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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><link rel="STYLESHEET" type="text/css" href="wrs.css"><title> Data Collection </title></head><body bgcolor="FFFFFF"><p class="navbar" align="right"><a href="index.html"><img border="0" alt="[Contents]" src="icons/contents.gif"></a><a href="c-datacol.html"><img border="0" alt="[Index]" src="icons/index.gif"></a><a href="c-datacol.html"><img border="0" alt="[Top]" src="icons/top.gif"></a><a href="c-datacol5.html"><img border="0" alt="[Prev]" src="icons/prev.gif"></a><a href="c-datacol7.html"><img border="0" alt="[Next]" src="icons/next.gif"></a></p><font face="Helvetica, sans-serif" class="sans"><h3 class="H2"><i><a name="88260">7.6 Timestamping</a></i></h3></font><font face="Helvetica, sans-serif" class="sans"><h4 class="H4"><i><a name="88261">High-Resolution Timestamp Driver</a></i></h4></font><dl class="margin"><dl class="margin"><dd><p class="Body"><a name="84975"> </a>When you develop your application for a target with a supported timestamp driver, the instrumented kernel tags certain events with a high-resolution <i class="term">timestamp</i>. Those events are then displayed in the WindView view graph along a timeline that shows when each event occurred, based on these timestamps. You can see the exact timestamp for any particular event--for example, in the status bar, when you click on the corresponding event icon. For more details, see <a href="c-start3.html#93020"><i class="title">2.3.2 The View Graph</i></a>. <div class="frame"><h4 class="EntityTitle"><a name="84981"><font face="Helvetica, sans-serif" size="-1" class="sans">Figure 7-5: High-Resolution Timestamp Display</font></a></h4><dl class="margin"><div class="Anchor"><a name="84990"> </a><img class="figure" border="0" src="images/c-datacol20.gif"></div></dl></div></p><dd><p class="Body"><a name="84991"> </a>The timestamp driver's resolution is hardware dependent, but is typically between 100 KHz (10 microseconds per tick) and 1 MHz (1 microsecond per tick). For information on the system timestamp driver for any supported board, see <i class="textVariable">installDir</i><b class="file">/target/config/</b><i class="textVariable">bspname</i><b class="file">/target.nr</b>.<sup><a href="#foot"><b class="FootnoteMarker">1</b></a></sup> In addition to the WRS-supplied system timestamp, users may write their own timestamp driver (see <a href="x-timestamp.html#85403"><i class="title">G. Creating a VxWorks Timestamp Driver</i></a>) or use the timestamp provided by an emulator.</p></dl></dl><font face="Helvetica, sans-serif" class="sans"><h4 class="H4"><i><a name="84999">Sequence-Stamp Driver</a></i></h4></font><dl class="margin"><dl class="margin"><dd><p class="Body"><a name="85001"> </a>When the real-time system runs on an unsupported board, or on a supported board without the timestamp driver included, the instrumented kernel automatically uses its <i class="term">sequence-stamp driver</i>. This driver tags events with sequence numbers that represent the order in which the events occur on the target. The events are then spaced equidistantly from each other in the view graph; see <a href="c-datacol6.html#85012">Figure 7-6</a>. In this figure, notice the following differences from the same event log created with the timestamp driver enabled, shown in <a href="c-datacol6.html#85012">Figure 7-6</a>:</p></dl><dl class="margin"><p class="listspace"><ul class="Bullet" type="disc"><li><a name="85008"> </a>The timeline scale is in event sequence numbers rather than seconds.</li></ul></p><p class="listspace"><ul class="Bullet" type="disc"><li><a name="85019"> </a>The events are displayed equidistantly from each other.<div class="frame"><h4 class="EntityTitle"><a name="85012"><font face="Helvetica, sans-serif" size="-1" class="sans">Figure 7-6: Sequential Event Display</font></a></h4><dl class="margin"><div class="Anchor"><a name="85017"> </a><img class="figure" border="0" src="images/c-datacol21.gif"></div></dl></div> </li></ul></p></dl></dl><a name="foot"><hr></a><p class="FootnoteNumberMarker">1: <span class="Footnote"><a name="84994"> </a>For information on which target boards have timestamp drivers supported by WRS in this release, see the <i class="title">WindView Release Notes</i>.</span><p class="navbar" align="right"><a href="index.html"><img border="0" alt="[Contents]" src="icons/contents.gif"></a><a href="c-datacol.html"><img border="0" alt="[Index]" src="icons/index.gif"></a><a href="c-datacol.html"><img border="0" alt="[Top]" src="icons/top.gif"></a><a href="c-datacol5.html"><img border="0" alt="[Prev]" src="icons/prev.gif"></a><a href="c-datacol7.html"><img border="0" alt="[Next]" src="icons/next.gif"></a></p></body></html><!---by WRS Documentation (), Wind River Systems, Inc. conversion tool: Quadralay WebWorks Publisher 4.0.11 template: CSS Template, Jan 1998 - Jefro --->⌨️ 快捷键说明
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