emonTX with Arduino + RF12B

Submitted by Guest on Wed, 01/05/2013 - 02:06

Hey guys,

I'm working on using the emonTX for one of my projects and I'm having problems getting communication going. So far, I'm looking to have the emonTX transmit its readings to a custom Arduino module with an RF12B module taken from an emonTX kit. I've had the second arduino setup from following this page: http://openenergymonitor.org/emon/buildingblocks/rfm12b-wireless

and I've tried loading up the sample code for Tx and Rx to the emonTx and the Arduino respectively. So far, the Arduino reports that its received something from the rf12_recvDone() function, but then it doesn't follow through. This is the first time I've tried wireless comms so I'm pretty lost on what could be wrong. I've followed the NodeID, Network Group, frequency and data structure and I still don't know what could be wrong.

I'd really appreciate any help.

Cheers :)

Re: emonTX with Arduino + RF12B

Submitted by Robert Wall on Wed, 01/05/2013 - 10:02.

The emonTx will (unsurprisingly) receive. Here's a test sketch that might help you. You could well need to change I/O pins if you've connected to different processor pins on the Arduino.

Re: emonTX with Arduino + RF12B

Submitted by sloth (not verified) on Fri, 03/05/2013 - 00:25.

Hi Robert,

Thanks for your reply. For the Tx sketch, how do I set up the transmission? I've set the Payload to the same as in the test sketch but for the main loop() do I just set emontx.trigger = 'A';?

emontx.trigger = 'A';

int i = 0; while (!rf12_canSend() && i<10) {rf12_recvDone(); i++;}

rf12_sendStart(0, &emontx, sizeof emontx);

Re: emonTX with Arduino + RF12B

Submitted by mharizanov on Fri, 03/05/2013 - 05:56.

I have heard that RFM12B on breadboard may misbehave due to capacitance being introduced by the jumper wires and the breadboard itself. I think you may be better off doing a stripboard shield to plug ontop your arduino.

Re: emonTX with Arduino + RF12B

Submitted by Robert Wall on Fri, 03/05/2013 - 10:08.

That sketch was only a demonstration - the transmitter just sent "A" & "B" alternately to prove something was happening! You must of course substitute a payload that is useful to you. You use the standard emonTx sketch for transmission - and set the parts of Payload with your (useful) data - just as in the standard emonTx sketch. I was using a nanode for the transmitter and emonTx for the receiver, I had absolutely no difficulty but Martin's warning needs to be heeded if your layout is not tightly controlled.

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