资源包括传感器的代码和所用的粉尘传感器的资料，简述一下所用传感器是传回低电平，芯片检测到低电平的时间占30s的百分比，对照所给资料得到粉尘浓度。结果是由串口输出，仅给各位提供思路。若有问题，请各位指正，谢谢。所用芯片是stm32f103。(The resource includes the code of sensor and the data of dust sensor. The sensor is sent back to low level. The percentage of time