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Unable to read PHY identification Number in TJA1100 ETH PHY

Question asked by channakeshava Siriyanna on Oct 11, 2019
Latest reply on Oct 22, 2019 by bpe

Hello All,

We are using tja1100 ETH PHY for BroadReach ETH communication, 

Connection is as follows:

Microcontroller is connected to TJA1100 via RMII.

PHY is controlled by uc using MDIO, MDC PINs.


The following configuration are made for PHY:

Config0: LOW (Configured as Slave)

Config1: LOW (Managed operation)

Config2: LOW

Config3: HIGH

So, RMII mode (25MHz)

and uc is configured with all required port pin settings.


Problem: Could not establish connection with PHY through RMII. so PHY ID also could not be read.

Whether MDC clock will affect communication with PHY?


Thank you.