Is there any a counter used to realize the timekeeping?

[ShaneCCC]

Maybe reference to below topic.

PTP synchronization and PPS output from Nvidia NX

Hi, We have two devices with NX. Each NX device controls its own camera via GPIO. We would like to synchronize NX devices via PTP. After synchronization, we would like each NX device to send a pulse per second to its own camera. Currently, we could synchronize two NX devices via PTP. Both system clocks are synced. But we are trying to find a way to send a pulse per second to the camera via GPIO. We tried a user-space program that will toggle a GPIO every second, but we see the pulses drift …