periodic rt-tasks 
Author Message
 periodic rt-tasks

Hello NG!

We are evaluating a few rt operating systems among them also WinCE .NET.
I would like to know how I could generate pertiodic real time tasks
(jitter < 50us, call every 20ms). Are therefor special functions in the
API? I searched the MSDN several times with no luck.
Hope somebody can help me.

Alex



Mon, 07 Feb 2005 17:23:28 GMT  
 periodic rt-tasks
While(SomethingToDo)
{
   DoSomething();
   Sleep(20);

Quote:
}

This code in an appropriately high priority thread on hardware that
can handle the data rates you are after might work.
However, it's more appropriate to use an actual interrupt to reduce
Jitter. The simplest approach is to trigger the OS schedule timer at a
rate that is higher then the 1ms required by the OS. Take a look at
how the OAL implements the profiling and ILTIMING interrupts as an
example of that.

--
Steve Maillet (eMVP - Windows CE)
Entelechy Consulting
smaillet_EntelechyConsulting_Com



Quote:
> Hello NG!

> We are evaluating a few rt operating systems among them also WinCE
.NET.
> I would like to know how I could generate pertiodic real time tasks
> (jitter < 50us, call every 20ms). Are therefor special functions in
the
> API? I searched the MSDN several times with no luck.
> Hope somebody can help me.

> Alex



Mon, 07 Feb 2005 20:45:09 GMT  
 periodic rt-tasks
Thanks for the input Steve! I'm already working with the SYSINTR_TIMING
interrupt that is used by the iltiming.exe. I just wondered whether
there are some API functions that help me doing that kind of work.
As you already mentioned in your posting I can't use the sleep function
due to the poor (in my case) jitter of it.



Quote:
> While(SomethingToDo)
> {
>    DoSomething();
>    Sleep(20);
> }

> This code in an appropriately high priority thread on hardware that
> can handle the data rates you are after might work.
> However, it's more appropriate to use an actual interrupt to reduce
> Jitter. The simplest approach is to trigger the OS schedule timer at a
> rate that is higher then the 1ms required by the OS. Take a look at
> how the OAL implements the profiling and ILTIMING interrupts as an
> example of that.

> --
> Steve Maillet (eMVP - Windows CE)
> Entelechy Consulting
> smaillet_EntelechyConsulting_Com



> > Hello NG!

> > We are evaluating a few rt operating systems among them also WinCE
> .NET.
> > I would like to know how I could generate pertiodic real time tasks
> > (jitter < 50us, call every 20ms). Are therefor special functions in
> the
> > API? I searched the MSDN several times with no luck.
> > Hope somebody can help me.

> > Alex



Mon, 07 Feb 2005 22:42:53 GMT  
 
 [ 3 post ] 

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