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jopohl / urh

Universal Radio Hacker: Investigate Wireless Protocols Like A Boss
GNU General Public License v3.0
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cc1101 data de-whitening Polynom wrong #254

Closed SpaceTeddy closed 7 years ago

SpaceTeddy commented 7 years ago

cc1101 de-whitening Plynom is pre set to 0x21 that means x^5+x^0. regarding to datasheet or app note: http://www.ti.com/lit/an/swra322/swra322.pdf , Polynom should be x^9+x^5+x^0 -> 0x221

andynoack commented 7 years ago

Well, in this case the degree of the polynomial is ignored. Does it work for you using 0x21?

SpaceTeddy commented 7 years ago

I can not fully understand the feedback of urh. If I send data out with 100kbit GFSK I can interprete the sniffed data till the the sync word. i.E. snyc word 0x57 ox43; package len = 6; destination address = 03; tx_address = 01 aaaaaaaa 57435743 08083c000c30301070400040a3746d12480b7cc1
|preamble| sync | payload

preamble and sync word is correct. Playload is strange. I disabled already FEC and payload whitening, but I can still not find the correct data. After that, I will check the whitening decoding again chris

andynoack commented 7 years ago

Ah ok, then I reopen the issue and we will see. Can you upload the signal you sniffed and tell where the error in the decoding is?

SpaceTeddy commented 7 years ago

Implementation of CC1101 de-whiteing with Lfsr=0x21 is correct. TX payload: aaaaaaaa 57435743 f9e21c9aec8730feef decoded: aaaaaaaa 57435743 06030100010203da05

andynoack commented 7 years ago

Great, nice to hear that :)