【【计算机大侠】Arduino教程：按键消抖】https://toutiao.com/group/6703127408653894152/?app=explore_article×tamp=1560724254&req_id=201906170630530101520170937899F97&group_id=6703127408653894152&tt_from=copy_link&utm_source=copy_link&utm_medium=toutiao_ios&utm_campaign=client_share
防抖当按下时，按键经常产生错误的开/关变迁，这是机械物理的问题：这些变迁可能被读取为在短时间内多次按下，从而使程序变笨。这个例子示范了怎样使一个输入防抖，这意味着在一个短时间内检查两次来确保这个按键是确实被按下了。如果没有防抖，按一次这个按键可能会引起不可预测的结果。这个程序利用millis（）函数来保持按下的时间间隔。
按键消抖原理
当按下时，按键经常产生错误的开/关变化，这是机械物理的问题：这些变化可能被读取为在短时间内多次按下，从而使程序变笨。这个例子示范了怎样使一个输入防抖，这意味着在一个短时间内检查两次来确保这个按键是确实被按下了。如果没有防抖，按一次这个按键可能会引起不可预测的结果。这个程序利用millis（）函数来保持按下的时间间隔。
硬件要求
- Arduino or Genuino 开发板
- 即时按键或者开关
- 10k ohm 电阻
- 连接线
- 面包板
代码
例子里，当闭合时开关为低电平，而断开时开关未高电平。这里当按下开关时为高电平，没有按下时为低电平。
// constants won't change. They're used here to// set pin numbers:const int buttonPin = 2; // the number of the pushbutton pinconst int ledPin = 13; // the number of the LED pin// Variables will change:int ledState = HIGH; // the current state of the output pinint buttonState; // the current reading from the input pinint lastButtonState = LOW; // the previous reading from the input pin// the following variables are long's because the time, measured in miliseconds,// will quickly become a bigger number than can be stored in an int.long lastDebounceTime = 0; // the last time the output pin was toggledlong debounceDelay = 50; // the debounce time; increase if the output flickersvoid setup() { pinMode(buttonPin, INPUT); pinMode(ledPin, OUTPUT); // set initial LED state digitalWrite(ledPin, ledState);}void loop() { // read the state of the switch into a local variable: int reading = digitalRead(buttonPin); // check to see if you just pressed the button // (i.e. the input went from LOW to HIGH), and you've waited // long enough since the last press to ignore any noise: // If the switch changed, due to noise or pressing: if (reading != lastButtonState) { // reset the debouncing timer lastDebounceTime = millis(); } if ((millis() - lastDebounceTime) > debounceDelay) { // whatever the reading is at, it's been there for longer // than the debounce delay, so take it as the actual current state: // if the button state has changed: if (reading != buttonState) { buttonState = reading; // only toggle the LED if the new button state is HIGH if (buttonState == HIGH) { ledState = !ledState; } } } // set the LED: digitalWrite(ledPin, ledState); // save the reading. Next time through the loop, // it'll be the lastButtonState: lastButtonState = reading;}
