如何設定開始時 LED 狀態是 OFF??

andywwf

我想程式開始前, LED 狀態是關閉的.
請問是如何設置??
Thankyou

1. // this constant won't change:
   
2. const int  buttonPin = 2;    // the pin that the pushbutton is attached to
   
3. const int ledPin = 13;       // the pin that the LED is attached to
   
4. 
   
5. // Variables will change:
   
6. int buttonPushCounter = 0;   // counter for the number of button presses
   
7. int buttonState = 0;         // current state of the button
   
8. int lastButtonState = 0;     // previous state of the button
   
9. 
   
10. void setup() {
    
11.   // initialize the button pin as a input:
    
12.   pinMode(buttonPin, INPUT);
    
13.   // initialize the LED as an output:
    
14.   pinMode(ledPin, OUTPUT);
    
15.   // initialize serial communication:
    
16.   Serial.begin(9600);
    
17. }
    
18. 
    
19. 
    
20. void loop() {
    
21.   // read the pushbutton input pin:
    
22.   buttonState = digitalRead(buttonPin);
    
23. 
    
24.   // compare the buttonState to its previous state
    
25.   if (buttonState != lastButtonState) {
    
26.     // if the state has changed, increment the counter
    
27.     if (buttonState == HIGH) {
    
28.       // if the current state is HIGH then the button went from off to on:
    
29.       buttonPushCounter++;
    
30.       Serial.println("on");
    
31.       Serial.print("number of button pushes: ");
    
32.       Serial.println(buttonPushCounter);
    
33.     } else {
    
34.       // if the current state is LOW then the button went from on to off:
    
35.       Serial.println("off");
    
36.     }
    
37.     // Delay a little bit to avoid bouncing
    
38.     delay(50);
    
39.   }
    
40.   // save the current state as the last state, for next time through the loop
    
41.   lastButtonState = buttonState;
    
42. 
    
43. 
    
44.   // turns on the LED every four button pushes by checking the modulo of the
    
45.   // button push counter. the modulo function gives you the remainder of the
    
46.   // division of two numbers:
    
47.   if (buttonPushCounter % 4 == 0) {
    
48.     digitalWrite(ledPin, HIGH);
    
49.   } else {
    
50.     digitalWrite(ledPin, LOW);
    
51.   }
    
52. 
    
53. }

复制代码

ArBug

// initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
后面再加一句
digitalWrite(ledPin, LOW);
因为你只是把灯设置成输出模式，但是并没有选择输出高还是输出低喔

andywwf

ArBug 发表于 2022-1-12 21:15
// initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
后面再加一句

你好!
我試了, 但不行喔...
明明是這樣設置, 就是不行, 想不通......

shouzama

andywwf 发表于 2022-1-12 22:13
你好!
我試了, 但不行喔...
明明是這樣設置, 就是不行, 想不通......

接線圖?
合理懷疑你的開關初始狀態就是 HIGH,
所以不必按開關就亮燈了

lwq1947

因为int buttonPushCounter = 0;所以if (buttonPushCounter % 4 == 0)条件成立,使得LED 狀態是ON.设置
int buttonPushCounter = -1;就满足你的要求了.

andywwf

lwq1947 发表于 2022-1-13 07:07
因为int buttonPushCounter = 0;所以if (buttonPushCounter % 4 == 0)条件成立,使得LED 狀態是ON.设置
int  ...

真的可以了, 謝謝您.
我問了好多人, 都解決不了呢.
原來是要用 - 來解決, 真是受教了.