Figure 2
From: Motmot, an open-source toolkit for realtime video acquisition and analysis
Overview of CamTrig USB operation for synchronizing multiple clocks. As described in the text, the CamTrig USB device allows the host computer to accurately estimate the timing of external events. The clock onboard the CamTrig USB device is a crystal oscillator driving a counter/timer to emit trigger pulses at very regular intervals. USB requests allow the host computer to build an accurate model of the time of events on the CamTrig device in its own time frame of reference.