6 ch PWM acting goofy - Fixed but not solved.

Hey all, I am working on a pine wood derby car and am adding a gagillion leds to it. (this is the adult league, not my sons, so relax) Many of the leds are fine to just be straight on and straight off, but the mid section where the uHC (micro Hadron Colider) is housed sits an array of 12 leds on each side. These will be connected as 4 sets of 6 LEDs each (1 pwm channel per LED, per set). Each tied to the 6 PWM lines. Now in my proto set up, (just a set of 12 leds), I am am getting great results with all sorts of patterns and such. Whats really cool (and fun) is that this is all being controlled remotely via an xBee controller I made so that when the race starts I can have it go crazy vs. sort of a calm throb when it is just sitting there.

The problem... when I am fading out the PWM it does not seem as smooth as the fade in. The fade in is nice and smooth. But fading out it fades for a bit, but then just drops out. Whats worse is that they do not drop out all at the same time. Some last a wee bit longer than the others then die too. The place that it drops out, I would call about 75% brightness on the fade in side. So it is not even like it is just really low. When I am doing some fast ripple patterns, one could not tell, but when I am doing a full set up then down it is really abrupt. So is there a fluke with the some of the pwm channels perhaps not being as strong as others? Any ideas as to why this might be happening?

Never mind. I am not sure why, but I was working on it last night and it was working fine. I have no idea why it was not working one night then working the next. But for now. never mind. Thanks.

Are the LED's connected directly to the PWM pins, or are you using things like FET's to drive them? I have noticed that sometimes the pins tend to float, which can cause things to stay on for a bit longer than usual.

With lots of LEDs it sounds like you might need some extra decoupling:- http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html