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11<H1 align="left">OS_InitTick <IMG src="../../image/NTR.gif" align="middle"><IMG src="../../image/TWL.gif" align="middle"></H1>
12<H2>Syntax</H2>
13<DL>
14  <DD>
15  <PRE><CODE>#include &lt;nitro/os.h&gt;</CODE></PRE>
16  <PRE><CODE>void OS_InitTick( void );
17 </CODE></PRE>
18</DL>
19<H2>Arguments</H2>
20<P>None.</P>
21<H2>Return Values</H2>
22<P>None.</P>
23<H2>Description</H2>
24<P>This function allocates a timer for ticks and initializes it.</P>
25<P><EM>Ticks</EM> are a method of using a hardware timer to generate a <CODE>u64</CODE> increment count. A tick is also the obtained value. Although the timer itself is 16 bits, in addition to the 16-bit cycle, which is one unit, there is also an internal counter.  As a result it creates a 64-bit tick value. (The frequency of the system clock is <CODE>OS_SYSTEM_CLOCK</CODE> Hz, so ticks run at <CODE>OS_SYSTEM_CLOCK</CODE> / 64 Hz.)</P>
26<P>The <CODE>OS_InitTick</CODE> function internally sets the tick value to 0. Therefore it is possible to assume that the value obtained with the <CODE><A href="OS_GetTick.html">OS_GetTick</A></CODE> function is the time since <CODE>OS_InitTick()</CODE>.</P>
27<P>A timer that is allocated for ticks becomes system-reserved. A user cannot use it as a timer with the <CODE><A href="../timer/OS_StartTimer.html">OS_StartTimer</A></CODE> function or similar functions. Do not call the <CODE>OS_InitTick</CODE> function if the user wants to use all of the timers.</P>
28<P>Ticks are necessary when you use the alarm system. Call <CODE>OS_InitTick()</CODE> before calling the alarm system initialization declaration function <CODE><A href="../alarm/OS_InitAlarm.html">OS_InitAlarm</A></CODE>.</P>
29<H2>See Also</H2>
30<P><CODE><A href="OS_GetTick.html">OS_GetTick</A>, <A href="OS_GetTickLo.html">OS_GetTickLo</A>, <A href="OS_SetTick.html">OS_SetTick</A>, <A href="../alarm/OS_InitAlarm.html">OS_InitAlarm</A><BR></CODE></P>
31<H2>Revision History</H2>
32<P>2004/02/25 Changed <code>systemClock</code> to <code>tick</code>.<br /> 2004/02/04 Initial version.</P>
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