Photoresistor Light Sensor Module

LDR module can detect visible light.

Description

The Photoresistor Light Sensor Module can detect the presence or absence and the relative strength of visible light.

PACKAGE INCLUDES:

• Photosensor Light Sensor Module

KEY FEATURES OF PHOTORESISTOR LIGHT SENSOR MODULE:

• Detects visible light spectrum
• Analog output
• 3.3 and 5V compatible

This module incorporates an photoresistor, also called an LDR (Light Dependent Resistor).  A photoresistor is a resistor whose resistance changes with the amount of light striking it.

The photoresistor is in series with a 10K resistor to create a voltage divider.  The output of the module is analog and is at a high voltage when no light is striking the sensor and the voltage lowers as the light intensity increases.  Under strong lighting, the output will approach ground.  When the light is completely blocked, the output will approach Vcc.

Module Connections

There is a 3-pin header on the assembly for making connections.

1 x 3 Header 

• ‘-‘ = Ground
• Center pin = Vcc (3.3 – 5V)
• S = Signal output connects to analog input pin on microcontroller

Note:  The power and ground leads can be reversed if you want the output voltage to decrease with decreasing light rather increasing. 

OUR EVALUATION RESULTS:

This is a basic module that can be used to experiment with a number of different types of applications which uses the presence or absence or relative strength of light to take an action.

The output of the sensor is fairly linear, but the accuracy is not sufficient to measure the absolute strength of light. It is best used to detect the presence or absence of light or to a get rough idea of how much light is striking the sensor.

The simple program below reads the output of the sensor and outputs the raw data to the Serial Monitor window.  Change lighting on the sensor to see the effect.

The sensor is connected to A0 in the program, but this can be any analog input pin.

Photoresistor Light Sensor Module Test Program

/*
Photoresistor Light Sensor Module Test

Basic code for reading the analog output of the light sensor module
*/
const int ANALOGPIN = A0;  // Set to any analog input pin
int rawValue = 0;          // Returned ADC reading from sensor

//===============================================================================
//  Initialization
//===============================================================================
void setup() 
{ 
  pinMode (ANALOGPIN, INPUT);
  Serial.begin(9600);         // Set comm speed for debug window messages
}

//===============================================================================
//  Main
//===============================================================================
void loop() 
{
  rawValue = analogRead (ANALOGPIN);  // Read sensor input
  Serial.print ("Reading Raw: ");
  Serial.println (rawValue);
  delay (1000);
}

BEFORE THEY ARE SHIPPED, THESE MODULES ARE:

• Sample inspected and tested per incoming shipment.

Notes: 

1. None

Technical Specifications