RMII MII Help Please

Sep 03, 2008 1 Replies
B

Note: I also posted this to c.a.embedded. I'm not sure it belongs here, but no answers there so far...



In putting together a little control nodule w/ a single 10/100 ethernet port, I started wondering if I need to pay any attention to the RMII. IIRC (& it seems that there is not much that I do anymore), I built some working 10Mbit - realtek based - boards w/o ever paying any attention to RMII.



However, somewhere I read that this spec defines communications between the MAC & the PHY.



Again, using the realtek (8019as) chip (or even national chips) reads & writes occurred over DMA between the chips & a PIC. Do I have to pay attention to RMII only on multiple (hub or switch) eth port configurations or always? If someone can clear this up for me, I'd appreciate it.



Thanks, Tom


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M

Tom, It's not clear what you are trying to do from your post.

RMII is a way to connect a PHY chip to MAC chip. You only need to worry about RMII if you are doing a PCB layout. You need to choose a MAC and PHY chip that both support the same MAC/PHY interface. For 10/100 this can be MII, RMII or SMII. So if both your MAC and PHY chip support RMII you simply connect the relevant pins together on your PCB.

Arthur.

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