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DP83640: 300ms offset between master PPS and local PPS

Brad Jackson
Prodigy 10 points
Part Number: DP83640

Tool/software:

Greetings,

I have been working on incorporating the DP83640 into a PIC32 project over the past few weeks.  I'm capturing all the relevant timestamps and the PIC outputs indicate that the PHY should be in sync with the master clock, but the PHY's GPIO PPS is consistently ~300ms behind the master's PPS signal. 

As an experiment I've tried to remove the delay manually by adjusting the clock but once I get into the microsecond realm the offset varies from run to run.  The strangest part is according to my timestamps I should be out of sync by no more than ~600ns.  

Has anyone else run into a similar problem?  I've tried multiple PTP algos but they all give the same result.  I'm happy to get into the weeds to give more info but just checking if this is a known or common issue that I've overlooked.  

Thanks!

  • 0
    TI__Mastermind 19621 points

    Hi Brad,

    Could you provide me with a block diagram of your setup which includes which clocks we are comparing and a scope shot showing the delay between the two clocks?

    Right now the understanding I have is that there are two boards, one being the Master clock board (MCB) and the other board is a Slave, syncing to the MCB. The MCB and Slave are connected via an ethernet cable. The Slaves PPS clock is being probed from the DP83640 GPIO pin, where is the master clock being probed? 

    Regards,

    Alvaro