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BS2 handle interrupt ? — Parallax Forums

BS2 handle interrupt ?

ArchiverArchiver Posts: 46,084
edited 2000-07-07 14:42 in General Discussion
I am wandering how BS2 handle external interrupt ? poll ing ?

Thank u for your help

Baker

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-07-07 05:15
    At 12:53 PM 7/6/00 +0800, you wrote:
    >I am wandering how BS2 handle external interrupt ?


    They don't - sorry.

    > poll ing ?


    That works, but make sure you don't overrun the input frequency/time frame.


    >Thank u for your help

    You're welcome


    >Baker


    Regards,

    Bruce Bates
  • ArchiverArchiver Posts: 46,084
    edited 2000-07-07 11:03
    In a message dated 7/7/00 12:15:50 AM Central Daylight Time,
    baker_bai@c... writes:

    > I am wandering how BS2 handle external interrupt ? polling ?

    Yes, you must use polling and if your interrupt event is short, you should
    probably use a one-shot to stretch it out so that the polling cycle has an
    opportunity to pick it up.
  • ArchiverArchiver Posts: 46,084
    edited 2000-07-07 14:42
    As Jon pointed out, you usually poll for external events. However, I have
    heard of some people using an external event to reset the Stamp. They also
    have the external event present on an input pin. So your code might look
    something like this:


    if in1=0 then handle_interrupt
    main:
    ' do normal stuff

    end

    handle_interrupt:
    ' interrupt code here
    goto ret_from_interrupt

    There are a few problems with this:

    1) You have to know the interrupt will not be active on a real reset (this
    could be done with external circuitry allowing you to keep the "interrupt"
    disabled.

    2) The pulse must be long enough to trigger a reset and stay low long enough
    to sense (or you could use say a flip flop and a differentiator to trigger
    the reset).

    3) You have to have some place you can always return to since the reset
    leaves no trace of where you were.

    Some programs can work like this and others can't.

    Another idea is to use a PAK-VII pulse input coprocessor to count pulses
    that arrive and then poll them at your discretion. The PAK also measures the
    pulse widths, but that isn't as important in this case.

    Regards,

    Al Williams
    AWC
    *Pulse input and output with the PAK-VII and PAK-VIII coprocessors:
    http://www.al-williams.com/awce


    >
    Original Message
    > From: baker_bai@c... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=nF3-2VzPkjXJVwnqjzEzYPxpZtMVvoDpA-u_qaUr86C3kxUIbh8slFG7m6PMCkaGGa8_Tqqo-kguUpo]baker_bai@c...[/urlOn Behalf Of
    > baker_bai@c...
    > Sent: Wednesday, July 05, 2000 11:53 PM
    > To: basicstamps@egroups.com
    > Subject: [noparse][[/noparse]basicstamps] BS2 handle interrupt ?
    >
    >
    > I am wandering how BS2 handle external interrupt ? poll ing ?
    >
    > Thank u for your help
    >
    > Baker
    >
    >
    >
    >
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