In this tutorial we will learn how to interface LDR with PIC Microcontroller. Here I am use PIC16F877A Microcontroller and 5mm LDR.

You can watch the video or read the written tutorial below.

LDR mean Light Dependent Resisor. It resistance depend on visible light. The LDR resistance Negative Co-efficient of Light. When visible light intensity is increase than the LDR resistance is decrease.

LDR Resistance can be change (0.50 to 2.50)K.

In this project I am set 2.50K resistance for LDR.. Here I am use voltage divider circuit to provide MCU analog voltage.

Voltage Divider Rule:

Source Code:

float adc_value;
float voltage;
void main() {
     TRISA.F0 = 1;           // RA0/AN0 is analog input
     TRISB.F7 = 0;             // RB7 is output
     ADC_Init();               // Initialize adc module
     while(1){
              adc_value = Adc_Read(0);             // RA0 Pin is analog input
              voltage = (adc_value * 5 ) /1023;
              if(voltage >= 1){
                         PORTB.F7 = 1;
                         }
              else {
                          PORTB.F7 = 0;
                          }
              delay_ms(100);
              }
}

Download free source code

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