LED controller

[charleskerr]

The two 485 inputs are unique to our SSD protocol, so that may seem unusually for some.

Just curious, I know NOTHING about pics/firmware/protocols..etc, just wondering for my little brain, with your protocol why are two inputs required? are you sending twice the info as normal? I am amazed how clean and simple the board looks.

Yes, we send two streams of data in our distribution network. We have images of this over at our site. We went with this approach to maintain our refresh rate of 25msec or less, and still have a reasonable about of channels. In our firmware, we allow one to switch back to DMX if they want, with the reduced channel count. Our dongle, when switched to DMX, actually will output two universes (since it has the second pair), so a tad easier to program/thread. Anyway, probably more then you wanted to know about SSD, but that is why we have two inputs.

 

[charleskerr]

As far as installing 0.1's I put them as close as possible to each chip so that track length, capacitance, inductance and resistance have a lesser effect on the supplies. I personally go through my pcbs and the last thing I do is fatten up the supply traces as much as possible and also put a via or 2 though between layers to reduce the length of traces.
It wasn't the pic-> tlc frequency stability that i was concerned about. It was the possibility of losing the dmx signal if there was too much drift.

Well, we don't normally use DMX, and for SSD, we actually use the built in UARTs. So far, we haven't lost anything using the internal oscillator, but will keep an eye on that. For DMX, the same is true, but we enable it only after we detect the MBB,SPACE,MAB. Again, we haven't seen an issue, but thanks for the item to keep an eye on.