TJA1103 in RMII or RMII-clkmode does not transmit data

[MJDSys]

We have a TJA1103 Phy we are trying to use on an NXP evaluation board (the X-S32X-MB).  We are trying to use it in either RMII or RMII-clkmode, using an external 50MHz reference clock located on the daughter card.  However, when we enable RMII-clkmode (through pin strapping or MDIO) or RMII (only through MDIO, pin strapping doesn't seem to work), we do not observe any ethernet traffic.  Leaving the PHY in rev-RMII, we can observe some traffic but we notice a significant number of dropped packet, which we believe is caused by the two clocks fighting each other (we can not easily disable the external reference clock).

Note: We do enable Autonomous mode in the phy over MDIO, to have it connect to our automotive ethernet switch.

Are there any other steps we need to take to configure the PHY to work in RMII or RMII-clkmode?  We can see the 50MHz clock being generated on the daughter card.

Thanks,

Matthew

[MJDSys]

Hi Peter,

The PHY on the board is a TJA1103 (the X-S32X-MB), talking to a S32K396 chip with an EMAC MAC, using RMII.  We are using development boards from NXP, so I assume the PCB has been designed/manufactured to appropriate standards.  I'm happy to answer any questions you have about our setup, but we are trying to stay close to the default settings of the boards.  If it would help, I'm happy to send you any relevant parts of the S32DS project.

Is there a problem with using RMII/RMII-clkmode with this combination?  We were looking to avoid using rev-RMII as our other setups are not using it, and we want to avoid differences.

I did read through the DS previously, and also checked out the AN.  AFAICT, we are following all the recommended steps but we still see the packet loss.

Thanks,

Matthew

[PetrS]

Hi,

so you have S32K396 daughtercard connected to motherboard (XS32K396-BGA-DC + X-S32X-MB) and want to try motherboard's PHY interface for communication.
If I am right, could you please share a boards revision you have?
Not sure of ready example for this, there should be some for daughtercard and TJA1101B sabre board. But let me try to get any.

BR, Petr

[PetrS]

Hi,

from the description it is not completely clear which boards are used, what is the MAC-PHY connection done, etc. Try to specify it more.
Generally, the device DS and associated APP note describe device connection in rev-RMII mode, the pins strapping needed for PHY configuration, etc. Documents are given under Secure Files section on its web page

BR, Petr