Re: Ethernet daisy chaining

On Mon, 28 May 2007 21:27:36 GMT, "Al Williams"
<donotreplydirect@xxxxxxxxxxxxxxxx> wrote:

I read this in Wikipedia near the end of the RMII docs:
http://en.wikipedia.org/wiki/RMII

"Since the RMII standard neglected to stipulate that TX_EN should only be
sampled on alternate clock cycles, it is not symmetric with CRS_DV and two
RMII PHY devices cannot be connected back to back to form a repeater; this
is possible, however, with the National DP83848 which supplies the decoded
RX_DV as a supplemental signal in RMII mode [3]."

It seems to imply you can create a simple repeater with two PHY's "back to
back" in MII mode. This would be useful for a new device we are working on
that needs to daisy chain its Ethernet in and out. I can't find much info
on how to do this, anyone done this and if so, how?

Thanks.

AFAIK it should be possible - from what I can tell that is what dumb
ethernet hubs do anyway.
See http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm for a
simple 3 port ethernet hub schematic.
--
Brendan Gillatt
www.brendangillatt.co.uk
GPG: 0x6E265E61
.