Infrared IR Sensor Interface with PIC18F4550 Microcontroller

IR Sensor Interface with PIC18F4550 Microcontroller project - Digital Input

IR Sensor Interface with PIC18F4550

In my previous project we have made a simple IR sensor Circuit. In this project, as promised before – we are going to demonstrate a PIC18F4550 microcontroller interface to IR sensor circuit. We are just going to glow few on the pic18f4550 as an example, however you can do some more intelligent operations by adding some more logics to the microcontroller coding. Interfacing infrared Proximity sensors with Microcontroller is quiet easy.

This project is not only about interfacing an infrared IR sensor module but also we are going to learn - How to take digital input from a PIC18F4550 Microcontroller (Reading the Input with a Microcontroller). It means that the source code here will work same for taking input from a simple switch. You can replace the IR sensor with some simple PUSH Switch or some other types of proximity sensors . In case of push button you would need to pull down the pin to ground with 1 k resistance, however for IR sensor you won’t need to pull down the input pin with resistor.

Infrared IR Sensor Module

Let’s take a look at the IR Infrared Sensor Circuit Project module that we made in our previous project which is an inexpensive ( Low Cost ) sensor circuit module. You can find the schematic and PCB design in my previous post. There are three pins in the Schematic - Two pins for providing the input voltage and GND to the IR Sensor Module, and the third pin from the IR module is the IR control pin. This Control Pin from the IR sensor Module will be interfaced to the PIC18F4550 microcontroller for sensor input.

IR Sensor Module

Infrared IR sensor Object detection circuit Module design and pin settings


The output from the IR sensor circuit will be connected to pins of a PIC18f4550 microcontroller and the microcontroller will regard it as digital input to read either 1 or 0.  According to the output from the IR sensor module, the PIC18F4550 will respond by glowing led. Since we just want to read some voltage in the microcontroller as input (either High or low) hence we are going to configure input pins as digital to read just 1 or 0 from the sensor.

IR infrared Sensor circuit connected a with PIC18F4550 microcontroller project on breadboard Project: PIC18F4550 Microcontroller programming with IR sensor Module


PIC18F4550 Interface with IR sensor Circuit

The output from the IR sensor circuit is connected to RA0 of the pic18f4550 which is configured as input with TRISB registers, and the output will be displayed on LED connected across RD7, RD6,RD5 (PORTD) and RB0 and RB1 (PORTB) which are configured as output pins. Follow the schematic below.

Schematic (IR sensor and PIC18F4550 microcontroller)

Schematic for Infrared IR sensor circuit interfacing with a PIC18F4550 Microcontroller circuit

In this project we don’t need to perform any Analog to Digital Conversion(ADC), hence we are going to turn the ADC off (ADCON0bits.ADON = 0) and configure all the PINS to Digital.  At the default 1 MHZ oscillator frequency the output sometimes gives unstable result, hence tuning the microcontroller to 8MHZ solved the problem, Please note that pic18f4550 works by default on 1 MHZ and you can change the OSCCON bits settings to tune the oscillator frequency according to your requirement.

Search in pic18f4550 datasheet for OSCCON register bits and you will find a nice description and bits settings table for available oscillator frequency and settings to configure the microcontroller oscillator frequency. Here I have configured the internal oscillator to 8MHZ to avoid switch debouncing. However it works well with 1MHZ settings as well. As a better plan the comparator is also turned off to avoid any conflict.

                          All the resistors in the above Schematic is 1k resistance. If possible, it is also recommended to add a IC 7805 liner Voltage regulator IC as a source of +5V to avoid any voltage fluctuation which could possibly damage the microcontroller. Make sure the input voltage to pic18f4550 must never exceed +5v. Please do read the excellent pic18f4550 datasheet provided by microchip.

IR sensor circuit programmed with PIC18F4550 microcontroller as Digital Input pin

Source Code:

MPLAB IDE and C18 Compiler is used for compiling the source code, however MPLAB X IDE and XC8 Compiler can be also used with no difficulty. Download the entire project at the end of the source code below with compiled firmware. 

SOURCE CODE :infraredinput.c

 * File:   infraredinput.c
* Author: ron
 * December 10, 2012, 1:21 PM
#include <p18f4550.h>           // Include Header for PIC18F4550

#define switch1  PORTAbits.RA0  // Switch on RA0

#define led1    LATDbits.LATD7     // led1
#define led2    LATDbits.LATD6    // led2

#define led3    LATBbits.LATB0   // led3
#define led4    LATBbits.LATB1    // led4
#define led5    LATBbits.LATB2    // led5

void main (void)


            /* If you want your microcontroller to work at  1MHZ then comment the three lines below */

OSCCONbits.IRCF0 = 1 ;               // set internal clock to 8 MHz
OSCCONbits.IRCF1 = 1;                //  For Avoiding switch debouncing problem      
OSCCONbits.IRCF2= 1;                 //

/* Input output settings*/

       TRISAbits.TRISA0 = 1;                  //   RA0 Input for taking input from IR sensor

       TRISDbits.TRISD7 = 0;                  // Port D pins output
       TRISDbits.TRISD6 = 0;

       TRISBbits.TRISB0 = 0;                  // Port B pins Output
       TRISBbits.TRISB1 = 0;
       TRISBbits.TRISB2 = 0;

       CMCON = 0x07;           // Disable Comparator

       ADCON1bits.PCFG0 = 1;          // These 4 settings below determines the analog or digital input
       ADCON1bits.PCFG1 = 1;          // In our case we are making all the pins digital
       ADCON1bits.PCFG2 = 1;         // by setting them as 1111
       ADCON1bits.PCFG3 = 1;         // Check with the datasheet for a nice desc of these bits and config.

       ADCON0bits.ADON = 0;  //  Disabled ADC

     {   //Forever Loop
            if(switch1 == 1)    //   On reading IR sensor value ON
                    {    //Turn led ON
                                led1 = 1;
                                 led2 = 1;
                              led3 = 1;
                              led4 = 1;
                                 led5 = 1;              }
       else if ( switch1 == 0) // On reading IR Sensor Value OFF
                      {   //Turn led off
                              led1 = 0;
                            led2 = 0;
                            led3 = 0;
                            led4 = 0;
                            led5 = 0;              }
                                     else {    }

    }   //End While loop --forever

/* THE END */

The coding above is pretty much self-explanatory, and comment lines must be also helpful for better understanding.

Now you can use this project to develop your own application the way you want. It's easy to interface this project with a L293D Motor Driver to drive DC motors as an "IR sensor Motor Driver" or a simple IR infrared robot, or you could add one more IR module on some other AN pin as switch2, with which you can make it as "IR Line follower robot" very easily.In my next tutorial I have also shown how to interface multiple IR sensors with Arduino Uno board and have the status of the sensor displayed on LCD.

Use the way your creativity drives you.

Download the Full Project



Full Mplab IDE project (IR Digital input)

Mplab X IDE project (Digital Input)


Thanks for Reading
Rakesh Mondal

Previous Next


IR sensor circuit Programmed with PIC18F4550 Microcontroller, programming pic184550 for digital input