Multiple ethernet shields


would it be possible to stack multiple ethernet shields on the same microcontroller?



Probably not. Certainly the official shield uses fixed I/O pins which would conflict if you stuck two of them on. It begs the question why you would want to ?. An Arduino is a slow creature with limited resources, hardly worthy of being a multi-homed device, surely theres another way of doing what you want to do away from the arduino ? (router perhaps ?).

Hi Pluggy,

I can see why your wondering.
I actually plan to use the Arduino as part of a device to switch in between two nodes of an Asterisk pbx. Both nodes communicate via a dedicated line to the Arduino which in turn by means of a relay-card will connect the telco line to one or the other node.
On the Asterisk nodes there is cluster software running - if a node becomes master it will tell the arduino via the network connection to switch the telco line to this node.
Theoretically I could use a switch or hub for this, but this adds a new single point of failure, something you want to get away from in a cluster setup.

I could always use two Arduinos, but as far as ease of configuration is concerned, this is not ideal.

What if I would use different I/O pins for the second shield? Would the library allow this? I'm not really familiar with Arduino yet, hence my question.

Thank you!

The official shield isn't configurable. I've perused the schematic of the unofficial ENC28J60 ethernet board which I haven't used and it appears to use fixed digital Pins 2 and 12. Since the official one uses 12 it would appear that using an official (Wiznet) and an unofficial one together won't work directly either. No doubt some hacking in software and with a soldering iron might change the state of affairs. A further problem is that the ENC28j60 library is a tad on the meaty side so you might be struggling with resources (a 328 arduino rather than a 168 would be a big help).

Hmmm ... i see ...

well considering it's limited pricing, I guess there's something to be said for just buying two pairs of these things.

Thanks a lot for your research!