Ethernet Design Example Components User Guide

ID 683044
Date 12/13/2021
Public

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1.4. Using the TOD Clock

Follow these guidelines when using the TOD clock:

  • 96-bit timestamp format—load the time-of-day using the time_of_day_96b_load_data[] bus or the SecondsH, SecondsL, and NanoSec registers. The bus value always takes precedence over the register values. When loading the time-of-day through the time_of_day_96b_load_data[] bus, the output is available in the time_of_day_96[] bus after one clock cycle. Hence, Intel® recommends that you add one clock cycle to the value of the time_of_day_96b_load_data[] bus to accommodate the latency.
  • 64-bit timestamp format—load the time-of-day using the time_of_day_64b_load_data[] bus. The output is available in the time_of_day_64[] bus after one clock cycle. Hence, Intel® recommends that you add one clock cycle to the value of the incoming time-of-day to accommodate the latency.
  • The TOD clock does not synchronize the 96-bit and 64-bit timestamp format.
  • The drift, jitter, and wander timers restart each time a new time-of-day is loaded, either through the signal or configuration registers.