Subject:
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software debouncing (was Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 25 Aug 1999 22:00:36 GMT
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Viewed:
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587 times
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> > One VERY easy method is to take successive samples at an interval
> > greater than the switch bounce (from the spec sheet for the switch)
> > and just make sure you have two identical readings before processing
> > it as a state change...
In lugnet.robotics, lego-robotics@crynwr.com (Jim Thomas) writes:
> [...] Debouncing multiplexed switches in software is more
> difficult than you proposed unless you make some limiting assumptions.
The way I debounce is by using a simulated RC network ("RC" stands for
resistor-capacitor). RC networks exhibit a "decaying exponential" response to
an input waveform. Here is an example of how to simulate an RC network:
averagereading = 0;
while (true) {
Sleep(1); /* take readings every 1/100 second */
rawreading = SensorInput();
/* The "+ 2" is for rounding */
/* Change "4" and "5" to "10" and "11" to make it respond more slowly */
averagereading = ((4 * averagereading) + rawreading + 2) / 5;
if (averagereading > THRESHOLD1) {
/* beep */
} else if (averagereading < THRESHOLD2) {
/* burp */
}
}
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