STM32H735G-DK: RGMII Ethernet interface with RX_ERR?

[HMüll.4]

Hi,

when looking into the schematics of the STM32H735G-DK board (MB1520B), the Ethernet-PHY is connected via RMII.

Now when I configure RMII for an STM32H7 in CubeMX, the interface pins do fit properly to what is used in the MB1520B schematics - except the RX_ERR-line. According to the schematics it is connected to PB10, but when I enable PB10 in CubeMX for use as RX_ERR, it is marked in yellow with the remark "no mode".

So...how do fit both things together? How can I enable RX_ERR being used in Cube MX for RMII-mode?

Thanks!

 

[LCE]

Check the datasheet for the alternate functions, I faintly remember that RX_ERR is simply not supported by the H7 hardware. But I might be wrong.

And it's definitely RMII, without the "G". ;)

[HMüll.4]

So this would be an error in the evaluation board from ST then!?

[LCE]

Not an error! You could still set the GPIO to interrupt mode, or poll it.

Anyway, Cube is not perfect...

Edit: found it in the datasheet!

But the H7 ETH-peripheral's RMII doesn't do anything with that pin, except that it sets a bit in an RX descriptor.

Still not sure if that's the case for MII or RMII, in the datasheet it's called only " MII_RX_ER ", all RMII signals are usually called " RMII_* ".

Is the signal connected to the PHY ?