Colibri imx8x with KSZ8873RLL

I connected Microchip ethernet switch RSZ8873RLL to Colibri iMX8X RMII interface. Via Wireshark I can see the Colibri/ethernet switch transmitting and wireshark indicates that a reply is being sent back to ethernet switch/Colibri. It does not appear the Colibri is setup properly to receive. The RXER pin on the Colibri is tied to ground since the KSZ8873 does not have an output to connect to RXER on the Colibri. Aside from setting up the Colibri muxing to the correct alternate function for RMII is there anything else that needs set up for the Colibri iMX8X?

Any other ideas on why I cant receive?

There does appear to be a valid signal coming out of the ethernet switch to Colibri receive pins.

Have you solved this issue? If not - please share your schematic for KSZ8873RLL connection.

I have not resolved issue, attalink textched show connections between Colibri and 8873. Thanks

I’m sorry but provided schematic is not very readable? Do you have a better one?

link text

Your schematic doesn’t look correct. Many RSZ8873RLL pins left unconnected including MDC/MDIO. I’d recommend to use Microchip Design Check Online Design Review Services to verify your schematic.

I only showed the section of the 8873 that connected to the Colibri just to insure there were no issues there. I do have MDC/MDIO connected but its not on the schematic i sent you. I did send the entire schematic to Microchip for their review. You don’t need to have MDC/MDIO anyway.

Transmitting works when i ping from the Colibri linux terminal, i can see data via wireshark, the unit being pinged replies back. Using a scope I can see data going into the receive pins of the Colibri from the 8873 but for whatever reason the Colibri is not registering the data. Could it be a pin MUX issue with any of the receive pins or the reference clock? Is there anything else that needs initiallized on the Colibri for the RMII interface to work? Thanks,I only showed the RMII section of the 8873 that connected to the Colibri just to insure there were no issues there. I do have MDC/MDIO connected but its not on the schematic i sent you. I did send the entire schematic to Microchip for their review.

Transmitting works when i ping from the Colibri linux terminal, i can see data via wireshark. Using a scope I can see data going into the receive pins of the Colibri from the 8873 but for whatever reason the Colibri is not registering the data. Could it be a pin MUX issue with any of the receive pins or the reference clock? Is there anything else that needs initiallized on the Colibri for the RMII interface to work? Thanks

I consulted with Microchip on the issue i’m having with the 8873RLL interfacing with the Colibri imx8x.

For RMII mode, CRS_DV is a mandatory interface. Does pin 50 on the Colibri imx8x serve as RMII_CRS_DV? If so, what ALT mode do I set for pin 50, is it ALT 3?

If so, the Colibri documentation needs clarification to indicate this, there is no mention of pin 50 being used for RMII_CRS_DV in RMII mode(on the documentation I have anyway)

Yes, X1 pin 50 serves as a RMII_CRS_DV. Yes its ALT3 mode