I am trying to accurately measure the time between two rising edge events on a pin, using an interrupt, so that every rising edge of a pulse train triggers the ISR. Inside the ISR I need to be able to read from a timer to capture the time since the last rising edge. I am familiar with using a timer to trigger an ISR, but can't wrap my head around how to capture a precise microsecond time from somewhere from within an ISR. Is it possible to read a GPT or QUAD timer directly to create a timestamp, for example? Thanks.