I want to drive 672 RGB Leds with PWM, which mean I need 2016 PWM outputs.
I only want to use arduino to send the correct PWM signal to the leds, the main controlling ( effect creating/calculation ) will be done from pc which is connected to the arduino by usb/serial.
I was thinking of using couple Arduino Mega boards in combination with TLC5940 chips. The main thing are te costs 2016/16= 126 TLC5940, 20 EUR each.
I am hoping to get some better ideas to controll it and also cheaper ;P.
Err... all at once, one at a time, static groups together? My 300-or-so LED project is likely to use addressable switches so I can send out the ID of a specific switch to allow power to a specific LED. Actually dual-channel switches, so one switch can be instructed to power 2 LEDs individually. Also, I 'm not sure it can handle PWM.
Not sure what that looks like yet in my case, much less for your RGB requirements, but I hope that helps. They're about $1 per @ 1000.
Just to be clear: do you want to be able to set the color of each of the 672 LEDs individually? If not, you don't actually need that many separate PWM signals.
You might contact the people who make this gadget: it's probably simple for them to modify their servo firmware to do PWM for LEDs. And they would probably give you a bulk price if you're buying 125 of them.
My suggestion: for simplicity, attach 5 LEDs to each chip, and "waste" one PWM output. Then you can do 125 identical 5-LED modules.
First plan was indeed to control each led individually.
Since there isn't realy a cheaper solution I think I just to have to make groups like you are saying.
And CLaFarge:
Too bad it doesn't support hardware PWM, otherwise it would be a cheaper soluiton.
I have an idea, but you might not like it because it's not very cheap. Still, possibly cheaper than other options.
I design and sell RGB modules, like this:
You get a bright RGB LED with 10 bit PWM control of each color, and a simple shift register interface that an Arduino handles well. You would probably need to split this between several Arduinos, since the controller datasheet doesn't recommend more than 250 modules in series.
They start at $4.99 each but the discounts kick in rapidly. For such a large order we might be able to set up a special discount. Still, it's going to be over $2000.
It'll work though.
Right now we only have 610 in stock. By mid-July we'll have 750 more, and another 750 of the version without headers.
Patience, young Jedi: exhausted all possibilities we have not
Two important questions remain: how fine a control do you need over the color? 4-bit (4096 colors)? 8-bit (16 million colors)?
And how fast do you need to update the LEDs? Are you trying to do low-res video here? Or just put up pretty patterns that may only change every several seconds or minutes?
Keep in mind that you have to send out over 2000 individual level settings every time you update the entire display. That could be a metric (bleep)load of bits.
