# 亮滅自保 debounce ```c++= // 程式介紹 int ledState; // LED狀態，沒賦值，預設為0 int buttonState; // 0.001豪秒以前，按鈕狀態 int lastButtonState; // 0.001豪秒以前，按鈕狀態 unsigned long ChangeTime; // 按按鈕的時間點 unsigned long debounceDelay = 50; // 用50ms debounce void setup() { pinMode(2, INPUT); pinMode(13, OUTPUT); } void loop() { int now = digitalRead(2);//現在按鈕狀態 if (now != lastButtonState) //!=不等於 //現在按鈕狀態 不等於 0.001毫秒以前按鈕狀態 //按了按鈕 //if滿足條件 執行下面一行 //如果有兩行 要用{ }包住 ChangeTime = millis(); //millis() 系統開機時間 //系統開機開始記錄時間 以毫秒為單位 約可記錄50天 //超過50天 從0從新紀錄時間 //按了按鈕 記錄當下的時間點 if ((millis() - ChangeTime) > debounceDelay) //系統時間-按按鈕時間 > 50ms //例如587-501 >50 //消除雜訊 消除電路彈跳 消抖debounce if (now != buttonState) //現在按鈕狀態 不等於 0.001豪秒以前，按鈕狀態 //按了按鈕 { buttonState = now; if (now == HIGH) ledState = !ledState;//!0就是1 !1就是0 } digitalWrite(13, ledState); lastButtonState = now; } ``` ```c++= void loop() { //1.燈滅，沒按按鈕 int now = digitalRead(2); //now=0 if (now != lastButtonState) //0!=0 不成立 不執行 ChangeTime = millis(); //不執行 if ((millis() - ChangeTime) > debounceDelay) // 約138-0 > 50 成立 if (now != buttonState) //0!=0 不成立 不執行 { buttonState = now; //不執行 if (buttonState == HIGH) //不執行 ledState = !ledState; //不執行 } digitalWrite(13, ledState); //燈滅 lastButtonState = now; //lastButtonState= 0 } ``` ```c++= void loop() { //2.燈滅，按按鈕，燈亮 int now = digitalRead(2); //now=1 if (now != lastButtonState) //1!=0 成立 ChangeTime = millis(); //ChangeTime= 約2657 if ((millis() - ChangeTime) > debounceDelay) // 約2721-2657 > 50 成立 if (now != buttonState) //1!=0 成立 { buttonState = now; //buttonState = 1 if (buttonState == HIGH) //1=1成立 ledState = !ledState; //0=!0=1=亮 } digitalWrite(13, ledState); //燈亮 lastButtonState = now; //lastButtonState= 1 } ``` ```c++= void loop() { //3.燈亮，不按按鈕 int now = digitalRead(2); //now=0 if (now != lastButtonState) //0!=1 不成立 ChangeTime = millis(); //不執行 if ((millis() - ChangeTime) > debounceDelay) // 約4567-2657 > 50 成立 if (now != buttonState) //0!=1 成立 { buttonState = now; //buttonState = 0 if (buttonState == HIGH) //0=1不成立 不執行 ledState = !ledState; //不執行 } digitalWrite(13, ledState); //ledState=1 燈亮 lastButtonState = now; //lastButtonState= 0 } ``` ```c++= void loop() { //4.燈亮，按按鈕，燈滅 int now = digitalRead(2); //now=1 if (now != lastButtonState) //1!=0 成立 ChangeTime = millis(); //ChangeTime= 約12657 if ((millis() - ChangeTime) > debounceDelay) // 約12721-12657 > 50 成立 if (now != buttonState) //1!=0 成立 { buttonState = now; //buttonState = 1 if (buttonState == HIGH) //1=1成立 ledState = !ledState; //1= !1= 0= 滅 } digitalWrite(13, ledState); //ledState=0 燈滅 lastButtonState = now; //lastButtonState= 1 } ``` ```c++= void loop() { //5約=1.燈滅，沒按按鈕 int now = digitalRead(2); //now=0 if (now != lastButtonState) //0!=1 成立 ChangeTime = millis(); //ChangeTime= 約13456 if ((millis() - ChangeTime) > debounceDelay) // 約13511-13456 > 50 成立 if (now != buttonState) //0!=1 成立 { buttonState = now; //buttonState = 0 if (buttonState == HIGH) //0=1 不成立不執行 ledState = !ledState; //不執行 } digitalWrite(13, ledState); //ledState=0 燈滅 lastButtonState = now; //lastButtonState= 0 } ```