and reinstall). Available for $6.50 for a bare board & schematic/parts list, or I can assemble one for you for more.

Thank you for your offer. I keep this option in mind. I hope I understand your english right, but what you are saying is your board cannot communicate directly with a computer? Because that is what interests us the most: Experimenting with the lights when its ready!

but what you are saying is your board cannot communicate directly with a computer?

No he is not.

board cannot communicate directly with a computer

As long as the board has an FTDI connector (which it has, in the lower left corner of the photo), it can communicate with the computer. Actually, this is the way to upload the sketches to the board.

That's correct, a USB/Serial adapter such as FTDI Basic would plug on, either directly or via extension cable, to make the USB connection to a PC. The Header pins can be straight pins, or right angle pins, whatever your application calls for.

Unfortunately the funding that was more or less promised to us for this project did not turn out so well. We still would like to do something like this, but I think we must study a bit before asking more questions. Especially the technique between an arduino mega adk and a lot of bright leds is what interests me now.

I did not have a look at the playground section before asking my question, so will do that first now.

Thank you for your replies.