Has anyone done or come across a more or less straightforward way to connect something small like an Arduino Pro Mini to an ethernet connection? Whether it's to a breakout board or other similar method of getting it talking to the network. Extra points if you can point me in the direction of doing it using PoE as well....
What I'm trying to do is build a small device that can be connected to the LAN (wires are not a problem) which lights up a little metal / glass brick when an action occurs. Obviously size is the main factor here as I have some really natty little containers to use but there's no way I can squeeze in a full sized arduino + ethernet shield. In fact the containers are so small even a freetronics EtherTen (ethernet + uno on the same board) won't fit in with the other light elements I need to put in there.
Thanks CrossRoads, that's looking quite interesting and uses the same module as all the ethernet shields are built from so libraries will be a doddle once it's connected. Consistent 3.3V as well means this should work quite nicely.
Now if I could get a PoE one that does the same thing I'd be laughing as there'd be no need for separate power supply or batteries....
You didn't say how many output/inputs you are using but, a cat5 has 8 wires in it and you could have an Arduino remotely located and use the cat5 to transmit the power to your device. You could have and Arduino as the center of a few modules and cat5 running to each.
Yep well standard ethernet only uses I think 4 or 6 of the 8 wires in cat 5 - I guess I could supply the power from a PoE switch or injector then splice the cat 5, taking whatever is needed network wise through the wiznet for Ethernet connection then use the powerline pair to juice the arduino... that might work. Would be relatively easy to test as I have a PoE injector and I could splice some cat5 easy enough to see if I can continue to get a decent network connection without the power pairs easily enough.
Power over Ethernet - makes use of the spare lines in cat 5 to give you up to I think 48V of power. Pretty cool stuff actually - we have all our phones at work powered and networked with only a single cable and I've really taken to it as a result of playing with the Freetronics EtherTens (An Uno + Ethernet shield + PoE onboard so no need for batteries or wall plugs!) as often I'm happy to go with a network cable as WiFi is still a bit expensive and patchy with Arduino for quick projects.
If you could do that with a pro mini I'd have all sorts of very tiny network pluggable devices (network points I have plenty of, it's power I'm short on).
I actually need to check that because I'm not sure how the voltage is set coming from the PoE switch but I know it can vary based on the device. Irrespective; for the first version I'm going to use a PoE injector which outputs a nice even 9v so presumably a simple voltage regulator should be sufficient to drop that down to 3.3v - I haven't used the pro mini before so not really had to play with regulated 3.3v with an Arduino.
ajfisher:
I actually need to check that because I'm not sure how the voltage is set coming from the PoE switch but I know it can vary based on the device.
If it's an 802.3af-compliant PoE switch, it's 48V, but it won't supply power to just anything. You need a PD circuit to let the switch know that there's a compliant device at the receiving end before the switch will attempt to supply full power.
You either need something like this, or make something equivalent from the 802.3af spec.