尽管造书去做的。但还是有莫名的成就感
从串口显示出，电压变化，
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
}
void loop() {
// put your main code here, to run repeatedly:
int val=analogRead(A0);
Serial.println(val);
delay(500);
}
原文：http://www.cnblogs.com/llguanli/p/6919096.html
