Ah, sorry I forgot to answer that. The TEC settings are percentages of full power. So if you set max to 80, the power will be limited to 80%.
Regarding the PB0, one loop = 1020ms. Within a loop the software:
1. calculates the cooling on and off times using a PID loop. Then
2. Sets PB0 = off
3. Waits the calculated off_time
4. Sets PB1 = on
5. Wats the on_time
repeat
For example, if the cooler is calculated to run at 50% the on_time and the off_time will be 1020ms/2 = 510ms.
Now, in theory we could reduce the time of 1020ms for one cycle to something smaller and this should increase the TEC switching frequency. In theory... but the resolution will suffer. For example reducing this 10x will only give us 10Hz and 100 step resolution. It may be possible to change delays to us... ask me once the main code is done
edit: just saw your messages that arrived while I was typing my message. Regarding power going down, can you try to reproduce what you did when you got a moment and see if it happens again.