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DP83TG720S-Q1: DP83TG720S-Q1 related issues

jeno.zhang
Expert 2885 points
Part Number: DP83TG720S-Q1

Hi，

The customer found abnormal MDIO communication using the RGMII interface of ARM. They can use an oscilloscope to test the MDC and MDO signals sent by ARM, but cannot see the MDIO response signal of the chip. Please help analyze.

Thanks！

  • 0
    Expert 2885 points

    The schematic diagram is attached；

    T1_TEST.pdf

  • 0 in reply to jeno.zhang
    TI__Mastermind 27122 points

    Hi Jeno,

    Please share the waveforms of MDC and MDIO. 

    Would like to perform a few simple checks to first verify the chip is on and functioning. Please probe the RXCLK pin to see if there is a 125Mhz signal. We can also check the CLKOUT pin and RESET pin to ensure the device is not being held in reset.

    Is any other functionality working about the PHY? For example, is link up? Can you transfer data?

    In the schematic, i noticed there is a 2.2kohm pullup on the MDC signal. This should not be placed, the pullup is only needed on the MDIO line. Please depopulate R43.

    Thanks,

    David