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TM4C1294NCPDT: TM4C1294NCPDT Ethernet port test Ping failed

kevin.huang_FJXM
Expert 2925 points
Part Number: TM4C1294NCPDT
Other Parts Discussed in Thread: EK-TM4C1294XL

hi Teams:

When using the Ethernet port of your IC: tm4c1294ncpdt-t3, it is found that 1. The 100m communication rate is not on the Ping of 100m network cable, and the communication can be achieved by using 10m network cable of the same length (100m). 2. During signal test, the rising edge and falling edge are too large (eye diagram test can pass).

Please help analyze:

1. The reason why 100m network cable communication is not available for 100m.

2. The rising and falling edges of the signal are too large. thank you!

remarks:

The attached figure is the wiring and schematic diagram (both impedance 100 and differential are processed.)

  • 0
    TI__Guru**** 184426 points

    Hi Kevin,

      Sorry, I don't have much knowledge on Ethernet at physical or electrical level. I have a few comments. 

      - Looking at your schematic, I don't see a protection diode on the differential signals. I see you connect to RJ45 with an integrated transformer.  Protection diodes is quite important or risk damaging the chip. Please refer to the TM4C129 system design guideline for details. https://www.ti.com/lit/pdf/spma056

    - It will be easier to troubleshoot if you could do the same measurements on a EK-TM4C1294XL LaunchPad. What do you get? Please show your ping result on both the LaunchPad and your custom board. 

    - Run Ethernet examples from TivaWare on both the LaunchPad and your custom board and then do your benchmarking again. 

  • 0
    Prodigy 10 points

    • Hi  Charles Tsai

      Thank you very much for your advice        We currently have no demo for design comparison    As for this IC, could you please help confirm whether the 100M network cable can run at 100m    If so, what registers or other configurations do we need to configure   so that we can check our code to see whether the configuration is in place  
  • 0 in reply to rongyue guo
    TI__Guru**** 184426 points

    Hi,

      Do you mind explaining what "100M" and "100m" are? Do you mean "100M" as in 100Mbps and "100m" as in 100 meters? As far as the MCU, the Ethernet controller/PHY supports 10/100Mbps data transmission rate. If you run any of the Ethernet examples, it is configured as follows. I will suggest you run these examples first. 

    #define EMAC_PHY_CONFIG (EMAC_PHY_TYPE_INTERNAL | EMAC_PHY_INT_MDIX_EN | \
    EMAC_PHY_AN_100B_T_FULL_DUPLEX)

  • 0
    Guru 55683 points

    Hi Kevin AKA Rongyue,

    Charles has the right idea to check the design guide, he posted snip of ETH0 schematic for reference.

    kevin.huang_FJXM said:
    2. The rising and falling edges of the signal are too large.

    Perhaps remove C88, C89, C90, C91 to reduce TX/RX signal magnitude and roll-off. For R59 (CT) 100n would be more feasible placement in my opinion.

    Regards,

  • 0 in reply to Genatco
    Expert 2925 points

    hi Gi:

    These methods have been tested before. Similarly, a 100M network cable can communicate at 10Mbps, but not at 100Mbps. Please take a look.

  • 0 in reply to kevin.huang_FJXM
    Guru 55683 points
    kevin.huang_FJXM said:
    but not at 100Mbps. Please take a look

    Yet where do you see 100nF caps on TX/RX differential pairs in TM4C129x design guide? Perhaps your schematic show 100pF (c88-c91) filter caps but even that seems odd too.