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Tutorials with Arduino: Led controlled by photo sensor

This has been my first project  Arduino UNO. It´s a very simple project, controlling the intenisty of a light with a photoresistor. As darker it gets, the stronger the light will get, and the brighter it gets, the light goes down. Here is a video of the project working: http://youtu.be/pCRhzh3d6ww Part List:

  • 1 x  Arduino UNO
  • 1 x photosensor
  • 1 x 10k resist
  • 1 x 220 ohm resist
  • 1 x breadboard

arduino + photosensor     The source code is based on this tutorial:: www.ladyada.net/learn/sensors/cds.html with a few tweaks. /* Photocell Led. * ————– * * @author: Javier Lander * @hardware: Javier Lander * www.mrlndr.com * twitter: @mrlndr */ int photocellPin = 3; // the cell and 10K pulldown are connected to a0 int photocellReading; // the analog reading from the sensor divider int LEDpin = 11; // connect Red LED to pin 11 (PWM pin) int LEDbrightness; // void setup(void) { // We’ll send debugging information via the Serial monitor Serial.begin(9600); } void loop(void) { photocellReading = analogRead(photocellPin); Serial.print(“Analog reading = “); Serial.println(photocellReading); // the raw analog reading // LED gets brighter the darker it is at the sensor // that means we have to -invert- the reading from 0-1023 back to 1023-0 photocellReading = 1023 – (photocellReading); //now we have to map 0-1023 to 0-255 since thats the range analogWrite uses LEDbrightness = map(photocellReading, 0, 1023, 0, 255); analogWrite(LEDpin, LEDbrightness); Serial.print(“Led = “); Serial.println(LEDbrightness); // the raw analog reading delay(10); }

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2 Comments

  1. I would like to have an Arduino to program it for controlling a solar panel system for powering a whole home, by driving 2 axis sun tracking of the solar cells and monitoring voltages and currents to the loads or battery chargers/inverters. I would be very pleased if i win one of these Arduinos Uno R3.