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I am trying to decode the Bresser Water Leakage sensor, the current state of work can be found in https://github.com/matthias-bs/rtl_433/blob/master/src/devices/bresser_leakage.c

I have also created an issue with some background information for integrating the decoder in the rtl_433 project.

Decoding the payload works fine, but I did not find out how the checksum is calculated. The data layout and samples are provided in bresser_leakage.c.

I have already tried the following:

  1. Digest calculations used in rtl_433 decoders for other Bresser sensors
  • with varying payload lengths)
  • with iterating the key in the range 0...0xFFFF
  1. revdgst (with varying payload lengths)

  2. reveng (with varying payload lengths) - no meaningful result at all

  3. CRC calculators on https://crccalc.com/

  4. Simple checksum algorithms like ADD, XOR, SUB

  • on bytes
  • on nibbles
  • on 16-bit chunks
  1. Parity
  • bits set - byte wise/nibble wise, first/second half of message, ...

None of these attempts were successful.

I would be happy if anyone could help.

Thank you very much in advance!

Matthias

1 Answer 1

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The checksum has been found! It's a CRC16/xmodem covering the 5 bytes following the CRC.

See https://github.com/merbanan/rtl_433/issues/2576#issuecomment-1751134478

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