giovedì 26 giugno 2014

Arduino color detector

Hi guys I'm here with a really nice project: recognise colors with arduino.
It uses a particular property of colors:
The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. (from wikipedia)
First of all we are talking about objects which don't emit light by themselves.
Then we know that the color we sense is the light that an object reflects, so:
if we know exactly the quantity of light that goes to an object and then with a sensor we measure the quantity that has been reflected we can know the color of the object.
The main "problems" are two: we have to do this 3 times (for red, green, blue light), the result is influenced by sources of light we can't control (environmental lights).
The solution to the first problem is simply the repetition of the code three time; for the second problem we have to make a calibration for the sensor.
This calibration consist of gathering the maximum and the minimum light that an object can reflect in this particular environment (we have to do also this 3 times).

you'll nedd:
-an arduino
-an RGB led
-a photoresistor
-2x 10Kohm resistor
-a 220ohm resistor
-a pushbutton
then assemble everything this way:

Here is the arduino code:

Color detector with arduino, RGB led and photoresistor
Code by Damiano Andreghetti (also thanks to the adafruit tutorial about the RGB led)
for more information check my blog:

Everyone is free to use this code, but I would appreciate if you mention my name

int redPin = 11;
int greenPin = 9;
int bluePin = 10;
int buttonPin = 2;
int buttonState = 0;
int phrPin = 0; //photoresistor pin

//other variables for calibrating and measuring
float calwr, calwg, calwb, calbr, calbg, calbb, r, g, b = 0;

//uncomment this line if using a Common Anode LED

void setup(){
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(bluePin, OUTPUT);
  pinMode(buttonPin, INPUT);
  pinMode(phrPin, INPUT);
void loop(){
  buttonState = digitalRead(buttonPin);
  if(buttonState == 0){
    Serial.println("button pressed: calibrating white");  

float readColor(int times){
  float avg, total, current = 0;
  for(int n = 0; n <= times; n++){
    current = analogRead(phrPin);
    total += current;
  avg = total/times;
  return avg;

void setColor(int red, int green, int blue){
  red = 255 - red;
  green = 255 - green;
  blue = 255 - blue;
  analogWrite(redPin, red);
  analogWrite(greenPin, green);
  analogWrite(bluePin, blue);

This function is needed because the raw measure is influenced by
environmental light.
void calibration(){
  //first calibrate with white color
  setColor(255, 0, 0);
  calwr = readColor(7);
  setColor(0, 255, 0);
  calwg = readColor(7);
  setColor(0, 0, 255);
  calwb = readColor(7);
  setColor(0, 0, 0);
  //then wait until the button is pressed again
  //so we can calibrate with black color
  Serial.println("waiting to calibrate black");
  for(int i = 0; i <= 10; i+=0){
    buttonState = digitalRead(buttonPin);
    if(buttonState == 0){  
      //calibrate with black color
      setColor(255, 0, 0);
      calbr = readColor(7);
      setColor(0, 255, 0);
      calbg = readColor(7);
      setColor(0, 0, 255);
      calbb = readColor(7);
      setColor(0, 0, 0);
      i = 20;
void measure(){
  float deltacal = 0;
  setColor(255, 0, 0);
  deltacal = calwr-calbr;
  r = (readColor(7) - calbr)/(deltacal)*255;
  setColor(0, 255, 0);
  deltacal= calwg-calbg;
  g = (readColor(7) - calbg)/(deltacal)*255;
  setColor(0, 0, 255);
  deltacal = calwb-calbb;
  b = (readColor(7) - calbb)/(deltacal)*255;

Now upload this code to the arduino.
To calibrate the sensor press one time the button (the sketch check the button status before the red light) while a white object is near the sensor, then the led turns off.
Now put a black object near the sensor and push the button another time.

The arduino will start writing via serial the RGB value it detects.

Now we're going to use processing to display the result.
Here is a simple sketch:

Sketch used to display the result of the color detector made with arduino
Code by Damiano Andreghetti based on processing serial
for more information and for the arduino schematic and code
check my blog:

Everyone is free to use this code, but I would appreciate if you mention my name

import processing.serial.*;

Serial port;  // Create object from Serial class
String buff;  // Data received from the serial port
int r,g,b = 0;

void setup() {
  size(600, 600);
  // List all the available serial ports in the output pane.
  // You will need to choose the port that the Wiring board is
  // connected to from this list. The first port in the list is
  // port #0 and the third port in the list is port #2.


  // use your port
  port = new Serial(this, Serial.list()[1], 9600);

void draw() {
  if (0 < port.available()) { 
    buff = port.readString();
    String[] list = split(buff, ',');
    if(list.length == 3){
      r = int(list[0]);
      g = int(list[1]);
      b = int(list[2]);

To make everything work connect the arduino, calibrate the sensor, and run the processing sketch.
If there are some problems re-calibrate the sensor and use a dark-color cylinder to isolate LED and resistor from the environment. Like this:

Here are other photos of the project:

Here is also a video of the project:

I hope you like this post, if you have any question comment or send me an email to

Bye, Dami

martedì 10 giugno 2014

Timelapse tutorial (with arduino and digital reflex camera)

Hi guys, today I'll talk about making a timelapse video.
For those who don't know what's a timelapse video, here  is mine:

First of all the components:
-digital camera (nikon, canon, olympus, pentax, sony)
-arduino (any board, UNO, MEGA, duemilanove ecc..)
-IR transmitter led
-220 ohm resistor

For making a timelapse video our camera has to take a photo from the same position each 15/20 sec (depending on what you're trying to do) and probably you don't want to take each picture by yourself, so you'll need an arduino.
First of all connect the led and the resistor to the arduino in this way:

Then using this really nice library our Arduino will shut photos.
Install the library and open arduino IDE.
Then go to File>Examples>MultiCameraIrControl and select your camera brand.
Now just change the loop function like this:

void loop(){

delay function will wait the give milliseconds before shutting another photo; I think 10 seconds are good for many videos but depending on your subject you would have to change this value.

Another part of this project is powering arduino and camera for many hours.
For the camera use the normal power supply and for the arduino I suggest using a 110V/220V--->USB transformer (probably you have one at home, they are used for smartphones or other devices).

The last part of the project is calculating how long we can shoot depending on delay between photos and camera's memory.

For example if I have a 32GB SD and I take a photo every 10 seconds (5MB each photos) I'll be able to shoot photos for: (32'000MB / 5MB ) * 10 sec

Make your own calculation but remember: this works only in theory: there are other variables (battery duration ecc..)

Now you just need to turn on your camera, turn on the remote control mode (look in the instructions), power the arduino and place it in front of your camera as a remote control.

Here is my short timelapse:

I hope you enjoyed this project, if you have any question comment or send me an email to

Bye, Dami

giovedì 5 giugno 2014

A teenager's reflections

Hi, this post isn't about any project, i'll just explain some reflections I made.
In the last year I quite left blogging, probably since I had the awareness of what blogging meant to me, I started knowing that blogging was really important for me.
I started thinking "blogging will be my life and also Arduino and electronics, I'll be famous for this, people will talk about my blog" but I didn't like this future for me, I imagined something different (and still I do).
So I started leaving blogging.
But now I know why I used to like this hobby: it makes me able to express what I think (like in this article), it makes me really happy when I see people from Russia/Singapore/ecc..  visiting my blog.
And also just because I was doing something well that didn't mean it would be my entire life, I mean: I'm just me, Damiano, a 16 years old boy who posts on a blog.
Bye, Dami