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Topic: Please help me decode 433Mhz temperature sensor HYUNDAI WSC 1925 (Read 4965 times) previous topic - next topic


what IDE are you using guys? Arduino IDE seems to be not so good, notepad++ works better (have suggestions; function list; multiwindows etc).
Notepad++ for me every time.  :)
Don't PM me for help as I will ignore it.


Guys, maybe I can help little bit. I have spent some time hacking Hyundai WS 1815 which I believe use the same protocol. And I used your published tools here to make a working sensor emulator.

First, let me clarify the protocol, although you got most of it already:

  • first 4 bits are checksum ( sum nibbles - 1 modulo 16)
  • next 8 bits is station ID - it's generated randomly in sensor after power on. Does not seem to matter what that is
  • next 12 bits is the temperature in Celsius. Positive values and negative values are encoded in 12 bits. There is no freezing bits or whatever.
     +10 is 000001100100b and -10 is 111110011011b. It's binary complements.
  • next 2 bits is channel (1-3)
  • next bit is battery status 0-low, 1-OK
  • last bit is force sync (it's set when you power on sensor for the first time or press TX button on it). It just makes the base station beep.

The signal is repeated several times. 6 times works reliably for me.

I'm attaching working Arduino sketch which encode the payload to binary form and trasmit it.



yes, that use exactly the same protocol. You can use this https://github.com/joysfera/arduino-water-temp-transmitter directly to form and send packet.


Hi pedobry,
I will look on your sketch, maybe there is something new.

The protocol was successfully cracked before (and man can say, first, from left, 4 bits from temperature are freezing bits - 1111 - and then use two complement or normal temperature 0000). Last problem was to write functional sketch/libraries (transmitting, receiving).

From now I have testing these sketches and seems, that my 433Mhz hardware is bad. I'm not able to get temperature from outer station. I have special glass in windows (anti thief). Original meteo station have no problems... I have buy new modules. Today I will test opened windows and longer antennas.



Hi guys,
actually I'm very busy and don't have time to play with Arduino :/

I'm looking for some good IDE (I need to try them all; very good looks sublime text - but it's not free... need to test all IDE's that I find).

And I have continuously searching for good meteo station. I have find very good on Conrad with solar panel:

But after some time, I have discovered, that all of this types are only china overpriced products.
and Hyundai has this meteo station too (with nice caption Hyundai :)).

OK, then I have find this article

and have googled to find this on Czech Republic... whoala:
and on black friday price was +-1200Kč (+-50$) - unbeatable price for this set (receiver!, transmiter with temp and humi!). Probably on aliexpress will be this product too.

So first target is to get my old Hyundai to work (still have bad 433MHz receivers; delivery of good ones will be at January probably). I have find, that code posted on post #29 doesn't use two complement (bug).

Then hacking of new china meteo station.

I have buy one solar panel too (12V, 30W) and have one old little from garden light (looks identical that use Conrad on solar meteo; probably china generic for everybody and everyday use)

With best regards

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