Tutorial.WhileLoop History

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May 02, 2012, at 04:05 PM by Scott Fitzgerald -
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November 16, 2011, at 04:17 AM by Scott Fitzgerald -
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September 30, 2011, at 03:19 AM by Scott Fitzgerald -
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September 17, 2010, at 11:57 PM by Christian Cerrito -
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September 17, 2010, at 11:39 PM by Christian Cerrito -
September 17, 2010, at 11:38 PM by Christian Cerrito -
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Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor.

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Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor.

September 17, 2010, at 10:49 PM by Tom Igoe -
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September 17, 2010, at 10:49 PM by Tom Igoe -
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September 17, 2010, at 10:47 PM by Tom Igoe -
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September 16, 2010, at 10:16 PM by Tom Igoe -
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September 16, 2010, at 09:18 AM by Christian Cerrito -
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September 16, 2010, at 09:17 AM by Christian Cerrito -
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September 16, 2010, at 08:58 AM by Christian Cerrito -
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Analog sensor (e.g. potentiometer, light sensor) on analog input 2. LED on digital pin 9.

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Connect your analog sensor (e.g. potentiometer, light sensor) on analog input 2 with a 10K ohm resistor to ground. Connect your button to digital pin, again with a 10K ohm resistor to ground. Connect your LED to digital pin 9, with a 220 ohm resistor in series.

September 16, 2010, at 08:55 AM by Christian Cerrito -
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Hardware Required

  • Arduino Board
  • (1) digital pushbutton or switch
  • (1) photocell, or analog sensor
  • (2) 10k ohm resistors
  • breadboard
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September 16, 2010, at 08:06 AM by Christian Cerrito -
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September 16, 2010, at 08:06 AM by Christian Cerrito -
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September 16, 2010, at 01:53 AM by Christian Cerrito -
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February 24, 2010, at 04:09 AM by Tom Igoe -
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 /*
   Conditionals - while statement
  
  This example demonstrates the use of  while() statements.
  
  While the pushbutton is pressed, the sketch runs the calibration routine.
  The  sensor readings during the while loop define the minimum and maximum 
  of expected values from the photo resistor.
  
  This is a variation on the calibrate example.
  
  The circuit:
  * photo resistor connected from +5V to analog in pin 0
  * 10K resistor connected from ground to analog in pin 0
  * LED connected from digital pin 9 to ground through 220 ohm resistor
  * pushbutton attached from pin 2 to +5V
  * 10K resistor attached from pin 2 to ground
  
  created 17 Jan 2009
  modified 25 Jun 2009
  by Tom Igoe
  
  http://arduino.cc/en/Tutorial/WhileLoop
  
  */
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Deleted lines 35-95:
 // These constants won't change:
 const int sensorPin = 2;     // pin that the sensor is attached to
 const int ledPin = 9;        // pin that the LED is attached to
 const int indicatorLedPin = 13;  // pin that the built-in LED is attached to
 const int buttonPin = 2;      // pin that the button is attached to

 // These variables will change:
 int sensorMin = 1023;  // minimum sensor value
 int sensorMax = 0;     // maximum sensor value
 int sensorValue = 0;         // the sensor value

 void setup() {
   // set the LED pins as outputs and the switch pin as input:
   pinMode(indicatorLedPin, OUTPUT);
   pinMode (ledPin, OUTPUT);
   pinMode (buttonPin, INPUT);
 }

 void loop() {
   // while the button is pressed, take calibration readings:
   while (digitalRead(buttonPin) == HIGH) {
     calibrate(); 
   }
   // signal the end of the calibration period
   digitalWrite(indicatorLedPin, LOW);  

   // read the sensor:
   sensorValue = analogRead(sensorPin);

   // apply the calibration to the sensor reading
   sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);

   // in case the sensor value is outside the range seen during calibration
   sensorValue = constrain(sensorValue, 0, 255);

   // fade the LED using the calibrated value:
   analogWrite(ledPin, sensorValue);
 }

 void calibrate() {
   // turn on the indicator LED to indicate that calibration is happening:
   digitalWrite(indicatorLedPin, HIGH);
   // read the sensor:
   sensorValue = analogRead(sensorPin);

   // record the maximum sensor value
   if (sensorValue > sensorMax) {
     sensorMax = sensorValue;
   }

   // record the minimum sensor value
   if (sensorValue < sensorMin) {
     sensorMin = sensorValue;
   }
 }

August 27, 2009, at 08:47 PM by Tom Igoe -
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image developed using Fritzing. For more circuit examples, see the Fritzing project page

July 05, 2009, at 07:24 PM by Tom Igoe -
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[@ /*

  Conditionals - while statement
to:
Deleted line 56:
 This example demonstrates the use of  while() statements.
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 While the pushbutton is pressed, the sketch runs the calibration routine.
 The  sensor readings during the while loop define the minimum and maximum 
 of expected values from the photo resistor.
to:
 // These constants won't change:
 const int sensorPin = 2;     // pin that the sensor is attached to
 const int ledPin = 9;        // pin that the LED is attached to
 const int indicatorLedPin = 13;  // pin that the built-in LED is attached to
 const int buttonPin = 2;      // pin that the button is attached to
Deleted line 63:
 This is a variation on the calibrate example.
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 The circuit:
 * photo resistor connected from +5V to analog in pin 0
 * 10K resistor connected from ground to analog in pin 0
 * LED connected from digital pin 9 to ground through 220 ohm resistor
 * pushbutton attached from pin 2 to +5V
 * 10K resistor attached from pin 2 to ground
to:
 // These variables will change:
 int sensorMin = 1023;  // minimum sensor value
 int sensorMax = 0;     // maximum sensor value
 int sensorValue = 0;         // the sensor value
Deleted lines 69-71:
 created 17 Jan 2009
 modified 25 Jun 2009
 by Tom Igoe
Changed lines 71-136 from:
 http://arduino.cc/en/Tutorial/WhileLoop

 */

// These constants won't change: const int sensorPin = 2; // pin that the sensor is attached to const int ledPin = 9; // pin that the LED is attached to const int indicatorLedPin = 13; // pin that the built-in LED is attached to const int buttonPin = 2; // pin that the button is attached to

// These variables will change: int sensorMin = 1023; // minimum sensor value int sensorMax = 0; // maximum sensor value int sensorValue = 0; // the sensor value

void setup() {

  // set the LED pins as outputs and the switch pin as input:
  pinMode(indicatorLedPin, OUTPUT);
  pinMode (ledPin, OUTPUT);
  pinMode (buttonPin, INPUT);

}

void loop() {

  // while the button is pressed, take calibration readings:
  while (digitalRead(buttonPin) == HIGH) {
    calibrate(); 
  }
  // signal the end of the calibration period
  digitalWrite(indicatorLedPin, LOW);  

  // read the sensor:
  sensorValue = analogRead(sensorPin);

  // apply the calibration to the sensor reading
  sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);

  // in case the sensor value is outside the range seen during calibration
  sensorValue = constrain(sensorValue, 0, 255);

  // fade the LED using the calibrated value:
  analogWrite(ledPin, sensorValue);

}

void calibrate() {

  // turn on the indicator LED to indicate that calibration is happening:
  digitalWrite(indicatorLedPin, HIGH);
  // read the sensor:
  sensorValue = analogRead(sensorPin);

  // record the maximum sensor value
  if (sensorValue > sensorMax) {
    sensorMax = sensorValue;
  }

  // record the minimum sensor value
  if (sensorValue < sensorMin) {
    sensorMin = sensorValue;
  }

}

@]

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June 25, 2009, at 11:35 PM by Tom Igoe -
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Analog sensor (e.g. potentiometer, light sensor) on analog input 2. LED on digital pin 9.

June 25, 2009, at 09:06 PM by Tom Igoe -
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 http://arduino.cc/en/Tutorial/WhileLoop
June 25, 2009, at 08:56 PM by Tom Igoe -
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Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate? the value of an analog sensor.

to:

Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor.

June 25, 2009, at 08:56 PM by Tom Igoe -
Changed lines 5-6 from:

Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor.

to:

Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate? the value of an analog sensor.

June 25, 2009, at 08:55 PM by Tom Igoe -
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Schematic:

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Schematic:

click the image to enlarge

June 25, 2009, at 08:11 PM by Tom Igoe -
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Code

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Examples > Control Structures

While Loop

Sometimes you want everything in the program to stop while a given condition is true. You can do this using a while loop. This example shows how to use a while loop to calibrate the value of an analog sensor.

In the main loop, the sketch below reads the value of a photoresistor on analog pin 0 and uses it to fade an LED on pin 9. But while a button attached to digital pin 2 is pressed, the program runs a method called calibrate() that looks for the highest and lowest values of the analog sensor. When you release the button, the sketch continues with the main loop.

This technique lets you update the maximum and minimum values for the photoresistor when the lighting conditions change.

Circuit

Schematic:

click the image to enlarge

Code

June 25, 2009, at 08:06 PM by Tom Igoe -
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Code

/*
  Conditionals - while statement

 This example demonstrates the use of  while() statements.

 While the pushbutton is pressed, the sketch runs the calibration routine.
 The  sensor readings during the while loop define the minimum and maximum 
 of expected values from the photo resistor.

 This is a variation on the calibrate example.

 The circuit:
 * photo resistor connected from +5V to analog in pin 0
 * 10K resistor connected from ground to analog in pin 0
 * LED connected from digital pin 9 to ground through 220 ohm resistor
 * pushbutton attached from pin 2 to +5V
 * 10K resistor attached from pin 2 to ground

 created 17 Jan 2009
 modified 25 Jun 2009
 by Tom Igoe

 */


// These constants won't change:
const int sensorPin = 2;     // pin that the sensor is attached to
const int ledPin = 9;        // pin that the LED is attached to
const int indicatorLedPin = 13;  // pin that the built-in LED is attached to
const int buttonPin = 2;      // pin that the button is attached to


// These variables will change:
int sensorMin = 1023;  // minimum sensor value
int sensorMax = 0;     // maximum sensor value
int sensorValue = 0;         // the sensor value


void setup() {
  // set the LED pins as outputs and the switch pin as input:
  pinMode(indicatorLedPin, OUTPUT);
  pinMode (ledPin, OUTPUT);
  pinMode (buttonPin, INPUT);
}

void loop() {
  // while the button is pressed, take calibration readings:
  while (digitalRead(buttonPin) == HIGH) {
    calibrate(); 
  }
  // signal the end of the calibration period
  digitalWrite(indicatorLedPin, LOW);  

  // read the sensor:
  sensorValue = analogRead(sensorPin);

  // apply the calibration to the sensor reading
  sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);

  // in case the sensor value is outside the range seen during calibration
  sensorValue = constrain(sensorValue, 0, 255);

  // fade the LED using the calibrated value:
  analogWrite(ledPin, sensorValue);
}

void calibrate() {
  // turn on the indicator LED to indicate that calibration is happening:
  digitalWrite(indicatorLedPin, HIGH);
  // read the sensor:
  sensorValue = analogRead(sensorPin);

  // record the maximum sensor value
  if (sensorValue > sensorMax) {
    sensorMax = sensorValue;
  }

  // record the minimum sensor value
  if (sensorValue < sensorMin) {
    sensorMin = sensorValue;
  }
}




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