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CRC calculation in packet sniffer

ami
Prodigy 100 points
Other Parts Discussed in Thread: CC2510, CC2511, CC-DEBUGGER

Hi all,

This might be a trivial issue, but i don't know what exactly am I missing. 

I noticed while using the Packet sniffer in generic mode that even when sending the same packet the CRC value is changing .. according to the CC2510/11 datasheet the CRC is calculated over the whole payload, which in my case is not changing (I'm not using sequence numbers). so I can't find out why the CRC is still changing. 

Any clues why this is happening?

I'm using CC2511 as sniffer, and CC2510 with SmartRF studio as TX

example output of the sniffer can be found below. 

+----------------------------------------------------+----------------- - - -
| Packet sniffer frame header |
+----+-------------+-------------------------+-------+
|info| Packet nbr. | Time stamp | Length| Packet data
+----+-------------+-------------------------+-------+----------------- - - -
| 11 | 54 00 00 00 | 65 03 32 99 25 00 00 00 | 07 00 | 04 03 41 42 43 4A A3
+----+-------------+-------------------------+-------+----------------- - - -

+----------------------------------------------------+----------------- - - -

| Packet sniffer frame header |
+----+-------------+-------------------------+-------+
|info| Packet nbr. | Time stamp | Length| Packet data
+----+-------------+-------------------------+-------+----------------- - - -
| 11 | 56 00 00 00 | 16 91 A3 99 25 00 00 00 | 07 00 | 04 03 41 42 43 4A 8E
+----+-------------+-------------------------+-------+----------------- - - -

+----------------------------------------------------+----------------- - - -
| Packet sniffer frame header |
+----+-------------+-------------------------+-------+
|info| Packet nbr. | Time stamp | Length| Packet data
+----+-------------+-------------------------+-------+----------------- - - -
| 11 | 55 00 00 00 | 59 CA 6A 99 25 00 00 00 | 07 00 | 04 03 41 42 43 4A A1
+----+-------------+-------------------------+-------+----------------- - - -

  • 0
    Prodigy 100 points

    Ok so it seems I was misinterpreting the packet. The last 2 bytes are not the CRC, but the packet status info (RSSI & LQI). 

    Is there a way to read the calculated CRC value by the receiver, since it can't be viewed from the packet sniffer as far as i've seen ??

  • 0 in reply to ami
    TI__Guru 56590 points

    Hello,

    If you have a CC-Debugger or a SmartRF05EB you can use SmartRFStudio instead and configure exactly what you want.

  • 0 in reply to Eirik V
    Prodigy 100 points

    Hi Eirik V,

    Thanks for your suggestions.

    I am already using SmartRF Studio with SmartRF04EB .. I have tried to configure the registers (PKTCTRL1) such that RSSI & LQI bytes are disabled, however, they still continue to appear in the packet sniffer.

    Also, I don't seem to find what is the CRC value calculated using SmartRF studio. Is it possible to view it at all ?