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87 lines
2.4 KiB
Plaintext
87 lines
2.4 KiB
Plaintext
/*
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Conditionals - while statement
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This example demonstrates the use of while() statements.
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While the pushbutton is pressed, the sketch runs the calibration routine.
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The sensor readings during the while loop define the minimum and maximum
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of expected values from the photo resistor.
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This is a variation on the calibrate example.
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The circuit:
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* photo resistor connected from +5V to analog in pin 0
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* 10K resistor connected from ground to analog in pin 0
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* LED connected from digital pin 9 to ground through 220 ohm resistor
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* pushbutton attached from pin 2 to +5V
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* 10K resistor attached from pin 2 to ground
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created 17 Jan 2009
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modified 25 Jun 2009
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by Tom Igoe
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http://arduino.cc/en/Tutorial/WhileLoop
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*/
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// These constants won't change:
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const int sensorPin = 2; // pin that the sensor is attached to
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const int ledPin = 9; // pin that the LED is attached to
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const int indicatorLedPin = 13; // pin that the built-in LED is attached to
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const int buttonPin = 2; // pin that the button is attached to
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// These variables will change:
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int sensorMin = 1023; // minimum sensor value
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int sensorMax = 0; // maximum sensor value
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int sensorValue = 0; // the sensor value
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void setup() {
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// set the LED pins as outputs and the switch pin as input:
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pinMode(indicatorLedPin, OUTPUT);
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pinMode (ledPin, OUTPUT);
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pinMode (buttonPin, INPUT);
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}
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void loop() {
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// while the button is pressed, take calibration readings:
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while (digitalRead(buttonPin) == HIGH) {
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calibrate();
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}
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// signal the end of the calibration period
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digitalWrite(indicatorLedPin, LOW);
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// read the sensor:
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sensorValue = analogRead(sensorPin);
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// apply the calibration to the sensor reading
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sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);
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// in case the sensor value is outside the range seen during calibration
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sensorValue = constrain(sensorValue, 0, 255);
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// fade the LED using the calibrated value:
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analogWrite(ledPin, sensorValue);
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}
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void calibrate() {
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// turn on the indicator LED to indicate that calibration is happening:
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digitalWrite(indicatorLedPin, HIGH);
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// read the sensor:
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sensorValue = analogRead(sensorPin);
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// record the maximum sensor value
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if (sensorValue > sensorMax) {
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sensorMax = sensorValue;
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}
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// record the minimum sensor value
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if (sensorValue < sensorMin) {
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sensorMin = sensorValue;
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}
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}
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