Color Detection Using RGB LED

78,223

68

35

About: ECE student at Carnegie Mellon University.
Have you ever wanted an automated way to detect the color of an object? By shining light of a certain color on the object and looking at how much light is reflected back, you can tell what color the object is. For example, if you shine a red light on a red object, that light will be reflected back. If you shine a blue light on a red object, the object will absorb some of that light and less of it will be reflected back.



Step 1: Parts Needed

I used a PIC 16F887 Microcontroller, but almost any with a pulse-width-modulation capability will work.

1 RGB LED
1 Microcontroller
1 Standard red LED
1 1k ohm resistor
1 Photoresistor (changes resistance depending on the amount of light shone on it)
Some wires

I only need the microcontroller and RGB LED to have a wide range of color detectors, but if you only want a circuit that detects one color, you don't need a microcontroller - you only need a bright LED of the color you want to detect. The standard red LED is the "indicator LED" - it lights up when the right color is detected.

Step 2: Build the Circuit

The schematic is rather simple, and in general form, is shown below. The RGB LED is externally powered by a PWM signal.

I put electrical tape around the photoresistor so ambient light doesn't get in - only the light directly above it will be detected.

Step 3: The Code

This code was written for a Microchip PIC 16F887, but hopefully you can get the general idea. I used the built-in potentiometer on my development board to vary the color spectrum of the RGB LED (and it doesn't go through the entire spectrum because I don't have 3 PWM modules, but it's good enough)

Comments included.

#include <16F887.h>
#include <delay.h>
#include "delay.c"
#include <stdlib.h>
#include <STRING.h>

#use delay(clock = 4000000)
#FUSES INTRC,NOWDT,NOPUT,NOMCLR,NOPROTECT,NOCPD,NOBROWNOUT,NOIESO,NOFCMEN,NOLVP
#byte CCP1CON = 0x17
#byte CCP2CON = 0x1D
#byte PWM1CON = 0x9B

int value = 128;
int p1 = 0;
int p2 = 0;

void my_setup_ccp1(int8 value)
{
output_low(PIN_C2);
CCP1CON = value;
PWM1CON = 0;
}

void my_setup_ccp2(int8 value)
{
output_low(PIN_C1);
CCP2CON = value;
}

//===================================
void main()
{
//A4 = power source for photodiode
output_high(PIN_A4);
output_high(PIN_B1);
setup_adc(ADC_CLOCK_INTERNAL);
set_adc_channel(0);
setup_adc_ports(sAN0);

//Timer/Interrupt setup
enable_interrupts(INT_TIMER2);

my_setup_ccp1(CCP_PWM);
my_setup_ccp2(CCP_PWM);

setup_timer_2(T2_DIV_BY_1, 128, 1);
//setup_compare(2,COMPARE_PWM|COMPARE_TIMER2);

while(1){ // Prevent PIC from going to sleep.
//SET PWM DUTY CYCLE
output_high(PIN_A5);
//Pin A3 is the photodiode connection
if(input(PIN_A3) == 1)
output_high(PIN_A4);
else
output_low(PIN_A4);
//Read value of potentiometer to change color of LED
value = read_adc();
switch (value) {

case 0:
p1 = value;
output_low(PIN_C0);
p2 = value;
break;
case 50:
p1 = value;
output_high(PIN_C0);
p2 = value;
break;
case 100:
p1 = value;
output_high(PIN_C0);
p2 = value;
break;
case 150:
output_high(PIN_C0);
p1 = 50;
p2 = value;
break;
case 200:
output_low(PIN_C0);
p1 = 0;
p2 = value;
break;
case 250:
p1 = 0;
p2 = value;
output_low(PIN_C0);
break;
}

p1 = value;
p2 = 128 - p1;

set_pwm1_duty(p1);
set_pwm2_duty(p2);
}
}

Step 4: Applications!

A simple color detector like this can be used in robotics, or for cool projects like separating legos by color, sorting M&Ms, or as an aid for color blindness.

Hopefully this instructable was helpful in enhancing a project you had in mind! :) LEDs are good for so many things....

Share

    Recommendations

    • Epilog X Contest

      Epilog X Contest
    • Comfort Food Challenge

      Comfort Food Challenge
    • Safe and Secure Challenge

      Safe and Secure Challenge

    35 Discussions

    0
    None
    blueorbcleaning

    2 years ago

    Good afternoon

    I
    want to know if you have a color identify sensor that support android ?

    like an android app can integrate with that sensor because I
    want the voice from android app to tell what color is this

    Looking forward hearing from you .

    Thanks

    please contact back 00971 52 610 3200

    Thanks

    1 reply
    0
    None
    Tryfon

    2 years ago

    it is very interesting i have a assignment i will provide a brief report of 1 – 2 pages (length for guidance only) documenting the best strategy for interfacing the colour sensor with the microprocessor pic 18f 2455 . my decision should be clearly justified and the next step is to carry out design work on the code and produce a set of design notes which may include:

     a flow chart of the operation of the program,

     a list of the I/O pin allocations

     A list of the subroutines you will use.

     Pseudocode outline for your program

    can you help do you have any idea????

    email trikomo2014@gmail.com

    vlachouli

    00306937007704

    0
    None
    BrentW14

    2 years ago

    Hi i would like to make something to detect red with a possible alarm on it.. how would i go about that? Thanks

    0
    None
    sunil vishwakarma

    2 years ago

    hii i'm sunil now i wana to more information aboout color sensor & if i don't follows to th RBG rule then the how to work the sensor

    and accepted to other colors VGO working

    pls tell me sir its my project work

    0
    None
    AndrewP112

    3 years ago

    I am making a similar device to detect a compound that illuminates one color (orange) under black light. My plan is to use a blue LED to excite the compound and an orange LED to sense it. Does anyone see any problem with this logic? Thanks.

    0
    None
    svaladez1

    5 years ago on Introduction

    Hi, may I have full scheme for you color sensor...
    My e-mail is cristysonia@yahoo.com

    0
    None
    UNGUREANU

    5 years ago on Introduction

    hi..could you send me the schematic for this project..my email is razvan_spyd3r@yahoo.com..thank you

    0
    None
    mtaqmilly

    5 years ago on Introduction

    Can i have your full scheme for color detection...
    My email mtaqmilly@gmail.com

    0
    None
    aimamo

    6 years ago on Introduction

    awsome!
    Can i have your full scheme for color detection...
    My email : dbestworld90@gmail.com.
    thank you..

    0
    None
    macxfady

    6 years ago on Introduction


    Thks for the info..recently im doing the colour detection circuit
    plz send me a schematic diagrams of full project.
    my email: macxfady@gmail.com
    thank you

    0
    None
    ongjq

    6 years ago on Introduction

    Thks for the info..recently im doing the colour detection circuit..can i have a copy of your schematic diagrams..this is my mail: ongjiaqing@hotmail.com..thks a lot..

    0
    None
    naveenraikar

    7 years ago on Introduction

    Plz send me full scheme for color detection...
    My email id is: sraikar_naveen@yahoo.com

    0
    None
    setu

    8 years ago on Introduction

    its great...but u have to change every time the led light to sense the color ...actually i want to design a color sensor for my project which can sense RGB colors continuously without any need of changing led light every time...if there is a way plz tell me....my id : sunlitesetu@gmail.com

    0
    None
    vojkann

    8 years ago on Introduction

    hi.... can you send me full scheme for color detection.. :D
    It would be good if you send it to me... :D
    here is my email: vojkann@gmail.com