一、我們都一樣

剛開始接觸物聯網時，都會遇到按照老師的操作，做得一模一樣，但是....怎麼動作與預期中的不一樣

尤其是按鈕：明明按下要亮，卻按了一兩次才做動一次正常...

其實是這樣的，這就是按鈕的bounce，當我們按鈕按下的時候，其實是數位訊號讀取了幾十次，會建議在序列埠當中加一個counter，然後把它列印出來....

您會發現counter列印出來的數字，每次您按下按鍵時候，不是每次都加一，可能是加了十或加了幾百...

二、以polling方式來解決bounce

所以先講解決之道吧

設定一個狀態的flag加delay秒數約50毫秒或100毫秒...

三、主動式外部中斷方式

山姆老師教得蠻清楚的...

完整程式碼：

#include "Arduino.h"

int  ledPin = 13;   // assign LED pin to number 13

int  digitalPin = 2;   // assign digital pin to number 2

bool bLedState = LOW; // initial LED state to LOW level

bool bBottonUP = true; // initial bottonUP flag

bool bHasINT0 = false; // initial INT0 flag

void setup()

{

    pinMode(ledPin, OUTPUT);     // initial LED pin to OUTPUT mode

    pinMode(digitalPin, INPUT);    // initial digital pin to INPUT mode

    digitalWrite(ledPin, bLedState); // setup LED state according to ledState

    Serial.begin(9600);

     while (!Serial){

      ; // wait for serial port to connect

     }

    Serial.println("Hello INT0");

    // config INT0 falling edge trigger (10) to generate interrupt by set EICRA

    EICRA |= _BV(ISC01);

    EICRA &= ~_BV(ISC00);

    // Enable INT0 interrupt by set EIMSK

    EIMSK |= _BV(INT0);

}

void loop()

{

 // read digital pin2 state and check bBottonUP

//  if ( digitalRead(digitalPin) == LOW && bBottonUP == true )

    if ( bHasINT0 && bBottonUP == true )

    {

     bLedState = ! bLedState;     // reverse LED state

     digitalWrite(ledPin, bLedState); // setup LED state according to ledState

     bBottonUP = false;

     delay(50);

    }

//  else if (digitalRead(digitalPin)== HIGH && bBottonUP == false)

    else if (bHasINT0 && bBottonUP == false)

    {

//   Serial.println("re-enable INT0");

     bBottonUP = true;

    bHasINT0 = false;

       // Re-enable INT0 interrupt by set EIMSK

       EIMSK |= _BV(INT0);

    }

}

ISR(INT0_vect)

{

 EIMSK &= ~_BV(INT0); // disable INT0

 bHasINT0 = true;  // Set flag

}