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DP83869HM: DP83869 is not working properly in 10/100MBPS

Ram Adhikari
Prodigy 10 points

Part Number: DP83869HM
Other Parts Discussed in Thread: DP83869

 

Hi Team,

In our design, we are using the DP83869 Ethernet PHY with the STM32MP257 processor in RGMII-to-copper mode. We are currently facing the following issues in 10/100 Mbps operation:

  1. 100 Mbps Link Failure in Forced Mode

    • The link is not established when the PHY is configured for forced 100 Mbps operation.

  2. Ping Test Failure

    • Network communication fails, and ping requests do not receive a response.

  3. MII Loopback Test Failure

    • The MII loopback test is not functioning as expected.

Interestingly, the design operates correctly at 1 Gbps:

  • Link establishment is successful.

  • Data transmission and reception work properly.

  • Ping tests pass successfully.

Additionally, from the link partner side, a 10/100 Mbps link indication is observed, but communication is still not functional.

The MII loopback configuration used for testing is shown below:

void mii_loopback(uint8_t phy)
{
    mdio_write_c22(phy, 0x00, 0x8000);   // Reset PHY
    valid_delay_ms(1000);

    mdio_write_c22(phy, 0x00, 0x6100);   // Force 100 Mbps, Full Duplex, Loopback Enable, Auto-Negotiation Disable
    mdio_write_c22(phy, 0x16, 0x0040);
}

Since Gigabit operation is fully functional while 10/100 Mbps operation fails, we would appreciate guidance on possible causes and recommended debug steps.

Thanks & Regards,
Ram