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MAC/MDIO Issues with STM32H7 Emcraft SOM


Hi STM32 Community,

I'm using a SoM with the STM32H750, made by Emcraft. My goal is to set up Ethernet using the standard HAL library alongside lwIP. However, I've hit a snag with the MDIO communication to the PHY(a Waveshare LAN8720 board).

Based on the oscilloscope outputs (attached), the MAC isn't producing the expected signals for the MDC and MDIO pins during an MDIO read, but the busy bit(MB) is still cleared..


To diagnose the issue, I've:

  • Checked the PHY's reference clock.
  • Reviewed all GPIO settings.
  • Confirmed the MDIO clock configuration.
  • Checked my code thoroughly.

I have a few questions:

  1. Has anyone faced a similar issue?
  2. Is there a configuration step I might have missed?
  3. Could my soldering work on the board jumpers have caused damage?

Any advice or suggestions would be appreciated. Thanks!

Regards, Thomas Schöller