arduino ibox项目实战15－按键状态检测实验

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

实验目标：通过ibox中间的按键控制LED1的亮灭，要求每按四次按键，LED灯亮一次，如此反复循环。

打开arduino的IDE开发工具，依次点击文件->示例->02.Digital-> StateChangeDetection，StateChangeDetection的示例程序将会被打开，其源码如下：

1. // this constant won't change:
   
2. const int  buttonPin = KEY0;    // the pin that the pushbutton is attached to 24(KEY0)
   
3. const int ledPin = LED1;       // the pin that the LED is attached to 22(LED1)
   
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. void loop() {
    
20.   // read the pushbutton input pin:
    
21.   buttonState = digitalRead(buttonPin);
    
22. 
    
23.   // compare the buttonState to its previous state
    
24.   if (buttonState != lastButtonState) {
    
25.     // if the state has changed, increment the counter
    
26.     if (buttonState == LOW) {
    
27.       // if the current state is HIGH then the button
    
28.       // wend from off to on:
    
29.       buttonPushCounter++;
    
30.       Serial.println("on");
    
31.       Serial.print("number of button pushes:  ");
    
32.       Serial.println(buttonPushCounter);
    
33.     }
    
34.     else {
    
35.       // if the current state is HIGH then the button
    
36.       // wend from on to off:
    
37.       Serial.println("off");
    
38.     }
    
39.     // Delay a little bit to avoid bouncing
    
40.     delay(50);
    
41.   }
    
42.   // save the current state as the last state,
    
43.   //for next time through the loop
    
44.   lastButtonState = buttonState;
    
45.   // turns on the LED every four button pushes by
    
46.   // checking the modulo of the button push counter.
    
47.   // the modulo function gives you the remainder of
    
48.   // the division of two numbers:
    
49.   if (buttonPushCounter % 4 == 0) {
    
50.     digitalWrite(ledPin, HIGH);
    
51.   } else {
    
52.     digitalWrite(ledPin, LOW);
    
53.   }
    
54. }

复制代码

       首先在setup函数中将按键IO设置为输入，LED控制IO设置为输出，然后在loop函数中读取按键状态，每当按键从高到低变化一次，则buttonPushCounter加1，如果buttonPushCounter能够被4整除，说明已经按了四次，则将LED灯点亮，否则关闭LED灯，从而实现预期的效果。