Hey milowe, I know you've probably long since moved on and are probably occupied with the Ambex these days but I was wondering how far you got with controlling the Hottop. I finally got around to interfacing with the control board on my "B" this weekend and I had a couple of quick questions for you or anyone else who's played with this thing before... first, any luck finding any info or figuring out how to use the INT pin on the newer boards? Also, what PWM period are you using to drive the heater and fans? I'm not sure what the optimal periods are but I'm currently using two seconds and 100ms, respectively. Anything too much over 100ms for the fan and it starts to get choppy... but even at 100ms, there's still a very, very slight choppiness that's not present when driven from the stock controller so I know there's probably a more optimal period (maybe related to the fan rpm or something?). The heater seems to be pretty even/controllable at two seconds. Are you doing PWM through code or does the Arduino board have that built-in (I think I remember reading something about that in the specs on one of the boards)?