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STM32F4 Ethernet PHY connection(MII_CRS pin Issue)

Question asked by Jin Kim on Jan 9, 2018

Hi Everybody Help me.


I want to use it in the following way.

However, Ethernet PHY chip does not have MII_CRS pins. (PHY Chip is RTL8304E)

Do you have to handle the MII_CRS pin of STM32F4?


The MCU Ref. Manual notes:

"MII_CRS: carrier sense is asserted by the PHY when either the transmit or receive
medium is non idle. It shall be deasserted by the PHY when both the transmit and
receive media are idle. The PHY must ensure that the MII_CS signal remains asserted
throughout the duration of a collision condition. This signal is not required to transition
synchronously with respect to the TX and RX clocks. In full duplex mode the state of
this signal is don’t care for the MAC sublayer."


I can not tell what to do with this pin.

1) full up 

2) full dwon

3) RX_DV pin and MII_CRS pins Common connection


Please let me know