Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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17.6.4.3. Transmit Path Functions

The MAC captures a timestamp when the start-of-frame data (SFD) is sent on the PHY interface. You can control the frames for which timestamps are captured on a per frame basis. In other words, each transmit frame can be marked to indicate whether a timestamp should be captured for that frame.

You can use the control bits in the transmit descriptor to indicate whether a timestamp should be capture for a frame. The MAC returns the timestamp to the software inside the corresponding transmit descriptor, thus connecting the timestamp automatically to the specific PTP frame. The 64-bit timestamp information is written to the TDES2 and TDES3 fields.