Homebuilt sensor with rfxtrx433

[lagerberg]

Hi,
Sorry for the "double posting" - I have more or less asked a similar question elsewhere. I feel that this might be of general interest though:
I would like to measure current consumption for my heat pump. I have the pieces to build my own sensor, with an AtTiny85 (and a current transformer) doing the work.
I wish to send the measures via a 433Mhz transmitter, using preferably the Oregon v3 protocol.
To test this, I have made a fake transmission, showing temperature data from my AtTiny, and this gets picked up by my RrxTrx433.

The next step is to have this show up as power readings (and not temperature) in RfxTrx433 / Domoticz.

I have a hard time, however, to find details on what data to send to emulate a CMR119 or other type of OWL sensor.
Can anyone point me in a direction where I can find this? I have googled several hours, but cannot find what I am looking for.
On the other hand I suspect that the answer is right under my nose in the open source implementations of the rfxtrx and other units, if I just knew where to look...