Hardware connections for an IMXRT1176 for RMII

[b2che]

Dear community,

we are working on a hardware design using an IMXRT1176 and would like to connect 10/100 Ethernet to an Ethernet PHY.

It seems there are two peripheral blocks which can be used within the device: ENET or "ENET 1G".

We want to connect the Phy using RMII.

My question is: can we use the "ENET 1G" block and only connect the RMII signals (connecting these to the signal shown for the instance ENET 1G on p.377 of the reference manual)? This would be preferable for signal multiplexing reasons (some of the signals going to ENET are in use for other peripherals).

Thanks for any help you can give!

[b2che]

Hi Omar,

OK, thanks for the tip!

One follow up: I am used to using a wire called CRS_DV for my RMII wiring, for signaling the start of receive data. However the ENET 1G (also the ENET) has 2 signals: CRS and RX_EN. Which of these should I wire to CRS_DV?

Kind regards

[Omar_Anguiano]

You may use RX_EN. You can use the EVK schematics as a reference.

If you have more questions do not hesitate to ask me.
Best regards,
Omar

[nilsl]

I have a very related question: The custom IMXRT1176 processor board of my customer for 10/100 Ethernet has the RMII PHY wired to the ENET_1G_xxxx-pins.
Our planned development framework (Zephyr) unfortunatly does not seem to support the ENET_1G MAC of IMXRT1176 yet, only the 10/100 one. Is it possible to use the ENET MAC (10/100) of the CPU even though the PHY is connected to the ENET_1G_xxxx-pins? Or is there another suggestion how to get 10/100 Ethernet running with Zephyr?
Best regards, Nils

[Omar_Anguiano]

Hello!
Hope you are well.

ENET1G interface is compatible with RMII.

If you have more questions do not hesitate to ask me.
Best regards,
Omar