LDR SENSOR MODULE is sensitive to the light and can give output in digital and analog. The Photoresistor module is sensitive to ambient light, generally used to detect the brightness of the ambient light and environment, triggering microcontroller or relay module. When the outside ambient light intensity exceeds a set threshold, DO-ended output will be low, DO output can be directly connected with the microcontroller to detect high and low, thereby detecting ambient light levels change, the output can directly drive DO through relay module, which can be composed of a light control switch.