Hi,
I recently bought one official Arduino Ethernet Shield, which look exactly like the one in the first post.
As with every new “toy” I buy, I did some research on this new Shield.
These are my findings:
-Ethernet jack, although not documented, seems to be a pretty standard PoE jack with internal magnetics, with no internal rectifiers for PoE. As defined in 802.3af, power can be injected either on pair 7-8 or RX and TX pairs. This jack supports both – pair 7-8 is routed directly to jack’s pins and possibly center taps of RX and TX transformer primary windings are also routed to jack’s pins (V1+, V1- and V2+, V2- in the schematics).
-There are 10 unmarked holes on the PCB, 6 near Ethernet jack and 4 between W5100 and SD socket. Let’s consider first group of holes near the Ethernet jack as pins 1 to 6 (pin 1 is the leftmost, near the edge of the PCB). Pins 1 to 4 are connected to jack, being V1+, V1-, V2+ and V2-. Pins 5 and 6 are unconnected. The second group of 4 pins, say pins 7 to 10 are, in this order, GND, Vin, ADJ and unconnected. ADJ has a 0 Ohm resistor to Vin.
Now get the following datasheet: http://www.silvertel.com/DataSheets/Ag9400v2-3.pdf
This component pins match Ethernet shield PCB, both electrically and mechanically!
It seems this Shield was designed to use a Silvertel Ag9400 POE module!
Further investigation reveals that possibly an Ag9412-2BR is a good choice – This module nominally outputs 12V, but with the 0 Ohm resistor between pins 8 and 9, voltage outputs drops to 9.8 Volts, which is OK to power arduino 5V regulator.
Unfortunately, I don’t have one Ag9412-2BR available at this moment (I only have Ag9403 and Ag9405…) and, although they are very cheap, these modules are not easy to get...
If you have one Ag9412-2BR available, please try it and let us all know your findings!
Regards,
Pedro Couto