Hi Bertrand,

I don't think I understand the kernel enough to modify/improve codes yet.  I just downloaded the OSEK standard, but I haven't got time to read through it.  What I can do now is to test the OS and report to you if there is anything wrong/broken.  Sounds good?

Regards,
Thomas

bertrand.rozier@PRAGMATEC.NET wrote:
Hello Thomas,

Do you prefer to contribute to an existing OS?
I suggest to you PICos18 ;-)
it is a GPL RTOS for PIC18 based on OSEK standard.
check here : www.picos18.com
For further information, you can contact me on the forum(www.picos18.com\forum)

Regards

Bertrand


Selon Thomas :

> Thanks all of you for your reply! Wow, I didn't
> expect to have so many responses in a short amount of
> time. Instead of replying to each of you in separate
> Email, I am replying to all of you in this Email.
> Please see my answer to some of your
> questions/comments:
>
> Wouter van Ooijen: do you mean that you want to run
> each task at 10 ms with great accuracy on that 10 ms
> interval? (As opposed to long-term accuracy on that
> interval)?
> Thomas: What I want to avoid is to have one task
> waiting for two or more tasks to finish.
>
> Jan-Erik: Per definition, a processor like the PIC's
> can't do more then one thing "at the same time".
> Thomas: Yes, I do understand that the PIC is not an
> Intel's HT uP! When one task is initialized few
> cycles after another, I consider it "at the same
> time". I don't think I should use this term any more
> because people always give me the same comments like
> you did. :-)
>
> Jan-Erik: Does "the last task" KNOW it have been
> delayed 3 ms ? Does "the last task" even CARE it have
> been delayed 3 ms ? If not, what's the problem ? Are
> "the last task" syncronized to some external event so
> it have to "respond" within some specific time limit
> (less then 3 ms) ?
> Thomas: The task doesn't know that it gets delayed.
> Anyways, I don't think it matter much now.
>
> Jan-Erik: Well, run it at a lower speed, so each task
> takes 2.5 ms
> Thomas: Why would you want to run a task at lower
> speed? Are so trying to fill up the idle time so that
> it appears efficient... to me?
>
> Jan-Erik: Now, if a task to be run "right away"
> (whatever *that* is )
> Thomas: OK! OK! Please don't pick on every single
> word I use in my Email because English is not my first
> language. "right away" in my term, is the OS is
> scheduling this task and only this task to run. Is
> this good enough?
>
> Bertrand: What is the OS you use?
> Thomas: I am trying to write my own.
>
> For everyone else:
> Thomas: Thank you for your effort to help me! All I
> am looking for was to see if there is any way I can
> write the OS so that it spaces out the tasks to avoid
> having too many waiting tasks at the same time.
>
> Regards,
> Thomas
> --- Colombain Nicolas
> wrote:
> > Hi Thomas,
> >
> > > Says my program has 4 tasks. Each of them
> > requires
> > > 1ms to execute and I want to run them every 10ms.
> > If
> > > the OS initializes all tasks at the same time
> > (this is
> > > usually the case), after 10ms, all 4 tasks are
> > ready
> > > to run. Regardless of how the OS determines which
> > > task to run first, the last task won't be executed
> > > until 3ms later. This is quite inefficient
> > because
> > > for the next 6ms, the system will sit idle, doing
> > > nothing.
> > >
> > > Would it be better if the OS:
> > > - starts the first task at time 0
> > > - start the second task 2ms later
> > > - start the third task 4ms later
> > > - start the fourth task 6ms later
> > It would be better sure :)
> >
> > > The above example is simple because the duration a
> > > task is known and the executing period is the
> > same.
> > > What would happen if they are all different? What
> > > would you do to avoid having two or more tasks
> > ready
> > > to run at the same time?
> >
> > - Let the user specify the max duration of each
> > task. Then compute the best
> > time schedule.....
> > or Do nothing....
> >
> > The best arrangement can only be done by the user
> > depending on each task.
> > Perhaps an RTOS with more options can be foreseen:
> > - fixed task duration + time of the task
> > - max task duration + min
> > - unknow task duration
> > - synchronous task
> > - Asynchronous task
> > With all these informations, you can try to find the
> > best time schedule.
> > Regards,
> >
> > Nicolas
> >
> > --
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> > AutoReply us!
> > email listserv@mitvma.mit.edu with SET PICList
> > DIGEST in the body
> >
>
>
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