[Tinyos-2-commits] CVS: tinyos-2.x/doc/html tep113.html,1.10,1.11

[Phil Levis]

Update of /cvsroot/tinyos/tinyos-2.x/doc/html
In directory sc8-pr-cvs10.sourceforge.net:/tmp/cvs-serv29464/html

Modified Files:
	tep113.html 
Log Message:
David Gay's edits.


Index: tep113.html
===================================================================
RCS file: /cvsroot/tinyos/tinyos-2.x/doc/html/tep113.html,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -d -r1.10 -r1.11
*** tep113.html	14 Aug 2007 18:57:59 -0000	1.10
--- tep113.html	1 Apr 2008 17:01:30 -0000	1.11
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*** 299,305 ****
  <tr class="field"><th class="docinfo-name">Draft-Created:</th><td class="field-body">11-Jul-2005</td>
  </tr>
! <tr class="field"><th class="docinfo-name">Draft-Version:</th><td class="field-body">1.9</td>
  </tr>
! <tr class="field"><th class="docinfo-name">Draft-Modified:</th><td class="field-body">2007-02-06</td>
  </tr>
  <tr class="field"><th class="docinfo-name">Draft-Discuss:</th><td class="field-body">TinyOS Developer List &lt;tinyos-devel at mail.millennium.berkeley.edu&gt;</td>
--- 299,305 ----
  <tr class="field"><th class="docinfo-name">Draft-Created:</th><td class="field-body">11-Jul-2005</td>
  </tr>
! <tr class="field"><th class="docinfo-name">Draft-Version:</th><td class="field-body">1.11</td>
  </tr>
! <tr class="field"><th class="docinfo-name">Draft-Modified:</th><td class="field-body">2008-04-01</td>
  </tr>
  <tr class="field"><th class="docinfo-name">Draft-Discuss:</th><td class="field-body">TinyOS Developer List &lt;tinyos-devel at mail.millennium.berkeley.edu&gt;</td>
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*** 530,533 ****
--- 530,550 ----
  be transmitted may begin spooling into SerialP while SerialP is
  actively sending an acknowledgement.</p>
+ <p>Only the PC-to-mote communication path supports acknowledgements.
+ SerialP does not request acknowledgements from the PC for two reasons.
+ First, acks are not perfect reliable: they are used on the
+ PC-to-mote path to raise reliability to a usable level. In the case of
+ the PC-to-mote path, the UART receive buffer is typically a single
+ byte, so a high interrupt load can easily lose (and sometimes does) a
+ byte. This is in contrast to the PC receive buffer, which is much
+ larger and does not have to deal with overflow. Second, adding support
+ for acks would increase the code size and complexity of the serial
+ stack. As code space is often at a premium, this would add little
+ needed functionality at significant cost. Of course, any application
+ that requires perfect reliability may layer its own scheme on top of
+ the serial protocol.</p>
+ <p>The acknowledgement protocol is stop-and-wait to minimize buffering on
+ the mote side. This is considered more important on memory constrained
+ devices than increased throughput in the PC-to-mote direction, which
+ most applications only use for occasional control transmissions.</p>
  </div>
  <div class="section">