I have a signal that is going to the analog comparator. The CPU (M328p) is running on the internal 8MHz clock at 8MHz. The signal has a brief spike of 0.2 to 0.4uS followed by a 7-8uS plateau. I need to measure the plateau, but ignore the initial spike. The uC creates the pulse, and there is a little propagation delay after that. So, I know when the pulse is coming. Is there some way to turn on the AC 1-4uS after the spike is generated, so it will sample only the plateau? Adding low pass filtering to the external hardware may be hard to do with excessive impact on the measured signal.