arduino 按钮阅读
示例
这是一个基本示例，说明如何在按下按钮时进行接线并使LED亮/灭。
/* Basic Digital Read
* ------------------
*
* turns on and off a light emitting diode(LED) connected to digital
* pin 13, when pressing a pushbutton attached to pin 7. It illustrates the
* concept of Active-Low, which consists in connecting buttons using a
* 1K to 10K pull-up resistor.
*
* Created 1 December 2005
* copyleft 2005 DojoDave <http://www.0j0.org>
* http://arduino.berlios.de
*
*/
int ledPin = 13; //选择LED的引脚
int inPin = 7; //选择输入引脚（用于按钮）
int val = 0; //用于读取引脚状态的变量
void setup() {
pinMode(ledPin, OUTPUT); //声明LED为输出
pinMode(inPin, INPUT); //声明按钮为输入
}
void loop(){
val = digitalRead(inPin); //读取输入值
if (val == HIGH) { //检查输入是否为高（释放按钮）
digitalWrite(ledPin, LOW); //关闭LED
} else {
digitalWrite(ledPin, HIGH); //打开LED
}
}取自Arduino.cc的示例。