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DP83630: DP83630 - synchronization when daisy chaining

Part Number: DP83630

Hi all,

We have a product where the product owner decided to include two Ethernet PHYs (DP83630 that supports IEEE-1588 PTPv2) for future use such as synchronizing multiple boards and data transfers. The board does not contain an MCU, instead we have a FPGA, and the design provides limited ethernet switch functionality so the PHYs can be used for daisy-chaining. Right now we have not implemented the necessary code for controlling the PHYs and interfacing the FPGA on the board.

I know that we are vague when it comes to AL-1032 and the functionality of the ethernet ports. The project lead for AL-1032 added two ethernet ports so it could be used for synchronizing the devices, so the PHY selected supports IEEE 1588 PTPv2. Another possible use case that he had in mind was that it could be used for acquisition / generation using UDP. We have limited ethernet switch functionality so they can be used for daisy-chaining.

What performance can one expect when daisy-chaining multiple boards? How many can one daisy-chain while maintaining good synchronization?

If the PHYs are synchronized the idea was to generate clocks signals through the GPIO lines for circuitry on the board (ADCs and DACSs through the FPGA), with the goal to achieve synchronized acquisition / generation on all boards.

The frequency of these clock signals would be accurate to the 1588 time of the board and since all boards are synchronized in time, we should achieve synchronization when acquiring / generating signals. Start of generation / acquisition could be achieved through future timed event or an external physical signal sent to all the boards.

Your feedback would be greatly appreciated!

William

  • Hello William,

    Please excuse my ignorance but I am not getting the correct picture of your application here. Kindly help with following : 

    1. A basic block diagram of the board highlighting connections and required data flow highlighting the daisy-chaining topology being discussed here.

    2. When you say "what performance can one expect when daisy-chaining multiple boards?" , which parameter are you  looking for to quantify the performance?

    3. When you say "How many can one daisy-chain while maintaining good synchronization?", what is the pass/fail criteria of syncronization here?

    --

    Regards,

    Vikram