SPRUIL1D May 2019 – December 2024 DRA829J , DRA829J-Q1 , DRA829V , DRA829V-Q1 , TDA4VM , TDA4VM-Q1
Precision Time Measurement (PTM) enables precise coordination of events across multiple components with independent local time clocks. Ordinarily, such precise coordination would be difficult given that individual time clocks have differing notions of the value and rate of change of time. To work around this limitation, PTM enables components to calculate the relationship between their local times and a shared PTM Master Time: an independent time domain associated with a PTM Root.
PTM defines the following components:
When using PTM between two components on a Link, the EP sends PTM requests to the RP on the same link. During each dialog, the RP populates the PTM Response message based on timestamps stored during previous PTM dialogs. Once each component has historical timestamps from the preceding dialog, the EP can combine its timestamps with those passed in the PTM Response message to calculate the PTM Master Time.
The PCIe core implements all of the features required to handle the PTM conversation between the requestor and responder in hardware. In addition, the Timestamp module (CPTS) is connected to the timestamp interface of the PCIe core so that events can be logged.