I need to control up to 50 LEDs from a computer, and possibly tri-color LEDs, meaning about 150 different pins to control. I really have no clue where to start, so thought I might post here to see if anyone has any ideas.
Using an Arduino as an intermediary between the LEDs and computer would be fine.
I'm programming savvy, and hope to eventually use Python as the controller language.
even if it's self promotion, macegr is right, if you don't need to have all your leds in a tight matrix but you're ok for some space between each (with a diffuser on top, for exemple), blinkM are a good solution.
The BlinkM will let you run a lot of lights on a single bus. You just have to program each one with an address, then talk to them individually.
The ShiftBrite above will do the same thing, except they are daisy chained so no address programming, and don't have programmable scripting on board so are a bit cheaper for a straightforward LED control app.
Very cool. I know this isn't exactly the purpose of a BlinkM, but is there a way to mod one so it can drive a relay? I'm guessing the LEDs are getting something in the range of 3.3 volts? Not the ideal voltage for a relay I know...
You would not want to run a relay on PWM. The answer is yes, you could mod a BlinkM to be an I2C-controlled relay. However, you'd need to add a driver transistor, and it's not the easiest or cheapest way to do it.
If you want to control a bunch of relays from an Arduino, the best approach is to use a simple shift register and darlington array which can be daisy chained and control 8 relays per unit. Here is a quick single-sided, through-hole design I made a while ago: