Configuring PTP PPS Sampling Mode

Time-Stamping and Time Synchronization

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IntelĀ® PAC
Napatech SmartNIC
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User Guide

In this section

This section describes how to configure PTP PPS sampling mode.

PTP PPS sampling mode

When the PtpPpsSampling parameter is set to ENABLE, the SmartNIC works in PTP slave mode, synchronizing to a PTP grandmaster and sending PPS signals to the free-running SmartNIC clock to sample the time each second. In this case the PHY clock and the FPGA clock, which otherwise run from the same frequency source and work as one clock, are separated as shown in this figure. The clock in the FPGA is in free-running mode using the TCXO (temperature-compensated crystal oscillator), while the clock in the PHY is synchronized to the PTP grandmaster, and the FPGA can perform PPS sampling from the PTP time.

Separation of PHY clock and FPGA clock

Using the NtInfoTimeSyncSample structure in the information stream with NT_TIMESYNC_SAMPLING_PTP from the commontypes.h file as index it is possible to retrieve the sampled time stamps. When the SmartNIC is working in the PTP PPS sampling mode, PTP must not be included in the TimeSyncReferencePriority parameter. Furthermore SyncE cannot be used.

ntservice.ini code line

The syntax for the ntservice.ini code line configuring PTP PPS sampling mode is:

'PtpPpsSampling' '=' ( 'DISABLE' | 'ENABLE' )

Example:

PtpPpsSampling=ENABLE

Default value

This table shows the default value.

Parameter Default Value
PtpPpsSampling DISABLE