Ah ha, there's the missing info.

With the lines ...
Code:
va = (v*(100-sag[0]))/100
I'm measuring each one at about 125us. There's 3 of them, so that's 375us, plus the 70us I measured for the main loop last time, for a total of around 450us.

Timer1 is overflowing every ~230us, so it's definately missing the Flag's.
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