CC1101 changing frequency from 868 to 433MHz - ESP32

Question

I bought a CC1101 module to make a remote for my gate. Unfortunately, the module is marked 868MHz, while the gate needs 433.42MHz. I thought it's changeable, so in code you just set the frequency and done, as it says in the specification. I am not sure why there's a "center" frequency on that module. Does it depend on something other than code?

I was trying to receive a message from a previous remote for the gate I had, but no luck. Only what happens (sometimes, depends on actual code) is that a builtin LED lights up on the ESP32 when I press a button on that remote, but no message appears in serial. I'm pretty sure the wiring is ok, or at least software says it. Unfortunately I don't have an oscilloscope to verify if that the module can send anything on that frequency.

I'm using this library, and this module I expanded the antenna a little.

Sorry if I made a "critical mistake", but I'm a newbie in that matter, just please tell me if I'm doing something wrong, and a potential way to fix it.

Answer 1

Since the matching network (Green inductors and capacitors at the device's RF port) is discrete, you can change these parts to match to 433MHz. Check the reference design for exact values. The antenna should be roughly twice longer for the 433MHz band.

Answer 2

Modern RFIC parts with built-in power amplifiers for the Tx path (you'll only have a simplex Tx in case of garage door opener) need to be matched with passive components depending on topology but also on frequency band. You could check the manual/app notes for this part to see if they mention "PA matching" and if it's sufficient to just replace component values.

You also need to change the antenna.

Answer 3

I experimented with the exact same radio boards, and i also tried to make the transceiver chip switch from 868 to 433 MHz momentarily (after reading that was possible with the CC1101). I used FHEM and CUL software, but unfortunately was never able to actually make it work, though documentation mentioned that should be possible (not optimal of course). I see you have a 433 antenna connected to your 868 board: good. Tried that too (first thing). No luck. It's best to buy a true 433 MHz radio from Ali. Those are cheap too.