howto add POE to ethernet shield with Ag9120-S


I’m hoping to add POE capability to a ethernet shield with a Ag9120-S module ( - but cant find any arduino specific instructions on how to.

Is it just a matter of soldering the module onto the board - is anything else required ? On the datasheet they mention the voltage provided is selectable (9V - 13.5V) - does anyone know if the ethernet shield sets this on the module ?


Looking at the Silvertel data sheet, it looks as if the voltage adjustment is achieved by connecting a pull-up or pull-down resistor to the ADJ pin. I have no experience of using that module, but the data sheet appears to include a recommended layout for incorporating the module into an Ethernet adapter. Whether it would be feasible to add this on to an adapter which was not designed to incorporate it, I have no idea.

I think the ethernet shield has been designed to incorporate the module - there are solder pads that AFAIK are specifically for this module - the sort of thing I want to know is: does the ethernet shield layout pull up the ADJ pin for me (I think thats how you get 9volts), or do I have to do it myself. As both products (the shield and the module) are (were) sold here, I was hoping someone knew exactly what was involved.


I don't know the answer to that, but if you have the shield in front of you then you could see what connection it makes to the ADJ pin and then investigate to see whether that acts as a pull-up or pull-down. Since this is a simple resistance you ought to be able to measure it directly with everything disconnected and powered down. If as you say there is provision on the adapter for this unit to be added then I'd expect the adapter to provide everything that was needed, or at least provide a very obvious place where you were expected to add any additional supporting components that it needed.