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CC1352R: Unexpected RF messages

Vincenzo Cristiano
Intellectual 710 points

Part Number: CC1352R


Hi,


my project has two different kinds of nodes based on CC1352R , collector and sensor, that communicate through RF packets. In order to check the communication, I put a launchpad to sniff every data going on the radio using smartRF-Studio. Suddenly, in the receiving packets by the sniffer I have this:


11:39:08.830 | db | 48781 | b5 b9 6d 04 1d 14 ef 54 aa b316 7d f9 52 b6 9a ac 4e d6 4e ca 28 ef b6 d9 33 5b f6 c8 b5 63 76 a2 e9 ce 58 e0 d7 ef 3c 92 3d ac d8 ae 05 d4 b2 be d1 55 39 94 e6 d3 39 16 81 fb f7 a7 ea fb f7 e9 20 18 8b 51 27 4b 6a 6e 27 0e da 77 86 a2 d2 2a d0 0d 5b b7 1b 6c d6 b7 32 a8 56 29 a8 60 c4 d3 5d 16 2b 9f 28 75 92 22 48 d0 6a e7 4d 7f 3b f4 ef 6d 09 6f 4b ed 04 23 cd cf a5 ff 6e ce a9 68 98 98 55 33 7f f6 f2 4c c9 8a b4 89 41 64 ad 25 ae 8a f2 f7 df 7d 7d 10 9b 45 17 b1 56 93 37 2b 61 af f5 45 76 5a 22 ed 79 e2 ae bd d4 a9 38 82 8b 78 a0 81 a1 b5 fa db eb 7f ff 79 2e 06 d3 55 15 78 4a ae 8f e2 8c 7a 68 b3 39 6d 2f a3 50 fc 46 93 56 f5 4d 8d 4a ba  | -103 CRC error


This is an unknown message which I do not produce in my code. 

Is it possible to detect some weird noise from external sources? In this case, the RF module will detect an erroneous packet (e.g.CRC error)?

Moreover, if the sniffer read well the packet means that the preamble was good. Does it mean that the RF packet was created from one of my nodes?

best regards, 
Vincenzo

  • +1
    TI__Guru* 87971 points

    It is fully possible to detect a "sync word" in noise, and having the radio receive whatever is following. This will then result in a CRC error.

    This will not happen very often if you use a 4 byte long sync word with good auto correlation properties, but the likelihood will increase if you for example reduce the sync word length. You will see that if you set the sync word to be 8 bits and put a device in RX using SmartRF Studio, you will most likely receive several packets a minutes, just from noise.

    In your application (not in SmartRF Studio) it is possible to set RF_cmdPropRx.rxConf.bAutoFlushCrcErr = 1 to discard packets with CRC error from Rx queue.

    That means that you can have a callback on RF_EventRxEntryDone, and only check the received data when this even occur, as packets with bad CRC are automatically discarded.

    Siri

  • 0 in reply to Siri
    Intellectual 710 points

    Thank you for your reply Siri! 

    Yeah, I did the test you suggest with 1byte syncword and in few minutes there were dozen of packets from noise. 

    Unluckily, in my project we cannot flush any CRC error so I have to improve my code when that error happens. 


    Thank you, 
    Vincenzo.