LED display control / syncing

I am not sure if this is the correct forum, if it is not, I apologize.

Hi, my name is Ethan and I am a high school student currently working on a project.
The idea behind the project is to build a hologram machine using a Led Display(s) and a lens. The lens moves at a rapid speed and the Led system needs to be synced to the speed of the lens. Thus, I was hoping to buy the materials to do this; however, I was not sure of what to get as I am not familiar with these kinds of electronics.
I was looking at:

Duel Color LED Matrix (Medium size / 2x2)

with a

Arduino USB board (To connect to the computer and control the LED matrix)

And some kind of optical censor to sync the lens position and the LED display

So here are my questions:

  1. Will a Arduino USB board allow me to control a specific LEDs on the LED matrix?

I have been told that the Arduino USB board does not have enough I/O pins to control each LED, but it will be able to control some. If you can give me some more insight into what kind of control I will have over the LED display that would be great.

  1. Can a Arduino USB board be used to control more than 1 LED matrix (for instance 4)? If so, will I lose come control over each individual LED?

I have been told that to use more that one board it is better to use a serial enabled LED matrix. If you can shed more light on this subject that would great. I was also wondering if I use a serial enabled LED matrix, is a Arduino board is still useful for controlling the LED displays?

  1. Is a Arduino USB board the best device to program a LED matrix with if I want to be able to control each individual LED? If not, what would you recommend?

  2. What kind of optical device can I use to sync my lens and LED display?

  3. Is it possible to incorporate the syncing of the lens and the LEDs into my program?

If you can answer any of these questions that would be really great. I am hoping to finish
this project before the end of January, but I really need to know if the items I am looking at will work with what I am trying to do.

Thank you for your time.

First off I'm not really sure how "holographic" this is going to be.

Is a 2x2 matrix just 4 LEDs? That is 8+ pins for dual color? This sort of depends on the device you choose.

I think you need a stepper motor (probably bipolar) to control a mirror, not an "optical sensor." Alternatively you can use a motor that steps back and forth at a known frequency (or write a program to do this).

The key to this is probably going to be persistance of vision (POV), that is that you don't need to leave the LEDs "on" all the time, but rather turned on/off quicky to give the impression that multiple LEDs are on. To do this with an LED matrix you'll need a Johnson counter (CD4017 can be used for this). The counter "enables" one of the rows of the matrix and then you output what LEDs you want on. So you need somethign like 6 data lines for a 5x7 matrix (not bad for 35 leds). 1 counter trigger and 5 LED controls. I have some code for it lying around that I can post if you're interested.

You can control multiple arduinos with SPI or some other kind of inter-IC protocol or even just simple 1/0 on the digital lines to trigger an action on another arduino (say....move motor x degrees).

Read up on optics and POV (look at barcode scanners), and draw up some kind of design.

Ethan,

This is the right place for your post.
By "Duel Color LED Matrix (Medium size / 2x2)" I'm guessing you mean 2x2 inches and it's a 2 color 8x8 matrix with 64 leds - is that correct?

If so, I'd suggest looking at "LED Lights and Displays" in the Playground for starters.

http://www.arduino.cc/playground/Main/InterfacingWithHardware#Output

You will find that there are several ways to drive them - either with extra chips or directly (there are enough pins).

Also Google "Arduino LED matrix" and you can see what people have done so you get an idea of the capabilities.

As far as "syncing the lens" by reading some kind of position sensor - this is not unreasonable either.

After you do a little research you will be able to ask more specific questions that will be easier to answer.

Hope this helps.

BroHogan you are correct, I am going to be using a 2x2 inch square LED matrix that contains 64 LEDs. For the driver I was looking at a Maxium 7219. I was not planning on direct wiring the LED display to the Arduino board.

As for the optical sensor, I really do not understand how to connect one to my system. Would I be better off trying to connect it (the sensor) to my computer and incorporate it into the program, or is there some way to connect it directly to the arduino board. If the optical sensor can be connected to the arduino board would the board supply power to the sensor?

I have read up on some other people doing similar things, and I think I have a fairly clear understanding of what to do beyond the sensor.

As for the holographic part of it, that comes from the lens which is completely separate from the electronic part. Unfortunately, it is so separate from the rest of the equipment that I must find some way to sync the lens and the LED matrix.

Thank you for your responses, any other ideas/help would be greatly appreciated.

I've been working on a project that requires controlling 32 LEDs, (A binary clock/calendar). So I checked out the shift out tutorial on arduino.cc

I could not easily locate a 74HC595, but a bit of reserch shows that Jaycar has the Texas Instuments 74HC164 http://www.jaycar.com.au/products_uploaded/ZC4857.pdf avaiable instead.
A bit of poking round and checking the Datasheet, and messing with the shiftout tutorial, I've finally got it working

These chips do not appear to need a latch signal, I've used the shiftout tutorial code, with the latching deleted. It appears that by having the Clear pin permanently on HIGH, the clock signal is all that is required.

Attach the Clock signal to Pin 8, Data signal to pin 2, attach Pin 9 (VCC) and 14 (CLR) to +5V, do not connect the latch, and the single chip Shiftout code will function. (you can delete the Latchpin lines in the code)

Other chips in series are connected the same way, except for the data line, which is daisy chained from pin 13 to pin 2 (Yes, both the LED and the Serial in Pin are connected to Pin 13), and again the shiftout two chip code will work (again you can delete the latching lines). I've currently got 4 of these chips working in Series, giving me my 32 LEDs to play with.

You can perhaps set up one serial array for each channel, and drive 30+ 3 channel LEDs from only 6 pins on the Arduino.

Hey.

Jaycar does have the '595...

http://jaycar.com.au/productView.asp?ID=ZC4895