A different twist on switch debounce

[MrDEB]

If I am interpreting this right then the DELAYMS(xxx) increases. Note I am not familiar with this code, assume its C??
Just browsing for tilt switches and found this.

    /* Better Debouncer
    *
    * This debouncing circuit is more rugged, and will work with tilt switches!
    *
    * http://www.ladyada.net/learn/sensor/tilt.html
    */
    int inPin = 2; // the number of the input pin
    int outPin = 13; // the number of the output pin
    int LEDstate = HIGH; // the current state of the output pin
    int reading; // the current reading from the input pin
    int previous = LOW; // the previous reading from the input pin
    // the follow variables are long's because the time, measured in miliseconds,
    // will quickly become a bigger number than can be stored in an int.
    long time = 0; // the last time the output pin was toggled
    long debounce = 50; // the debounce time, increase if the output flickers
    void setup()
    {
    pinMode(inPin, INPUT);
    digitalWrite(inPin, HIGH); // turn on the built in pull-up resistor
    pinMode(outPin, OUTPUT);
    }
    void loop()
    {
    int switchstate;
    reading = digitalRead(inPin);
    // If the switch changed, due to bounce or pressing...
    if (reading != previous) {
    // reset the debouncing timer
    time = millis();
    }
    if ((millis() - time) > debounce) {
    // whatever the switch is at, its been there for a long time
    // so lets settle on it!
    switchstate = reading;
    // Now invert the output on the pin13 LED
    if (switchstate == HIGH)
    LEDstate = LOW;
    else
    LEDstate = HIGH;
    }
    digitalWrite(outPin, LEDstate);
    // Save the last reading so we keep a running tally
    previous = reading;
    }

 

[Ian Rogers]

Its a snippet from an arduino sketch... Even 50mS for me is too short... But as he uses this for tilt switches I'm sure its good..

Normal debounce is 20 - 30mS.... With my keypad I use a beeper 100mS+ to acknowledge the keypress.... Works fine..

 

[MrDEB]

am I to assume that the delay increases by itself if the switch is closed?

 

[Ian Rogers]

The delay is for both... The check is... is the state of the switch the same as before.... No!! set milli to count to debounce time.. When counted.. set new state...