EmbDev.net

Forum: µC & Digital Electronics Ethernet cross 1:1


Ethernet cross 1:1
von Dirk (Guest)

Rate this post
• ▲ useful
▼ not useful 
I use ethernet with an AVR32. Connected to a switch with a 1:1 cabel and 
direct to a network-card with a cross-over cabel. Is it possible to 
connect two RJ45, wired 1:1 and cross-over, to a single MAC?
Of course only one connection can be used at a time, but whatever cable 
you have you can connect to whatever port, switch/hub or netword-card.
Does the unused port must be terminated in some way?

Many thanks for your help

Report post Edit Move Thread sperren Anmeldepflicht aktivieren Anpinnen Delete topic Thread mit anderem zusammenführen Quote selected text Reply Reply with quote
Re: Ethernet cross 1:1
von Schrotty (Guest)

Rate this post
• ▲ useful
▼ not useful 
>Is it possible to
>connect two RJ45, wired 1:1 and cross-over, to a single MAC?
No! You cannot connect a RJ45-Jack or Cabel to a MAC. You can connect it 
to a PHY which is connected to a MAC.

Modern ethernet PHY´s support auto-X-over functionality, which 
automatically detects, whether a crossed oder a straight cable is 
connected.

Report post Edit Delete Quote selected text Reply Reply with quote
Re: Ethernet cross 1:1
von Dirk (Guest)

Rate this post
• ▲ useful
▼ not useful 
Thanks for your help.

The phy on my board do not auto-detect the wiring. Only modern 
GigE-cards must have this feature. Old 100Mbit cards do not. OK, if I 
wire two RJ45 with magnetics to my single phy, does the unused wires 
will disturb the wires used? Both RJ45-connectors are still connected to 
the single phy. Do I have to terminate the unused RJ45-connector?
It is only for the convenience of the user. Whatever cable he have and 
to whatever he want to connect the uC, choosing the correct 
RJ45-connector and done.

Report post Edit Delete Quote selected text Reply Reply with quote
Re: Ethernet cross 1:1
von Schrotty (Guest)

Rate this post
• ▲ useful
▼ not useful 
A lot of 100MBit PHYs support auto-x-over! but it´s not a "must", that´s 
true..

You want to attach TWO magnetics and Jacks to ONE PHY?????
That´s (sorry) crap!

If you design your own PCB why don´t you use a simple 100MBit PHY with 
auto-x-over and one Jack
(e.g. 
http://www.micrel.com/page.do?page=product-info/fastether_trans.jsp )

Report post Edit Delete Quote selected text Reply Reply with quote
Watch this topic | Disable multi-page view
Please log in before posting. Registration is free and takes only a minute.
Existing account
Do you have a Google/GoogleMail account? No registration required!
Log in with Google account
No account? Register here.