Ethernet Design for MII PHY on chipKIT MAX32

Created Thu, 26 Jan 2012 18:15:39 +0000 by mhanuel

mhanuel

Thu, 26 Jan 2012 18:15:39 +0000

Does anybody know the reason that the MAX32 board is designed for use the RMII interface, as stated on the chipKIT reference manual page 10 under the 10/100 Ethernet MAC section.

I was looking at the board pin out and it seems the MII interface pins are all available on headers, could be due to some electrical conflict cause by any signal of the MII interface be used somewhere else?

Actually I found that these signals should be routed differentially and with impedance matching, maybe the MII signal aren´t layout taken that into account?

I will appreciate your comments,

owendelong

Tue, 28 Feb 2012 07:54:35 +0000

My best guess would be that the RMII uses fewer pins creating fewer conflicts with other shields.

As it is, if I'm to port my application over to Max32 from the Arduino Max2560 I've been using, I'll need to do substantial surgery to all of the ethernet code, change the pinout of several things (requiring surgery on 3rd party libraries in some cases) and cut several board traces on the shield.

Regarding this last.. Come on, ChipKit... Are you really so cheap that you couldn't just provide the headers and jumpers for these things up front?

I'd have gladly paid an additional $1 or $2 (should be about $0.25 for the parts in bulk) for the card to have jumpers instead of traces.