interfacing RMII and configuring its clock

surendersampath · ‎2024-11-21

I'm trying to get the ethernet initialization work.

I am currently dealing with MX_ETH_Init(); failing in error handler as the software reset is not happening with the phy driver. I believe my clocks are not configured properly as per manual :

As far as I understand, I need generate a clock of 50 Mhz from cpu on the PB6 pin and it should be okay.

I have configured the clock to do the same. Attached the .ioc file as well.

q1. Why does under RCC system core, It shows ETH_RMII_REF_CLK AS DIGITAL INPUT CLOCK?

q2. Is my clock configuration correct? I looked in the datasheet : It says I need to provide 50 Mhz to the driver chip from cpu. If not, the driver should have its 25 Mhz crystal oscillator which is not the option in the nucleo board.

STea · ‎2025-01-15

Hello @surendersampath ,

1- ETH_RMII_REF_CLK is indeed a digital input from the PHY to the Microcontroller which is an input to the Ethernet Peripheral.

2-The Nucleo board has an external 25Mhz oscillator named X4 connected to the PHY XTAL1, XTAL2 inputs, here is the schematics of the board to make it clearer:

Regards

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