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C6678: No lights for ethernet loopback connector

Chris Johnson1
Expert 1715 points

Hello,

I am using Advantech's DSPC-8681e card and trying to get some network throughput measurements and run other network tests. I have taken the PA emac example and modified it to get it working with one chip on the card.

If I connect the card to a router with other PCs connected, I can send packets from the card to other PCs on the router and receive packets from the other PCs as well. Looking at the lights on the ethernet port when the cable is plugged in, I can see that the green light is on indicating a GbE connection.

If I try to instead connect a Superlooper GbE loopback plug to the card, no ethernet lights come on at all. Is there any additional or different setup needed for a loopback connector? Is there a recommended loopback connector to use or are there any possible problems with the one I am using?

The one I am using is here: http://www.cablesandkits.com/superlooper-gigabit-loopback-tool-p-1682.html?CAWELAID=120126460000010226&gclid=CJng5PHxg74CFa_m7Aod4TQArg

Chris

  • 0
    Genius 3420 points

    All-

    Adding some info, we read thru this post

    http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/t/119109.aspx

    which has reference to a Superlooper loopback plug connector.  The one we have is spec'ed for 1000base connections, and we've tried it successfully with other GbE RJ-45 connections (e,g, server motherboards) in our lab.

    -Jeff
    Signalogic

  • 0 in reply to Jeff Brower73
    TI__Mastermind 20790 points

    Chris,

    Did you get to work the light (LED)? Refer the below E2E threads,

    http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/p/119109/496912.aspx#496912

    http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/t/134415.aspx

  • 0 in reply to Pubesh
    Genius 3420 points

    Pubesh-

    No we did not get a successful LED indication of GbE loopback yet.  In reading through the posts you mention it seems clear how to get GbE loopback working with the EVM 6678.  Will a similar technique work with the DSPC 8681 PCIe card?  Is there an equivalent MDIO_enable_phy_loopback Gel script or source code excerpt for the BCM5461 PHY on the PCIe card?

    Thanks.

    -Jeff

  • 0 in reply to Jeff Brower73
    TI__Mastermind 42545 points

    Jeff,

    The card you've referenced is a product of Advantech. We don't have any more information than can be found on the Advantech website. In addition, you're asking about the Gbit Ethernet subsystem which is implemented with a Broadcom Gbit PHY. You really need to direct you questions to Broadcom. The Marvell PHYs that we've used do require some addition register settings to support looback but that is specific to Marvell and may not apply to Broadcom PHYs.

    Regards, Bill

  • 0 in reply to Bill Taboada
    Genius 3420 points

    Bill-

    Right.  Yes we think something similar has to be done with the Broadcom PHY to get the the Superlooper to cause the PCIe card to indicate a link is established.

    As it stands we can establish a GbE connection between the card and other network gear in our lab, so we're ok.

    Thanks.

    -Jeff

  • 0 in reply to Jeff Brower73
    TI__Mastermind 42545 points

    Jeff,

    It took us some time to track this down with Marvell. Unfortunately, Broadcom only provides data sheets under NDA and we don't have one with them. Advantech will have that information or you can contact Broadcom directly and try to set up an NDA with them. There are E2E posts that describe what is needed with for loopback with the Marvell PHY.

    Regards, Bill

  • 0 in reply to Bill Taboada
    Genius 3420 points

    Bill-

    Yes I agree a similar procedure is needed with the Broadcom PHY as with the Marvell PHY as mentioned on the other E2E posts.  We are familiar with the Marvell and Broadcom data sheet restrictions -- has been that way for many years.  I'll report back if we get far-end loopback working on the PCIe card.

    Thanks.

    -Jeff