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Arduino/build/shared/examples/Control/WhileStatementConditional/WhileStatementConditional.pde
2009-07-11 00:34:59 +00:00

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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
*/
// 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;
}
}