[Tinyos-help] False acknowledgments and CRC

renjie huang huangrenjie.hust at gmail.com
Tue Mar 4 09:49:54 PST 2008


When I read following link, I have some questions:

http://docs.tinyos.net/index.php/CC2420_Known_Issues

"False acknowledgments can get sent back for corrupted packets that are not
actually received. The issue is that acknowledgements are sent before the
CRC check is performed."

Does it mean hardware acknowledgments are send before CRC check is
performed? But from CC2420 datasheet, it seems that AUTOCRC should be also
enabled when hardware acknowledgment is enabled. Following is from CC2420
data sheet:
"CC2420 includes hardware support for transmitting acknowledge frames, as
specified in [1]. Figure 22 shows the format of the acknowledge frame.

If MDMCTRL0.AUTOACK is enabled, an acknowledge frame is transmitted for all
incoming frames accepted by the address recognition with the acknowledge
request flag set and a valid CRC. AUTOACK therefore does not make sense
unless also ADR_DECODE and AUTOCRC are enabled. "


-- 

                                                          Renjie
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.millennium.berkeley.edu/pipermail/tinyos-help/attachments/20080304/8a4810d4/attachment.html


More information about the Tinyos-help mailing list