Subject:
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Re: Time available during 1 kHz system interrupt?
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 2 Nov 1999 12:47:39 GMT
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Original-From:
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Bruce Moore <bamoore@bloomington.NOMORESPAMin.us>
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Viewed:
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579 times
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Interesting discussion but it raises a few more questions.
Are there any (bad) side effects when user code that is inserted in the ISR
takes longer to execute than the 1 msec interrupt cycle. From experience
it appears that the ISR runs on the next interrupt following the completion
of the current cycle. The only thing I noticed is that the PWM routines
don't always calculate their next transition correctly but i figure that
there are plenty of other things that are going on that I'm not watching
(and that may eventually bite me).
Chris: How do you turn off the things like IR and quad shaft decoding to
get rid of the little overhead.
----------
> From: Christopher Prosser <cprosser@acm.org>
> To: Greg Starr <starr@unm.edu>; handyboard@media.mit.edu
> Subject: Re: Time available during 1 kHz system interrupt?
> Date: Monday, November 01, 1999 8:48 PM
>
> Hi Greg,
> It all depends. Various features of the HB can be turned on and off to
> change the amount of work done in the main ISR. By default the code uses
> 300ms to execute. The file lib_hb.c provides the following:
>
> /********************************/
> /*** System Interrupt Control ***/
> /********************************/
>
> /*
>
> These functions allow you to turn on and off various features
> controlled by the system interrupt routines. The more features
> you turn off, the faster your code will run.
>
> On reset, the features have the following state:
> pulse width modulation ON
> infrared decoding ON
> LCD printing ON
> quad shaft decoding OFF
> IR tranmission OFF
>
> This uses approx. 30% of total CPU time.
>
> Approximate benchmarks:
>
> x Feature % of CPU
> ------- --------
> PWM 3
> IR decode 11
> LCD printing (active) 8
> LCD printing (inactive) 1
> quad shaft decode 5
> IR transmission 1
>
> */
>
>
>
> -chris prosser
>
>
> ----- Original Message -----
> From: Greg Starr <starr@unm.edu>
> To: <handyboard@media.mit.edu>
> Sent: Monday, November 01, 1999 7:19 AM
> Subject: Time available during 1 kHz system interrupt?
>
>
> > Does anyone know the approximate amount of time available for user
> > assembler programs which "add on" to the existing 1 kHz HB interrupt?
> >
> > Another way of stating that is...how much time is used by the 1kHz HB • ISR
> code?
> >
> > --greg
> >
> > *****************************************************************
> > * Greg Starr, Professor *
> > * Department of Mechanical Engineering ph (505) 277-6298 *
> > * University of New Mexico, Albuquerque NM 87131 FAX 277-1571 *
> > * email- starr@unm.edu WWW- http://www.me.unm.edu/~starr/ *
> > *****************************************************************
> >
> >
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