Why 2 wifi cards on emonTX?

I am trying to get my head around how all this hangs together and I am confused (doesn't take much tbh!).

I have bought the emonTX Shield and a RFM69CW. The thing is that in a couple of places in the various pages of documentation there are pics of the shield on the back of an Arduino/nanodeRF with a RFM module on the Arduino board as well as one on the emonTX Shield.

Does it need 2 Wifi boards? What is the function of each? I can't find this info anywhere... perhaps I haven't looked hard enough! :)

I haven't yet bought the Arduino onto which I will put the shield so before I buy one I would like to know if I must get a nanodeRF or whether I can just run with the RF module on the shield.

If there is documentation that explains this then I apologise, I missed it (not through lack of searching I promise you).

Robert Wall's picture

Re: Why 2 wifi cards on emonTX?

I'm no Arduino expert, however the usual set-up is to use the emonTx Shield on an Arduino. The RFM69CW is not WiFi, so the Arduino may well be using WiFi to connect to the router rather than using a wired Ethernet connection, bypassing the Base Node in the usual Sensor Node -> Base Node -> emonCMS set-up.

Without knowing the exact context of what you've seen, it's pretty hard to guess what was going on, as the system is so flexible, it could have been pretty much anything.

What is the overall set-up that you're putting together?

SnaxMuppet's picture

Re: Why 2 wifi cards on emonTX?

Ah yes... I have completely disconnected the fact that the RFM69CW is not Wifi. How could I have done that!!!

Now it makes sense... the RFM69CW on the shield is to communicate with the emonBase and potentially other 433/868 (depending on which you have) devices and the nanodeRF would then have Wifi capability to talk to the wifi network if that is needed.

Got it!

I suppose, if you don't have any special requirements for wifi then I can just use a Arduino Uno and the shield will just send the data to the emonBase via the RFM69CW over 433/868 and the emonBase will then connect to the network/internet to log the data.

Many thanks for explaining... told you I got confused easily! :)

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