If I wanted to drive RGB LED’s, I figure that I’d need 3 times the pins and therefore could exceed the 18 supplied by this board. Technically speaking if I could talk to more than 1 board at the same time, I could overcome this limitation but I’m not sure if the address is changeable from 0x54. Anyone got any further info?
Hmmm, I might be answering my own question in a sense here. The Adafruit 12-Channel 16-bit PWM LED Driver - SPI Interface - TLC59711 seems to be specifically for RGB and you can chain them and/or run LED’s in series as it’ll cope with up to 17v. That should cater for pretty much anyone’s needs, surely!
Sounds like you’re on the right track. Unfortunately the SN3218 is a fixed address device, you can certainly use a bus multiplexer to drive more than one, but it’s a bit of a faff when there’s a better solution out there.
I just tackled the same problem, one option to do this is to drive each SN3218 from its own software I2C bus (plus one from the hardware I2C pins), this way you could drive a handful of them (even if not the huge amount you could with TLC5940, TLC5947 and the like).
I’ve posted the code to do that at https://forum.arduino.cc/index.php?topic=358677.0
Why would one want to do that? Because SN3218 is quite a bit cheaper, both in breakout board format and as a standalone chip.