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RTOS/CC1310: Wireshark sniffer interpretation of BAD FCS

Slev1n
Genius 5680 points
Part Number: CC1310

Tool/software: TI-RTOS

Hey guys,

not sure if this is the correct sub-forum to post. I use sensor collector example with CC1310 sensors and launchpads. The sniffer is also a CC1310 launchpad. Increasing the distance between sensor node and causes the sniffer messages to contain a lot of BAD FCS and sometimes [BADFORMED PACKAGE].

The RSSI value of the uppermost message was -77dbm and was not acknowledged by the collector which was lying next to the sniffer.

1. What exactly does BAD FCS tell me? Is this a CRC issue?

2. Sometimes the collector acknowledges such messages. Can the collector make any use of the message and its content or is it discarding the message, if this frame check fails?

kind regards

Slev1n

  • 0
    TI__Mastermind 33940 points

    Hi,

    At what distance do you begin to see this issue?
    Is the environment noisy on that channel?
    If you place the sniffer close to the sensor, do you see the same "BAD FCS" frames?

    Can you share the sniffer log?

    1.
    Bad FCS indicates that the transmitted message may have been corrupted by the time it reaches the receiver.

    2.
    What kind of messages are you sending from the sensor? If this is a report message, the collector example by default will print the value on the serial console (see Csf_deviceSensorDataUpdate in csf.c).
    As detailed in the "Reception and Rejection" section of the 15.4 spec, frames with an incorrect value in the FCS field shall be discarded. So the ACKs you see likely indicate that the receiver (collector) does receive the FCS field correctly at least some of the time.

    Regards,
    Toby

  • 0 in reply to Toby
    Genius 5680 points

    Your answers regarding question 1 and 2 are very useful.

    If I go closer to the sensor without any thick obstacles I do not have the BAD FCS issues, I just wanted to know what exactly happens if the  collector receives a corrupted message. Thank you very much.