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软件消除抖动也是很常见的方式,一般形式是延时查询按键状态或者中断形式来消除抖动。
下面是Arduino的软件消抖代码： - /* SoftwareDebounce
- *
- * At each transition from LOW to HIGH or from HIGH to LOW
- * the input signal is debounced by sampling across
- * multiple reads over several milli seconds. The input
- * is not considered HIGH or LOW until the input signal
- * has been sampled for at least "debounce_count" (10)
- * milliseconds in the new state.
- *
- * Notes:
- * Adjust debounce_count to reflect the timescale
- * over which the input signal may bounce before
- * becoming steady state
- *
- * Based on:
- * http://www.arduino.cc/en/Tutorial/Debounce
- *
- * Jon Schlueter
- * 30 December 2008
- *
- * http://playground.arduino.cc/Learning/SoftwareDebounce
- */
- int inPin = 7; // the number of the input pin
- int outPin = 13; // the number of the output pin
- int counter = 0; // how many times we have seen new value
- int reading; // the current value read from the input pin
- int current_state = LOW; // the debounced input value
- // the following variable is a long because the time, measured in milliseconds,
- // will quickly become a bigger number than can be stored in an int.
- long time = 0; // the last time the output pin was sampled
- int debounce_count = 10; // number of millis/samples to consider before declaring a debounced input
- void setup()
- {
- pinMode(inPin, INPUT);
- pinMode(outPin, OUTPUT);
- digitalWrite(outPin, current_state); // setup the Output LED for initial state
- }
- void loop()
- {
- // If we have gone on to the next millisecond
- if(millis() != time)
- {
- reading = digitalRead(inPin);
- if(reading == current_state && counter > 0)
- {
- counter--;
- }
- if(reading != current_state)
- {
- counter++;
- }
- // If the Input has shown the same value for long enough let's switch it
- if(counter >= debounce_count)
- {
- counter = 0;
- current_state = reading;
- digitalWrite(outPin, current_state);
- }
- time = millis();
- }
- }
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