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DP83TD510E-EVM: Link drops when USB cable is connected

Wayne Hopkinson
Prodigy 180 points
Part Number: DP83TD510E-EVM
Other Parts Discussed in Thread: DP83TD510E

I have four DP83TD510E-EVM modules.  One of them drops the link with the computer via RJ45 jack when a USB is plugged into the USB port.  Let me name the individual cards as sets A, B, C, and D.  So A would be the combination of a single DP83TD510 and DP83822 and I'll refer to them as A-DP83TD510 and A-DP83822.  I can get sets A and B to function.  I can get sets A and C to function.  But for some reason set "D" will not maintain or establish link via the RJ45 port when the USB cable is plugged in.  The jumper settings are identical on A, B, C, and D.  If I get A and B up and running and (while running) I separate A-DP83TD510 from A-DP83822 and connect D-DP83822 it reestablishes a link and functions.  This tells me that there is an issue with D-DP83TD510.  In other words hot swapping A-DP83822 with D-DP83822 resulting in card set A-DP83TD510 mated to D-DP83822 works.  What could be causing this problem with D-DP83TD510?

  • 0
    Prodigy 180 points

    Would there be a way to reset the board to "from the factory" default values?

  • 0 in reply to Wayne Hopkinson
    TI__Expert 7040 points

    Hi Wayne,

    The toggling the switch S3 on the DP83TD510 EVM will return the PHY to the default values, you can also write register 0x001F=0x8000 to clear all register changes and reset the PHY to the default state. 

    Can I verify the problem you described initially? DP83TD510 board set D does not maintain link with the link partner connected to the DP83822 through the RJ45 connector. And when the DP83822 board is swapped with another DP83TD510 board the issue is resolved? Can you verify the DP83TD510 50MHz clock going to the DP83822? If you apply a reset to the DP83822 when link is lost, does the issue recover?

    Regards,
    Justin 

  • 0 in reply to Justin Lazaruk
    Prodigy 180 points

    Hi Justin,

    Your suggestion helped me find a workaround.  But to be clear, let me answer your question and clarify what happens.  When board set "D" is in use I am referring to the following set of criteria:

    • Board is powered up
    • Board is not programmed
    • Link IS established with partner via the DP83822

    The introduction of the USB cable brings the link down.  Pressing the reset button on the DP83822 brings the link back up.  Even with the USB connected during the reset process, programming the DP83TD510E with the USB-MDIO app brings the link down again.  With the board programmed, the reset button can be used one more time to re-establish the link.  This link is lasting and the board "set" works.  If I disconnect the USB cable, the board continues to work.  If I re-attach the USB cable, the link goes down and the board stops working.  Resetting the DP83822 doesn't help unless the main board is programmed again.

    -Wayne