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[FAQ] LP-AM261: Unable to get MAC Port link up with AM261x-LP + Automotive PHY add-on-board (DP83TG720/721)

Shaunak Deshpande
Genius 15182 points
Part Number: LP-AM261
Other Parts Discussed in Thread: SYSCONFIG

Tool/software:

Hi experts,

I am using the AM261x-LP. I am using the automotive-add-on board (DP83TG720/721) on top of the LaunchPad. I have followed all the steps mentioned in the documentation, checked syscfg pinmux, but I am unable to achieve a MAC port link up and establish a proper communication with the AM261x-LP.

Can you please help debug and provide the steps to achieve a successful link up, have MAC Port open and establish a successful ethernet communication?

  • 0
    TI__Genius 15182 points

    Hi,

    Please follow the below points:

    1. Ensure proper hardware connections:

    Ensure that the add-on-board has been screwed on properly using the screws and spacers. If it is loose, there will be connectivity issues, if too tight, the on-board connector might get damaged. Refer the user guide: https://www.ti.com/lit/ug/spruja9a/spruja9a.pdf for the add-on-board.

     2. Ensure Syscfg settings are correct:

    In syscfg, make sure the board is selected properly for Industrial PHY or Automotive PHY. Make sure the correct MAC port is enabled. This can be check under the Enet (CPSW) section of Sysconfig.

    In case of E1 launchpad, the MAC Port-1 is connected to Ethernet-conector-1 (on-board labelled), MAC Port-2 is connected to Ethernet-connector-0. In case of E2 launchpad, the MAC Port-1 is connected to Ethernet-connector-0 and MAC Port-2 is connected to Ethernet-connector-1.

    Remember this mapping when enabling MAC Ports through syscfg and Make sure that the MAC Port is tied to the correct Ethphy (CPSW) setting. Also, make sure the PHY address mentioned in the Ethphy (CPSW) is correct. This is necessary to have a proper PHY connection and getting the PHY Alive.

    3. Ensure that the Link partner is capable:

    Ensure that the Link partner is capable to run the interface you have selected. For example, For 10M, the link partner must only have 10M auto-negotiation advertisement enabled, If this is not the case, either PHY straps need to be modified, or driver needs to be adjusted. If the link partner is not able to communicate with the PHY connected to AM261x-LP, you might not see MAC Port Open and the ethernet packets might not reach the device.

    If needed, get a DUMP of PHY registers using GEL scripts and compare with the expected values as mentioned in the register guide and PHY Datasheet. Refer the steps mentioned here for getting GEL scripts output: https://dev.ti.com/tirex/explore/content/am26x_academy_10_00_00_00/_build_am26x_academy_10_00_00_00/source/debug_guides/ethernet_debug_guide.html#gel-scripts

    4. Ensure that the Master/Slave mode is configured correctly.

    If both the ends of the MDI bus are in master or in slave mode, you will have issues to get a Link-UP. This results in bus contention, initialization issues, PHY management conflicts and Link establishment. Make sure there is at-least one master. To force your AM261x+DP83TG720-EVM into master mode, in Ethphy (CPSW), add the below lines

    .MasterSlaveMode = DP83TG720_MASTER_MODE

    Similarly, for forcing into slave mode, assign the value as DP83TG720_SLAVE_MODE. Re-build your application after making any change in the syscfg file.

    5.Ensure that the PHY/on-board PHY connector has not been damaged

    In some cases, your PHY board or the on-board PHY connector can get damaged. As a result, you might see unexpected packet drops and CRC errors.  Try running the ENET_CPSW_LOOPBACK (https://software-dl.ti.com/mcu-plus-sdk/esd/AM261X/latest/exports/docs/api_guide_am261x/EXAMPLES_ENET_CPSW_LOOPBACK.html) example and check if you see unexpected drops or CRC errors.

    Regards,
    Shaunak

    Checkout more AM261x FAQs