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Panasonic AC ir CRC
Posted: Wed Sep 16, 2015 1:45 am
by devd
when i Decode Panasonic protocols first frame is 4004072000000060 last one is CRC = 60 hex
but when modulo 256 sum then ans = 6B hex and its happen in frame two also
how to decode it ? and consider 6B as 60
Re: Panasonic AC ir CRC
Posted: Fri Sep 18, 2015 1:39 pm
by AnalysIR
The checksum is the last byte in each part of the IR signal and is calculated by the SUM of all the preceding bytes in that part.(do not include the last byte in the calculation)
There is a very good explanation of reverse engineering the Panasonic Air Conditioner (Aircon) Infrared signals here, including checksum.
http://www.analysir.com/blog/tag/panasonic/
The 'trick' is that you must reverse the order of bits for each byte first. (we call this LSB8).
AnalysIR has in-built tools that makes all of this easy.
- Decoding to Hex/Binary
- Change bit order from MSB to LSB to LSB 8
- Checksum calculator
- Reverse Engineering tool
- and lots lots more....