PHC Synchronization with Onboard GNSS

Grand Master System Diagram

Supported cards are listed here: https://docs.nvidia.com/networking/display/ConnectX6DxEN/Introduction

If the boards are GNSS-enabled, connect the ConnectX PPS input to the GNSS module's PPS output.

1. Use the following script to identify the serial console for the GNSS receiver.

   Copy

   Copied!

               
   
               
   #!/bin/bash
    
   for d in $(find /sys/bus/usb/devices/usb*/ -name dev); do
       (
           sysp="${d%/dev}"
           devname="$(udevadm info -q name -p $sysp | grep -vE '^bus')"
           [[ -z "$devname" ]] && continue
           eval "$(udevadm info -q property --export -p $sysp)"
           [[ -z "$(echo $ID_SERIAL | grep 'u-blox')" ]] && continue
           echo "$DEVNAME is a serial console for $ID_SERIAL"
       )
   done
           

   Example output:

   Copy

   Copied!

               
   
               
   /dev/ttyACM0 is a serial console for u-blox_AG_-_www.u-blox.com_u-blox_GNSS_receiver
           

2. Find out the PHC device in Linux:

   Copy

   Copied!

               
   
               
   <find which /dev/ptpX>
           

3. Synchronize the PHC on the card to the GNSS receiver:

   Copy

   Copied!

               
   
               
   ts2phc -c /dev/ptpX -s nmea --ts2phc.nmea_serialport /dev/ttyACM0 --ts2phc.pin_index 0 -l 7 -m