这是从网上找来的一个比较典型的PID处理程序，在使用单片机作为控制cpu时，请稍作简化，具体的PID参数必须由具体对象通过实验确定。-It is recruited from the Internet in a typical PID handler in the use of SCM as a control cpu, make some simplification, the specific PID parameters must be experimentally determined by specific objects.