Xiaohui:

Please find my answers below.

Are you aware of any case other than failing address recognition that will
> cause CC2420 to discard a frame? If not, problem (2) (see 
> here<http://electronics.stackexchange.com/questions/50335/how-to-timestamp-packets-with-cc2420-and-msp430f1611>)
> seems gone if address recognition is disabled. What about problem (1)? How
> is it handled in CC2420X?
>
If there are two consecutive SFD interrupts, and the first one is missed,
the FIFO won't be empty after reading out a packet (since there's another
packet in there). The SFD timestamp will correspond to the second packet.
Currenlty, the cc2420x handles this by dropping both packets. This is a
pretty safe solution. Alternatively, the packets could be accepted, with
the timestamp_isValid fields set to FALSE -- there are some comments in the
code explaining this.



> Is is necessary for SPI to be faster than packet reception for CC2420X's
>> timestamping mechanism to work correctly? Or it is just of performance
>> concern?
>>
> No, it's not necessary. It's purely for performance reasons.

Janos
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