RF Decoding/capturing

Hi all,

I'm new to Arduino, and so far finding it extremely interesting! My plan is to build home automation.

For my project, i'm wanting to start by being able to control my heating system with the Arduino.

I've got myself a 433MHz receiver and transmitter, however I haven't been able to 'capture' the RF being sent from my usual RF thermostat (I have however successfully captured the RF from various non-make remotes).

From my understanding, I haven't been able to 'capture' the RF signal I need due to the signal being encoded (I've been using RC Switch).

My question is; what would be the best method of capturing/decoding the thermostat signals?

If it's any use, the RF thermostat I have is a Honewell CM61NG, and it's 433MHz.

I use the techniques described in this blog post to decode RF sensors.

Thanks for the reply and link bud! It's helped me out a lot - however I've ran into a problem, and hoping someone might be able to help.

From your link, it seems the majority of people are using RF receivers with 8 pins, my receiver only has the 4 pins, so I've tried to improvise.

I've built the circuit in the below pic, however when I'm connecting it to the Line-In (not mic), i'm not picking up anything within Audacity - just a blank line. I've tried multiple RF remotes, and nothing is being picked up.

I've made sure my settings in Audacity are 48000hz and mono.
The RF receiver does work, as I used it with RCSwitch to pickup an unencoded signal.

Any hints or tips? Does my wiring look correct below?

Oh, I also didn't have any 39k resistors, so instead I put 3x 10k's and 2x 4.7k's in series - not sure if this would have any negative impact?

Does my wiring look correct below?

Impossible to know from that picture. Post a clear photo of a pencil-and-paper drawing showing all the connections and parts, labeled with pin names and numbers, like this:

Sorry for the delay getting back to you, I'm quite new to the whole thing so decided to make a diagram to show you how I've put it together, hope it makes sense.

Things to note:

The 'Ping' chip shown in the diagram is where I have my RF receiver, so ignore the incorrectly marked pins. For the Ping chip shown (which is the RF receiver), the left pin is +5V, middle pin data, and right pin GND.

The power source i'm using is just the Arduino (no code, only using the +5V and GND).

The Audio jack I cut up has one white wire (to GND as in the image), two green wires which I've wrapped together (to just below the small blue bridge shown in image), and one red wire (also connected to below the blue bridge shown in image).

Click to enlarge.

Oh, not sure if it helps - but for reference this is what I'm 'attempting' to make:


Managed to get it working, stupid mistake on my part - I had the audio grounds connected to data, and the left audio connected to ground. Also swapped the resistor series out for a 39k i picked up and now reading signals!

Although the thermostat actually runs on the 868MHz band, not 433 like I thought. So ordered a 868MHz transceiver.

If your likely to do other RF decoding things in the future then I would suggest buying something like this and use it with free SDR software (maybe this). They are great for finding the frequency of unknown transmitters and recording the signal.

Thanks Riva, that's really interesting! Didn't know it was possible to use one of those :slight_smile: