说明：  本代码主要实现arduino板子跟asratch软件进行通讯。scratch软件里打开传感器监视窗口，可以看到里面有8个传感器都被检测到。由于外部真是传感器需要接到arduino上面，所以本代码里去掉了传感器的真实代码，方便大家可以接各类传感器。
(Code mainly realize the arduino board told asratch software to communicate. scratch software open sensor monitors window, you can see that there are eight sensors are detected. Due the external really arduino sensors need to be connected to the above, the code removed the real code of the sensor to facilitate various types of sensors can be connected.)