LDR sensor is a special resistor made of semiconductor materials such as sulfide or selenide. It is also coated with moisture-proof resin and has photoconductive effect.
LDR sensor are very sensitive to light. The stronger the light, the lower the resistance. With the increase of illumination intensity, the resistance value of the ldr photoresistor decreases rapidly, and it can be reduced to less than 1K.
The working principle of LDR sensor is based on the internal photoelectric effect, that is, the semiconductor photosensitive material is encapsulated in the shell with transparent window by installing electrode leads at both ends to form the LDR sensor. In order to increase sensitivity, the two electrodes are usually combed.
1. The module of the ldr light dependent resistor is most sensitive to the ambient light intensity, which is generally used to detect the ambient brightness and intensity.
2. When the module has no light condition or the light intensity can not reach the set threshold, the DO port outputs high level. When the light intensity of the external environment exceeds the set threshold, the module D0 outputs low level.
3. The digital output D0 of the small board can be directly connected with the single chip computer, which can detect the high and low levels, thereby detecting the change of light intensity in the environment.
4. AO output of small board analog can be connected with AD module. Through AD conversion, more accurate values of ambient light intensity can be obtained.