Hi there,
I’ve got this doorbell transmitter and receiver i hoped to be able to intercept and send the OOK push button to Home Assistant. So my setup is a Lilygo TTGO Lora32 v2.1 433/470 and the doorbell transmitter is a generic doorbell (known under many names) with a EM2521-TX board and an CMT2150A chip. It is listed everywhere i could find as a 433.92 MHz transmitter but OMG can’t detect anything. I use the lilygo-rtl_433 environment, of course the device is not supported but wouldn’t i be able to get raw data…? It’s also possible that it could be rolling code but at least i would be able to catch at least something. I tested different RF frequencies in the OMG webUI and i am indeed catching stuff from the neighborhood, but not my doorbell… Am i missing something here or maybe my info about the doorbell is wrong but i suppose that a doorbell will be in a frequency range supported by the Lilygo board…? Any help would be appreciated…
Welcome @deltagreen88
The only doorbell decoder in the rtl_433_ESP library I can see is the Honeywell ActivLink, Wireless Doorbell in its OOK and FSK version.
So it is probably very likely that the rtl_433 protocol on a LilyGo board is the wrong way to try and received your doorbell signals.
The alternative possibilities would be an ESP8266 or ESP32 with an SRX882 receiver, for testing the three protocols RF(RCSwitch), RF2(KaKu) and Pilight, as described on the RF Setup page.
While there is no guarantee that any of these three protocols will actually work to properly pick up your doorbell, especially if it is using rolling codes, it really is the only way to give it a try with this kind of setup.
I hope this helps.
Hey, thanks for your reply
Do you think loading an environment like esp32dev-pilight (apparently it doesn’t require a CC1101) would be possible to test the Pilight library on the Lilygo…?
EDIT: Tried that, doesn’t help 
I think i’m at a loss here, the Lilygo doesn’t seem to be the right hardware for this…
Is there a way eventually to find out at what frequency the doorbell is emitting and than somehow get a raw signal with a code (assuming it’s not rolling code or at least a limited number of codes)…?
I agree there, as your device doesn’t seem to be an rtl_433 decibel RF device.
Your best bet really is to try with an ESP8266/ESP32 and an SRX882 receiver connected and the three different protocols. Doesn’t really help your specific case, but all my non-rtl_433 devices nicely fall into the RF(RCSwitch) protocol.
Testing with the CC1101 and Pilight, did you make sure you were close to the sender, as CC1101s often do not have a very long reception range? Just to fully rule out Pilight 
Also with an SRX882 receiver and these three libraries, they are usually not as finicky with the exact frequency as rtl_433 can be, especially with FSK in the 868MHz band.
I don’t have a CC1101, i used the Pilight environment that didn’t require it, but still to no avail. Just to try, but without much hope, i’m going to get a NodeMCU ESP32 and the SRX882 receiver an will try this out.
Another thing i could try would be to intercept the doorbell’s receiver unit’s buzzer signal with a shelly and make that trigger actions. Completely different approach but i think there’s just a lack of support for RF codes/devices in general.
I misread you above when you mentioned a CC11201 , but no, any Pilight environment would not have worked on the LilyGo alone with its built in receiver. So best to also properly test Pilight again once you have your ESP32/SRX882 combo.
I’m actually doing something similar with the buzzer in my intercom unit, with the innards of a repurposed magnetic contact sensor taped to the buzzer coil 
Uh yeah, i thought of that for my main doorbell-gong combo, i bought a reolink doorbell cam that of course wouldn’t trigger the existing mechanical gong so i wired a shelly to the gong and trigger that with the push of the camera’s button. Works instantly, and i even trigger a couple of other actions like this. Now this doorbell is just a dumb one further away and the ultimate aim is to trigger the gong the same way through the shelly. But for that i need a way to intercept the button push, either through rf signal interception or electrical signal interception with the existing receiver that came with that doorbell… We’ll see, i ordered the chips today to further test the rf side of things, otherwise with a shelly uni - that i’ll have to understand first, but i think it’s always good to have and tinker with it…
Fingers crossed that one of the three protocols will recognise it correctly with the SRX882.
Ok, so i purchased the ESP32 38pin board that i have some trouble identifying (USB-C). Plus i don’t really know how to wire to a SRX882 (and a STX882) module. I connected the G27 to the DATA of the RX and the G12 to the DATA of the TX, GND to - and VCC to + but am not able to get anything