Counting 2ms long pulses on several input pins

From	pozz <pozzugno@gmail.com>
Newsgroups	comp.arch.embedded
Subject	Counting 2ms long pulses on several input pins
Date	2013-09-23 23:42 +0200
Organization	A noiseless patient Spider
Message-ID	<l1qck1$9dd$4@dont-email.me> (permalink)

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I have a 5 microswitches 
(www.tamiyausa.com/images/product/470/75016/header_75016.jpg) connected 
to some inputs of a microcontroller.  The switches are normally closed 
and put the level to low.  When they are open, the level is high thanks 
to pull-up resistors.

I have to count the pulses generated from the microswitches.  They are 
managed by a rotating cam (en.wikipedia.org/wiki/Cam) that push/release 
continuously the switches.

The rotation speed could change. When it is slow, the complete pulse 
width could be up to 15-20ms, where the last part (about 3-5ms) is 
composed by many bouncing oscillations.
When the rotation is fast, the complete pulse width is about 1-2ms and 
the boucing oscillations takes about 2-3ms.

What is the best approach/algorithm to debounce and detect/count pulses 
on all the lines, without stressing the microcontroller too much?

My approach is to sample each input lines every 1ms in the ISR of a 
timr.  Usually it is at low level.  When I see the first 1, I increase 
the counter and change to HIGH status.  Now I have to see two 
consecutives 0 to go back to LOW status.

Do you have better ideas?

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Thread

Counting 2ms long pulses on several input pins pozz <pozzugno@gmail.com> - 2013-09-23 23:42 +0200
  Re: Counting 2ms long pulses on several input pins mike <ham789@netzero.net> - 2013-09-23 15:00 -0700
  Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-23 16:12 -0700
  Re: Counting 2ms long pulses on several input pins Paul Rubin <no.email@nospam.invalid> - 2013-09-23 18:45 -0700
    Re: Counting 2ms long pulses on several input pins Arlet Ottens <usenet+5@c-scape.nl> - 2013-09-24 08:06 +0200
      Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 00:37 -0700
        Re: Counting 2ms long pulses on several input pins Arlet Ottens <usenet+5@c-scape.nl> - 2013-09-24 10:24 +0200
          Re: Counting 2ms long pulses on several input pins Paul Rubin <no.email@nospam.invalid> - 2013-09-24 02:05 -0700
            Re: Counting 2ms long pulses on several input pins Arlet Ottens <usenet+5@c-scape.nl> - 2013-09-24 11:01 +0200
          Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 09:55 -0700
            Re: Counting 2ms long pulses on several input pins Tom Gardner <spamjunk@blueyonder.co.uk> - 2013-09-24 18:13 +0100
              Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 11:03 -0700
            Re: Counting 2ms long pulses on several input pins Arlet Ottens <usenet+5@c-scape.nl> - 2013-09-24 19:38 +0200
              Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 11:13 -0700
                Re: Counting 2ms long pulses on several input pins Arlet Ottens <usenet+5@c-scape.nl> - 2013-09-24 20:30 +0200
                Re: Counting 2ms long pulses on several input pins Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-09-24 21:20 +0100
                Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 16:08 -0700
    Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 00:34 -0700
  Re: Counting 2ms long pulses on several input pins Andrew Smallshaw <andrews@sdf.lonestar.org> - 2013-09-24 04:31 +0000
  Re: Counting 2ms long pulses on several input pins Paul E Bennett <Paul_E.Bennett@topmail.co.uk> - 2013-09-24 11:15 +0100
    Re: Counting 2ms long pulses on several input pins Paul <paul@pcserviceselectronics.co.uk> - 2013-09-24 15:51 +0100
  Re: Counting 2ms long pulses on several input pins pozz <pozzugno@gmail.com> - 2013-09-25 00:33 +0200
    Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 16:36 -0700
      Re: Counting 2ms long pulses on several input pins pozz <pozzugno@gmail.com> - 2013-09-25 07:39 +0200
        Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-24 23:37 -0700
          Re: Counting 2ms long pulses on several input pins pozz <pozzugno@gmail.com> - 2013-09-27 15:54 +0200
            Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-27 12:35 -0700
    Re: Counting 2ms long pulses on several input pins mike <ham789@netzero.net> - 2013-09-24 16:43 -0700
  Re: Counting 2ms long pulses on several input pins j.m.granville@gmail.com - 2013-09-24 17:32 -0700
    Re: Counting 2ms long pulses on several input pins Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2013-09-25 09:52 +0300
      Re: Counting 2ms long pulses on several input pins Don Y <this@isnotme.com> - 2013-09-25 00:09 -0700
        Re: Counting 2ms long pulses on several input pins j.m.granville@gmail.com - 2013-09-25 16:53 -0700

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