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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Yes, you can only ask RTEMS to wait (task
wait, wait for semaphore, message queue, etc) for an integer number of clock
ticks. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>You should define the number of
microseconds per tick as the greatest common divisor (GCD) of all the time
intervals you need. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Example:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Task wake after for 10 000 us and
semaphore wait for a maximum of 12 000 us => the GCD of these numbers is 2000
us. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Therefore a clock tick should be 2000 us
and the task should wake after 5 clock ticks and the semaphore for 6 clock
ticks.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Kind regards<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Manuel Coutinho<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> rtems-users-bounces@rtems.org
[mailto:rtems-users-bounces@rtems.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Aitor.Viana.Sanchez@esa.int<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, March 27, 2009 8:22
AM<br>
<b><span style='font-weight:bold'>To:</span></b> Leonard Bise<br>
<b><span style='font-weight:bold'>Cc:</span></b> rtems-users@rtems.com;
rtems-users-bounces@rtems.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: Microseconds per tick</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
</span></font><font size=2 face=sans-serif><span style='font-size:10.0pt;
font-family:sans-serif'>Hi,</span></font> <br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>somebody
will correct me if i am wrong.</span></font> <br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>RTEMS
time functionality operates with clock_tics granularity, for instance that a
task can only sleep for a integer number of clock ticks. </span></font><br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>e.g.</span></font>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>#define
CONFIGURE_MICROSECONDS_PER_TICK 20000 /* 20 ms per clock tick */</span></font> <br>
<br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>Best
regards,</span></font> <br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>Aitor</span></font>
<br>
<br>
<tt><font size=2 face="Courier New"><span style='font-size:10.0pt'>rtems-users-bounces@rtems.org
wrote on 03/27/2009 09:11:56 AM:</span></font></tt><font size=2
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New"'><br>
<br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> Hi all,</font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> I'm quite new to RTEMS and I'm not very
experienced so I hope you </font></tt><br>
<tt><font face="Courier New">> can give me an hand!</font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> We are working with a board using a LEON2
Sparc processor running at</font></tt><br>
<tt><font face="Courier New">> 80Mhz, I figured that the microseconds per
tick value would be 0.</font></tt><br>
<tt><font face="Courier New">> 0125 (is this correct?).</font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> Shall I simply configure my application with
this define ? #define </font></tt><br>
<tt><font face="Courier New">> CONFIGURE_MICROSECONDS_PER_TICK 0.0125 ?</font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> I hope you can help, thanks in advance.</font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> Léonard. </font></tt><br>
<tt><font face="Courier New">> </font></tt><br>
<tt><font face="Courier New">> ps: By the way I posted once using the wrong
mail address and it </font></tt><br>
<tt><font face="Courier New">> said it was awaiting approval from the
moderators, please delete </font></tt><br>
<tt><font face="Courier New">> this one. This is the correct address.</font></tt><br>
<tt><font face="Courier New">>
_______________________________________________</font></tt><br>
<tt><font face="Courier New">> rtems-users mailing list</font></tt><br>
<tt><font face="Courier New">> rtems-users@rtems.com</font></tt><br>
<tt><font face="Courier New">>
http://rtems.rtems.org/mailman/listinfo/rtems-users</font></tt></span></font><o:p></o:p></p>
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