I have a remote for my kitchen fan where I can turn on the fan and light. I want to sniff the signal for the light toggle so I can use my Raspberry Pi 3 B+ to send the signal.

I bought a 433MHz receiver and transmitter and hooked it up to the Pi like this: enter image description here

I took the picture from another forum post. I don't have the transmitter connected yet though.

When I try to run RFSniffer or rpi-rf_receive as root on gpio 27 and have the remote right up to the receiver and push a button I don't get anything at all. I have tried to change the pins any way I can think of but no change. I'm starting to think if it's the remote that doesn't really send on 433MHz? Although it says so on the back.

enter image description here

What can be the problem here?

Some forums posts says I need to use resistors so I don't send out 5V on the gpio pins but most of then just connect them like the picture above so I don't know what to do.

  • @jsotola I don't have the transmitter connected as I said in my first post. – PatricF Jan 7 at 18:46
  • @jsotola - I think he meant "the question" ... I took the picture from another forum post. I don't have the transmitter connected yet though – Jaromanda X Jan 7 at 21:52
  • I bought a new receiver and transmitter from a different brand but that didn't work either. I can't sniff the signal from the remote so I scrapped this idea. Instead I'm going to use the remote and solder on a optocoupler instead of a button and trigger it from the GPIO pins instead. – PatricF Jan 14 at 19:37
  • I found this article which showed me the receiver works where the "RFsniffer" comes up with nothing instructables.com/id/… – Frans Jan 31 at 10:07

The frequency does not tell you how the signal is modulated.
The parts you show work with amplitude shift keying (ASK) or more precisely on/off keying (OOK) in such cheap devices. But there are other methods of modulation like frequency shift keying (FSK) and variants thereof. So the frequency alone is not enough to get interoperability.
In most cases the cheap OOK is used but it is not guaranteed to do that.

You would need something like an SDR to check the frequency and modulation.
This sounds more complicated that it really is and not as expensive. All you need is a USB DVB-T receiver with a specific chip RTL2832U like this one from china. And a free software like GQRX.
With this tools at hand you can easily debug 433MHz devices.

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