LDR Light Dependent Resistor Sensor interfacing
with Arduino, Node MCU, ESP32 operates blinds to adjust the light inside the room using linear Actuator
Light Dependent Resistor is called by many names such as photoresistor, photocell, photoconductor, photoconductive cells. The resistivity of LDR depends on the light incident on it and the sensitivity of LDR depends on the wavelength of the incident light. Thus it is a light sensitive device. Mostly it is used in circuits to detect the presence of the level of the light. There are many symbols. The most commonly used symbol of LDR is shown in the figure. The arrow in the symbol indicates the light falling on it.
LDR Light Dependent Resistor Sensor interfacing with Arduino:
VCC and GND are connected to 5 volts DC and ground of Arduino. The voltage across LDR in the voltage or resistance dividing network is brought out as Analog output A0 which is connected to Analog input of Arduino A0 to which ADC (Analog to Digital Converter) is internally connected. D0 is connected to Arduino digital Pin 7 which will turn on Digital Pin 9 which is connected to relay which switches on LED Bulb. Then there are two LEDs and one buzzer connected to Pin 2, Pin 3 and Pin 4 respectively. Pin 2 is connected to Green LED which will switch on as soon as power is switch on to indicate Arduino is on. Red LED and Buzzer will be on when Pin 7 goes high.