arduino ibox项目实战14－按键控制LED灯实验（二）

armeasy

硬件平台：PC机一台，ibox卡片电脑一只，arduino扩展板一个

软件平台：WIN7操作系统，android4.0或android4.4系统

打开arduino的IDE开发工具，依次点击文件->示例->01.Basics->Debounce，Debounce的示例程序将会被打开，其源码如下：

1. // constants won't change. They're used here to
   
2. // set pin numbers:
   
3. const int buttonPin = KEY0;    // the number of the pushbutton pin 24(KEY0)
   
4. const int ledPin = LED1;      // the number of the LED pin 22(LED1)
   
5. 
   
6. // Variables will change:
   
7. int ledState = HIGH;         // the current state of the output pin
   
8. int buttonState;             // the current reading from the input pin
   
9. int lastButtonState = LOW;   // the previous reading from the input pin
   
10. 
    
11. // the following variables are long's because the time, measured in miliseconds,
    
12. // will quickly become a bigger number than can be stored in an int.
    
13. long lastDebounceTime = 0;  // the last time the output pin was toggled
    
14. long debounceDelay = 50;    // the debounce time; increase if the output flickers
    
15. 
    
16. void setup() {
    
17.   pinMode(buttonPin, INPUT);
    
18.   pinMode(ledPin, OUTPUT);
    
19. 
    
20.   // set initial LED state
    
21.   digitalWrite(ledPin, ledState);
    
22. }
    
23. 
    
24. void loop() {
    
25.   // read the state of the switch into a local variable:
    
26.   int reading = digitalRead(buttonPin);
    
27. 
    
28.   // check to see if you just pressed the button
    
29.   // (i.e. the input went from LOW to HIGH),  and you've waited
    
30.   // long enough since the last press to ignore any noise:
    
31. 
    
32.   // If the switch changed, due to noise or pressing:
    
33.   if (reading != lastButtonState) {
    
34.     // reset the debouncing timer
    
35.     lastDebounceTime = millis();
    
36.   }
    
37. 
    
38.   if ((millis() - lastDebounceTime) > debounceDelay) {
    
39.     // whatever the reading is at, it's been there for longer
    
40.     // than the debounce delay, so take it as the actual current state:
    
41. 
    
42.     // if the button state has changed:
    
43.     if (reading != buttonState) {
    
44.       buttonState = reading;
    
45. 
    
46.       // only toggle the LED if the new button state is HIGH
    
47.       if (buttonState == HIGH) {
    
48.         ledState = !ledState;
    
49.       }
    
50.     }
    
51.   }
    
52. 
    
53.   // set the LED:
    
54.   digitalWrite(ledPin, ledState);
    
55. 
    
56.   // save the reading.  Next time through the loop,
    
57.   // it'll be the lastButtonState:
    
58.   lastButtonState = reading;
    
59. }

复制代码

本程序将会采集按键数据，每按一次，将会对ledState取反一次。因此，按按一下ibox上中间的按钮，LED灯状态会变一次。注意，程序中两次通过if语句判断按键的状态，是用于消除按键抖动。否则，每按一次按键时，LED灯将会不断的开关数次，最终灯的状态也是未知的。