(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/03.Analog/AnalogInput/AnalogInput.ino lang=arduino tabwidth=4:)

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/3.Analog/AnalogInput/AnalogInput.ino lang=arduino tabwidth=4:)

(:source http://github.com/arduino/Arduino/raw/new-extension/build/shared/examples/3.Analog/AnalogInput/AnalogInput.ino lang=arduino tabwidth=4:)

Analog Input

For this example, it is possible to use the Arduino board's built in LED attached to pin 13. To use an additional LED, attach its longer leg (the positive leg, or anode), to digital pin 13, and it's shorter leg (the negative leg, or cathode) to the ground (gnd) pin next to pin 13. Because of the low amount of current coming from digital pin 13, it is not necessary to use a current limiting resistor in this particular case.

In the beginning of this program, the variable sensorPin is set to to analog pin 0, where your potentiometer is attached, and ledPin is set to digital pin 13. You'll also create another variable, sensorValue i to store the values read from your sensor.

The analogRead() command converts the input voltage range, 0 to 5 volts, to a digital value between 0 and 1023. This is done by a circuit inside the Arduino called an analog-to-digital converter or ADC.

By turning the shaft of the potentiometer, you change the amount of resistance on either side of the center pin (or wiper) of the potentiometer. This changes the relative resistances between the center pin and the two outside pins, giving you a different voltage at the analog input. When the shaft is turned all the way in one direction, there is no resistance between the center pin and the pin connected to ground. The voltage at the center pin then is 0 volts, and analogRead() returns 0. When the shaft is turned all the way in the other direction, there is no resistance between the center pin and the pin connected to +5 volts. The voltage at the center pin then is 5 volts, and analogRead() returns 1023. In between, analogRead() returns a number between 0 and 1023 that is proportional to the amount of voltage being applied to the pin.

A potentiometer is a simple knob that provides a variable resistance, which you can read into the Arduino board as an analog value. In this example, you'll connect a poterntiometer to one of the Arduino's analog inputs to control the rate at which the built-in LED on pin 13 blinks.

Hardware Required

A potentiometer is a simple knob that provides a variable resistance, which we can read into the Arduino board as an analog value. In this example, you'll connect a poterntiometer to one of the Arduino's analog inputs to control the rate at which the built-in LED on pin 13 blinks.

• built-in LED on pin 13

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/3.Analog/AnalogInput/AnalogInput.pde lang=arduino tabwidth=4:)

Hardware Required

• Arduino Board
• Potentiometer

Connect three wires to the Arduino board. The first goes to ground from one of the outer pins of the potentiometer. The second goes from 5 volts to the other outer pin of the potentiometer. The third goes from analog input 0 to the middle pin of the potentiometer.

For this example, it is possible to use the Arduino board's built in, small, surface mount LED attached to pin 13. To use an additional LED, attach it's long, positive leg (the anode), to digital pin 13, and it's shorter negative leg (the cathode) to the ground (gnd) pin right near by. Because of the low amount of current coming from digital pin 13, it is not necessary to use a current limiting resistor in this particular case.

In the beginning of this program, the variable sensorPin is assigned to your potentiometer on analog pin 0, while ledPin is set to digital pin 13. Another variable, sensorValue is created to store the data that will be retrieved from your sensor.

By turning the shaft of the potentiometer, we change the amount of resistence on either side of the wiper which is connected to the center pin of the potentiometer. This changes the relative "closeness" of that pin to 5 volts and ground, giving us a different analog input. When the shaft is turned all the way in one direction, there are 0 volts going to the pin, and we read 0. When the shaft is turned all the way in the other direction, there are 5 volts going to the pin and we read 1023. In between, analogRead() returns a number between 0 and 1023 that is proportional to the amount of voltage being applied to the pin.

That value, stored in sensorValue, is used to set a delay() for your blink cycle. The higher the value, the longer the cycle, the smaller the value, the shorter the cycle.

(:divend:)

See Also:

• pinMode()
• analogRead()
• digitalWrite()
• delay()

• AnalogReadSerial - read a potentiometer, print it's state to the serial monitor
• AnalogInOutSerial - read an analog input, map its values, and then use that information to dim or brighten an LED.
• Fade - use an analog input to fade an LED
• Calibration - calibrating analog sensor readings

 (:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/3.Analog/AnalogInput/AnalogInput.pde lang=arduino  tabwidth=4:)

 (:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/Analog/AnalogInput/AnalogInput.pde lang=arduino  tabwidth=4:)

image developed using Fritzing. For more circuit examples, see the Fritzing project page

(:div class=code :)

 /*
   Analog Input
  Demonstrates analog input by reading an analog sensor on analog pin 0 and
  turning on and off a light emitting diode(LED)  connected to digital pin 13. 
  The amount of time the LED will be on and off depends on
  the value obtained by analogRead(). 
  
  The circuit:
  * Potentiometer attached to analog input 0
  * center pin of the potentiometer to the analog pin
  * one side pin (either one) to ground
  * the other side pin to +5V
  * LED anode (long leg) attached to digital output 13
  * LED cathode (short leg) attached to ground
  
  * Note: because most Arduinos have a built-in LED attached 
  to pin 13 on the board, the LED is optional.
  
  
  Created by David Cuartielles
  Modified 16 Jun 2009
  By Tom Igoe
  
  http://arduino.cc/en/Tutorial/AnalogInput
  
  */

 int sensorPin = 0;    // select the input pin for the potentiometer
 int ledPin = 13;      // select the pin for the LED
 int sensorValue = 0;  // variable to store the value coming from the sensor

 void setup() {
   // declare the ledPin as an OUTPUT:
   pinMode(ledPin, OUTPUT);  
 }

 void loop() {
   // read the value from the sensor:
   sensorValue = analogRead(sensorPin);    
   // turn the ledPin on
   digitalWrite(ledPin, HIGH);  
   // stop the program for <sensorValue> milliseconds:
   delay(sensorValue);          
   // turn the ledPin off:        
   digitalWrite(ledPin, LOW);   
   // stop the program for for <sensorValue> milliseconds:
   delay(sensorValue);                  
 }

(:divend:)

Circuit

An analog input connected to analog input pin 0.

click the image to enlarge

Schematic

click the image to enlarge

  Analog Input
 Demonstrates analog input by reading an analog sensor on analog pin 0 and
 turning on and off a light emitting diode(LED)  connected to digital pin 13. 
 The amount of time the LED will be on and off depends on
 the value obtained by analogRead(). 

 The circuit:
 * Potentiometer attached to analog input 0
 * center pin of the potentiometer to the analog pin
 * one side pin (either one) to ground
 * the other side pin to +5V
 * LED anode (long leg) attached to digital output 13
 * LED cathode (short leg) attached to ground

 * Note: because most Arduinos have a built-in LED attached 
 to pin 13 on the board, the LED is optional.

 Created by David Cuartielles
 Modified 16 Jun 2009
 By Tom Igoe

 http://arduino.cc/en/Tutorial/AnalogInput

int sensorPin = 0; // select the input pin for the potentiometer int ledPin = 13; // select the pin for the LED int sensorValue = 0; // variable to store the value coming from the sensor

  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);  

  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);    
  // turn the ledPin on
  digitalWrite(ledPin, HIGH);  
  // stop the program for <sensorValue> milliseconds:
  delay(sensorValue);          
  // turn the ledPin off:        
  digitalWrite(ledPin, LOW);   
  // stop the program for for <sensorValue> milliseconds:
  delay(sensorValue);                  

Examples > Analog I/O

Analog Input

A potentiometer is a simple knob that provides a variable resistance, which we can read into the Arduino board as an analog value. In this example, that value controls the rate at which an LED blinks.

We connect three wires to the Arduino board. The first goes to ground from one of the outer pins of the potentiometer. The second goes from 5 volts to the other outer pin of the potentiometer. The third goes from analog input 2 to the middle pin of the potentiometer.

By turning the shaft of the potentiometer, we change the amount of resistence on either side of the wiper which is connected to the center pin of the potentiometer. This changes the relative "closeness" of that pin to 5 volts and ground, giving us a different analog input. When the shaft is turned all the way in one direction, there are 0 volts going to the pin, and we read 0. When the shaft is turned all the way in the other direction, there are 5 volts going to the pin and we read 1023. In between, analogRead() returns a number between 0 and 1023 that is proportional to the amount of voltage being applied to the pin.

Circuit

Code

/*
 * AnalogInput
 * by DojoDave <http://www.0j0.org>
 *
 * Turns on and off a light emitting diode(LED) connected to digital  
 * pin 13. The amount of time the LED will be on and off depends on
 * the value obtained by analogRead(). In the easiest case we connect
 * a potentiometer to analog pin 2.
 */

int potPin = 2;    // select the input pin for the potentiometer
int ledPin = 13;   // select the pin for the LED
int val = 0;       // variable to store the value coming from the sensor

void setup() {
  pinMode(ledPin, OUTPUT);  // declare the ledPin as an OUTPUT
}

void loop() {
  val = analogRead(potPin);    // read the value from the sensor
  digitalWrite(ledPin, HIGH);  // turn the ledPin on
  delay(val);                  // stop the program for some time
  digitalWrite(ledPin, LOW);   // turn the ledPin off
  delay(val);                  // stop the program for some time
}