FoxFireX

Do all of your circuits share a common GND? They Should.

Yeah, all grounds tied together. My guess has been that there is some sort of voltage shift happening somewhere along the line that's either corrupting the serial line between the chips, or is causing its reference voltage to determine high/low on that line is getting shifted. Seems possible with the different LEDs going on and off, but at the same time I'd expect the TLCs to already be able to handle that.

I've been working on a project where I need to do independent control of quite a few (~150) LED channels. Many of them are RGB, some not. Anyway. I've been working on it using TLC5941s to this point, and thought things were going well, but I'm starting to hit some roadblocks. While on the breadboard, I was able to daisy chain two chips with no problem, but knowing the Netduino has a maximum current through its 3.3V out pin, I planned the standalone PCBs to have independent power supplies. I have one board that has a single TLC chip and the timing logic, and three boards with three additional chips, each with an independent power supply connection. The first chip works as expected, but the daisy chain boards start showing unexpected behavior; much of the time, the shift register values flow to each chip and output as expected, but far too often the resulting LED states are incorrect, sometimes extras on, sometimes off. My best guess at this point, from some of the reading I've done, is that I may need to add decoupling capacitors, but my first attempt hasn't solved the problem. So, in search of answers, I was looking around and found this thread. The main question I find myself looking at now is this: Am I better off trying to continue troubleshooting with the TLC5941s, and eventually probably ordering new PCBs and new chips, or would I be better served to switch to another solution like the Adafruit boards mentioned here? If I switch, will it be compatible with the LEDs I already have set up? (Don't remember if they were common anode or common cathode, just that it was TLC5941 compatible.) If I go for this, I'll have to order a set of ten boards, which it looks like would be supported, but I'd really hate to sink $150 into this solution only to fail again. Anyone with experience on either/both approaches who could provide some insight?