Accurate time capture and transfer between clock domains

摘要

A method includes requesting a time maintained in a first clock domain, receiving, in a second clock domain, a first time value from the first clock domain in response to requesting the time maintained in the first clock domain, determining, in the second clock domain, a latency associated at least with receiving the first time value from the first clock domain, and determining a second time value based on the first time value and the determined latency.

主权项

1. A method comprising:
sending, to a first clock domain of an integrated circuit (IC) from a second clock domain of the IC, a request signal in response to detecting, at the IC, an event corresponding to a packet being forwarded or transmitted or received, and requiring a time stamp, wherein the request signal indicates a request for a time maintained in the first clock domain; adjusting, in the first clock domain of the IC, a first time value from the first clock domain to compensate for a first latency caused by synchronizing the request signal to the first clock domain; receiving, in the second clock domain of the IC, the adjusted first time value from the first clock domain in response to the request signal; determining, in the second clock domain of the IC, a second latency corresponding to sending the request signal and receiving the first time value associated at least with receiving the first time value from the first clock domain; calculating a second time value using (i) the adjusted first time value and (ii) the determined second latency; and using, at the IC, the second time value to generate the time stamp for the packet.