Subject:
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Re: Reading sensors at equal intervals.
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 26 Apr 1999 18:39:01 GMT
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Viewed:
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1399 times
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S. Crawshaw <sc10003@eng.cam.ac.uk> wrote:
> How does the timing of tasks work? I seem to recall reading somewhere that
> the firmware executes the tasks in sequence - is there any timing element
> to this, or does it just do task 1, then immediately onto task 2, etc, and
> back to task 1 when it's done. (I'm hoping that it starts each task at a
> predictable time...) Or have I got this completely wrong?!
IIRC, it preferentially executes a single instruction received from the IR
connection, otherwise takes the next instruction from the next task and
executes that instead.
> Alternatively, if leave NQC etc behind and go to "H8-land", is it possible
> to use LegOS or similar to generate a software interrupt at regular
> intervals?
Probably. I don't think LegOS supports (what I'd call) a software
interrupt at regular intervals, but it does have preemptive multitasking
that switches on 20 ms intervals, and you can make a task have such high
priority that it is guaranteed to run at the start of every 20 ms, so close
enough. And you can probably tweak the source too to change the 20 ms to
something else.
> Failing that, I'm willing to write in pure H8 assembly language if
> necessary (although I don't really want the hassle of setting up the H8
> stuff for gcc)
There is a hassle in setting up gcc (or egcs?), especially if you don't
have a Unix box, but there are instructions on the net for doing this,
and in my opinion it's well worth it once you've got over the setup hurdle.
-Kekoa
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Message is in Reply To:
 | | Re: Reading sensors at equal intervals.
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| (...) <snip> (...) That looks like a "no" then... How does the timing of tasks work? I seem to recall reading somewhere that the firmware executes the tasks in sequence - is there any timing element to this, or does it just do task 1, then (...) (25 years ago, 26-Apr-99, to lugnet.robotics)
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