433mhz weather station not seen by HA

TheHoff · May 31, 2021, 5:59am

Hi all
I recently bought a Clas Ohlson (Cotech) weather station, rain/wind/temp, that uses 433mhz as radio. I’ve got a RFXcom 433XL set up controlling some other devices and sensors but I haven’t got the weather station working. I did a test with the 433XL connected to my PC with RFXmngr and nothing was seen even with all options enabled and the latest firmware, when I enabled “unknown” some strings passed by but was unreadable.
I guess the case is I have to wait for RFXcom to release a firmware with support for the cotech weather station?

Regards
Fredrik

FredTheFrog · May 31, 2021, 12:32pm

Is it Model # WH-1080? If so, that is a clone of the Fine Offset device.

TheHoff · June 2, 2021, 5:46am

No, it seems to be a newer one. FT0203 I think it’s the model

FredTheFrog · June 8, 2021, 10:45pm

Aha. A SainLogic product, I see.

The Sonoff RFBridge running Tasmota will dump raw packets from their 433 MHz weather station. But capturing those packets and decoding them as sensors into Home Assistant is a significant bit of development effort. See this web page for an example and Github page of someone who did a very complete job researching and decoding their 433 MHz data and doing it with an ESP8266.

I’m trying (and not entirely succeeding) at converting Axlan’s 8266 firmware to ESPHome, specifically to get Home Assistant compatibility. I just got started a week ago, and don’t have it running yet. It will probably be a few more weeks before I get something barely workable.

Wish I could give you better news.

1technophile · June 12, 2021, 10:07pm

Hi,

You can take a look to RTL_433 is seems to support Cotech

github.com

merbanan/rtl_433/blob/7480c9c9f986859fdf0f661562f05509cc30a383/src/devices/cotech_36_7959.c

/** @file
    Cotech 36-7959 Weatherstation.

    Copyright (C) 2020 Andreas Holmberg <[email protected]>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
*/

/**
Cotech 36-7959 Weatherstation, 433Mhz.

OOK modulated with Manchester encoding, halfbit-width 500 us.
Message length is 112 bit, every second time it will transmit two identical messages, packet gap 5400 us.
Example raw message: {112}c6880000e80000846d20fffbfb39

Integrity check is done using CRC8 using poly=0x31  init=0xc0

This file has been truncated. show original

Check that your model fits maybe.

You would need an RTL_SDR device but it is an interesting investment to explore RF.