Would this work with a 915 MHz CC1101 module that has no GDO2?

[melyux]

Current Situation

I got one of these CC1101 modules by Rabbit-Labs that actually supports 915 MHz. I'm going to try to use it for capturing data from 915 MHz frequency protocols (i.e. SCM) that this project supports... sounds great right? This is the only 900 MHz CC1101 board that I've seen out there and looking forward to testing it.

But I see in the pinout that GDO2 doesn't seem to be connected to anything on the board:

PINOUT

1 - GND - Flipper Pin 11

2 - 3v3 - Flipper Pin 9

3 - GD0 - Flipper Pin 6

4 - CS - Flipper Pin 4

5 - SCK - Flipper Pin 5

6 - MOSI - Flipper Pin 2

7 - MISO - Flipper Pin 3

8 - UNUSED - N/A

Would this be a problem for use with rtl_433_esp? Not that I have any other choices when it comes to 900 MHz

Logs

N/A

Configuration

N/A

Environment

N/A

Process Supervisor

not applicable

Additional Context

No response

[NorthernMan54]

Likely, if you have the module, just give it a try

Under the covers I'm using RadioLib, and this is what the docs say about the pins - GDO2 is mapped to gpio

RadioLib

[melyux]

I got it connected and it's receiving. But the SCM decoder doesn't seem to be working properly with this.

The same message that rtl_433 successfully decodes:

{"time" : "2025-11-27T02:08:12", "protocol" : 149, "model" : "ERT-SCM", "id" : 38872474, "physical_tamper" : 0, "ert_type" : 12, "encoder_tamper" : 0, "consumption_data" : 542612, "mic" : "CRC", "mod" : "ASK", "freq" : 914.838, "rssi" : -0.503, "snr" : 36.870, "noise" : -37.373}

rtl_433_esp seems to fail:

02:08:12.817 > rtl_433_ESP(6): Ignored Signal length: 24996, Time since last bit length: 3478, Gap length: 14972947, Signal RSSI: -78, Current RSSI: -81, pulses: 5, noise count: 53

[NorthernMan54]

It only picked up 5 bits of data.......

[melyux]

Huh. If I tune it to 433MHz, it picks up a lot of those sensors even though neither the antenna nor the transceiver is tuned for that frequency

[melyux]

I wrote a standalone PlatformIO program to decode SCM on my ESP32 with the 915 MHz CC1101, and it works great now. I tried to apply it to this project, but it requires changing some of the common settings this project uses (RSSI delta, bandwidth, kbps), and when I did that, I started getting real SCM decodes even with this project.

Unfortunately, it doesn't decode as efficiently as my program (~5 decodes per hour, as opposed to my ~32 decodes per hour) and the changes aren't just self contained to ert_scm.c. I'm going to try to make it an ESPHome external component for now, but would love to make a PR for this project too with your help if you're interested

Mine is actually outperforming rtl_433 with an actual USB RTL-SDR

[NorthernMan54]

Am definitely interested.

If you’re using the same CC1101 settings, then I wonder if the other difference is start and end of signal detection. If you watch the raw decodes, then you may be able to see if this is the issue and adjust it.

I presume the raw signal decode is likely good, but missing or adding bits at the start and/or end.

[Xieo]

I wrote a standalone PlatformIO program to decode SCM on my ESP32 with the 915 MHz CC1101, and it works great now. I tried to apply it to this project, but it requires changing some of the common settings this project uses (RSSI delta, bandwidth, kbps), and when I did that, I started getting real SCM decodes even with this project.

Unfortunately, it doesn't decode as efficiently as my program (~5 decodes per hour, as opposed to my ~32 decodes per hour) and the changes aren't just self contained to ert_scm.c. I'm going to try to make it an ESPHome external component for now, but would love to make a PR for this project too with your help if you're interested

Mine is actually outperforming rtl_433 with an actual USB RTL-SDR

Hi @melyux , can you share your code... I've been going into circles with the ESP32+CC1101 Module from rabbit labs I'm trying to decode SCM and SCM Plus with no success. I'm seeing raw bits but it deson't see the full stream to get a fully decoded signal.
here is one of my trials:
#203

[Ecco]

Hi @melyux ! I have also been trying to achieve something similar, and seeing that you did is really reassuring. I would also really liked it if you could share the code / build settings that you used! It really does not need to be clean / production ready.

Thanks a lot in advance!