Driving 20 Common Anode RGB LEDs - Having Trouble Getting Started

Thread Starter

PropForge

Joined Mar 5, 2016
14
I have a project in the works that I would like to add lighting to; as of now, I want to end-light 10 horseshoe-shaped ribs from either end, so 20 RGB LEDs total. The problem I'm having is that I just don't know where to begin.

My requirements are as such:

20 RGB LEDs (common anode, spec'd at 20mA each R:2-2.2V and GB:3-3.2V)
All LEDs are same color mix during animation
Driven via battery (9v, AAs, etc)
Arduino interface

My preferences and nice-to-haves:

Adjust LED brightness via software (animation becomes brighter every cycle)
Adjust color-mixing via switch/pot
Individually controlled (rather than paired-only)
Avoid individual resistors for each LED leg (constant current)
Uses a Pro Micro as I have extras begging to be used

Off the bat, I was thinking I could kluge something together using MAX7219s I have on hand, but as those are meant for 8x8 common cathode, I thought to look for something a bit simpler.

I then considered 74HC595s, but I'd have to add discreet components I'd rather avoid, unless I'm missing something.

Going with the idea of shift registers, I found the TLC5940, but even it seems to have some idiosyncrasies, so I'm not sure if it's worth it.

My thinking is, if I am using the same color on all the LEDs at the same time, I could use 3 PWM signals off the Arduino to all the LEDs, and switch them on and off through their common anode. I just have no clue what direction to go in. RGB LEDs in an arrangement is new ground for me, so I plead a fair amount of ignorance. Every example I come across just seems wildly different, I can't seem to find common traits to work from.
 

Thread Starter

PropForge

Joined Mar 5, 2016
14
I think you need to flesh out your project a little more, and ask specific questions.
Using an Arduino Pro Micro, and without delving into the realm of WS2812-connected LEDs, what would be an efficient way be to drive 20 common anode RGB LEDs at 20mA with the following conditions:

1) Brightness control via software
2) Color control via software on-the-fly
3) All 20 LEDs are the same color at any one time
4) Battery-powered
5) Minimal passive components
 

Thread Starter

PropForge

Joined Mar 5, 2016
14
I've opted to use addressable LEDs instead of trying to kluge something together, so this thread can be locked/deleted.
 
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