MIMXRT1189 interface

sunney79 — Thu, 18 Sep 2025 11:49:31 GMT

hi, we are planning to use MIMXRT1189CVM8C for one of the applications where 3 MII interfaces are required.

I have chosen all 3 MII interfaces on TSN fabric and using iMX pin config tool MCUXpresso Config tool ver 25.6.

1. ETH2 and ETH3 for 2 PHYs, want to use shared MDIO/MDC for these 2 PHYs

2. ETH1 for another MII based PHY, here dedicated MDIO/MDC is preferred.

Now as per config tool, ETH2 and ETH3 both have MDIO/MDC signals but ETH0 and ETH1 don't.

First of all, can I share MDIO/MDC as mentioned in point 1 & 2.

Second, on ETH1, CRS and COL signals are getting omitted if I chose one MDIO/MDC pair to be used, now these signals are required if HALF duplex operation is needed.

Can you please help with correct interfacing scheme here.

Thanks

Re: MIMXRT1189 interface

Omar_Anguiano — Mon, 22 Sep 2025 18:24:31 GMT

Yes, MDIO/MDC can be shared.

If the MCUXpresso Config Tool doesn’t show MDIO/MDC for ETH1, it’s likely due to pin-muxing limitations. AN14251 confirms that not all ENET instances have dedicated MDIO/MDC pins, and sometimes you must share the bus or use alternate pin functions
These are the CRS and COL signals for ETH1:

BR,
Omar

topic MIMXRT1189 interface in MCX Microcontrollers

MIMXRT1189 interface

Re: MIMXRT1189 interface