I need some advise on this -- driving 12 RGB leds individually. I was thinking of this model: LL-509RGBC2E-006. If I use these "plain" RGB LEDs with 4 pins, so that would mean I need to set 12 x 3 = 36 GPIO pins, which I guess means that I can't do this with a single Pi 3B (26 output pins available?). Also I'm weary of the total current (typical spec is 20 mA per colour, so 20 * 3 * 12 = 720 mA, and also it's written somewhere that you shouldn't put more than 16 mA per GPIO pin.
So... I guess I need some additional logic. Here are the questions:
- what kind of output board would I need to drive these with variable voltages? (I think voltage ranges are from 1.7V to 3.9V depending on the colour.)
- it is a problem if the cable between controller and LED is up to 20 metres? Should I use a particular cable (e.g. larger diametre, shielding, ...)?
- could I possibly use a cheap audio interface as DAC that doesn't remove DC offset?
- or would it be easier to use "addressable" LEDs? Only, I would need to cut the strip apart, as all 12 LEDs will have a distance of around 2.5 metres from each other.
If I can get it to work with two network'ed Pi 3B, that would also be ok for me. But if I lose too much current on the 20m cable, perhaps this is still too heavy for the Pi alone.
Edit: How about daisy chaining three Adafruit 16 channel PWM boards?