Panasonic CS-Z20TKEW CRC issue

[ultraschall81]

Hi,
I have used and adopted the code from https://www.analysir.com/blog/2014/12/2 ... -protocol/
and a tool (Arduino) to decode the actual remote control signals.
I do not flip the bits, thats why my hex values starts with 0x40040720. In the send function, I send the bytes inverted. When I use a recorded string, the AC is reacting with a "beep" to my program. But I have probems calculating the CRC.
The article says: "The checksum is the sum (addition) of the previous 18 bytes modulo 256 (frame 2 only)."
But if I do this I get a slightly different CRC byte.
For example: (second frame only)
HVAC_HOT, 27, FAN_SPEED_5, VANNE_V3,Wide_Auto, NORMAL, true: 0x 40,4,7,20,0,92,6C,1,CE,B0,0,70,7,0,0,91,0,0 gives a CRC of 0F but the remote control has CRC of 3F. All other bits are identical.
Same for HVAC_HOT, 25, FAN_SPEED_5, VANNE_V3,Wide_Auto, NORMAL, true:
My Programm has CRC of 2F and the remote control has 1F.

So the first part of the CRC byte differs by one or two.

Has anyone a hint, how to calculate the CRCin new Panasonic ACs?

Thanks for your help.

Christian

[AnalysIR]

If you have a copy of AnalysIR, you can use the checksum calculator & reverse engineering tool to assist.

If not, post a set of raw signals & I will have a quick look (but may take a few days to respond).

[ultraschall81]

Hi,

I don't have AnalyseIR.
It would be great, if you can help me. Attached is a log of the remote control.

Thanks for your help.

Br

Christian

[AnalysIR]

Sorry

That is the wrong format...I need the RAW timings

like

9000,4500,560,560,560,1680,560....etc

[ultraschall81]

No Problem,

file is attached.

[AnalysIR]

Your signal decodes fine in AnalysIR.

2019-01-08 15_23_22-AnalysIR 1.16.100.8303.jpg

However, it is sent in 2 parts and thus has 2 independent checksums.

The checksum is calculated as the sum of all bytes except the last byte. The last byte is the actual checksum.

The same calculation is made for each part of the signal.

PS: I also had to use the LSB8 format within AnalysIR, which reverses the bit order within each byte.

.....have fun

[ultraschall81]

Hi,

thanks for your analyse and sorry for the late response.
I think, I got a hint, where my error could be. I have to refactor my code (correct ‘bit order’).

Br

Christian

[AnalysIR]

Thanks for the update. yes indeed....its a lot easier with tools like AnalysIR