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How to generate MDC clock?

Associate II

Hi team thanks for your coperation with me.

I have been trying to enable MDIO peripheral

At one of the STM32 EVK kit(NUCLEO-H7A3ZI). What i could see, when i have gone through the MDIO's official block diagram. The MDC pin drew as input and MDIO as bi directional. The following questions are given below.

I know master should be driven the MDC clock. In my case, isn't the nucleo-h7a3ziMDIO slave?

Why we require MDIO Slave in the stm32 products. I think, we require only MDIO Master. Am i correct?

Could you please find my attachments?



Chief II

Well, someone needs a slave interface. So what? A master MDIO interface is implemented as a part of the Ethernet peripheral.

P.S. Why did you added all available tags to the topic? Remove the irrelevant ones!

ST Employee

Hello @Msams.1 @Piranha 

The MDIOS peripheral in our MCU serves as a slave interface to a MDIO bus. As said in the reference manual, A MDIO master can use the MDC/MDIO lines to write and read 32 16-bit MDIOS registers, which are held in the MDIOS. These MDIOS registers are managed by the firmware. This allows the MDIO master to configure the application running on the STM32 and get status information from it. For the MDIO master, we can find it implemented in the  ETHERNET peripheral for PHY device configuration and management as Said @Piranha

PS: this product does not support ETHERNET so we don't have any MDIO Master.

Best Regards.


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