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Changed to pin 2 for consistency

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Tom Igoe 2009-06-25 18:04:56 +00:00
parent e5a4e5c66c
commit 12cc34e9e0
1 changed files with 55 additions and 46 deletions
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101
build/shared/dist/examples/Control/WhileStatementConditional/WhileStatementConditional.pde vendored
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@ -3,73 +3,82 @@
This example demonstrates the use of while() statements. This example demonstrates the use of while() statements.
It reads the state of a potentiometer (an analog input) and blinks an LED While the pushbutton is pressed, the sketch runs the calibration routine.
while the LED remains above a certain threshold level. It prints the analog value The sensor readings during the while loop define the minimum and maximum
only if it's below the threshold. of expected values from the photo resistor.
This example uses principles explained in the BlinkWithoutDelay example as well. This is a variation on the calibrate example.
The circuit: The circuit:
* potentiometer connected to analog pin 0. * photo resistor connected from +5V to analog in pin 0
Center pin of the potentiometer goes to the analog pin. * 10K resistor connected from ground to analog in pin 0
side pins of the potentiometer go to +5V and ground * LED connected from digital pin 9 to ground through 220 ohm resistor
* LED connected from digital pin 13 to ground * pushbutton attached from pin 2 to +5V
* 10K resistor attached from pin 2 to ground
* Note: On most Arduino boards, there is already an LED on the board
connected to pin 13, so you don't need any extra components for this example.
created 17 Jan 2009 created 17 Jan 2009
modified 25 Jun 2009
by Tom Igoe by Tom Igoe
*/ */
// These constants won't change:
const int analogPin = 0; // pin that the sensor is attached to
const int ledPin = 13; // pin that the LED is attached to
const int threshold = 400; // an arbitrary threshold level that's in the range of the analog input
const int blinkDelay = 500; // how long to hold between changes of the LED
// these variables will change: // These constants won't change:
int ledState = LOW; // the state of the LED const int sensorPin = 2; // pin that the sensor is attached to
int lastBlinkTime = 0; // last time the LED changed const int ledPin = 9; // pin that the LED is attached to
int analogValue; // variable to hold the value of the analog input 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() { void setup() {
// initialize the LED pin as an output: // set the LED pins as outputs and the switch pin as input:
pinMode(ledPin, OUTPUT); pinMode(indicatorLedPin, OUTPUT);
// initialize serial communications: pinMode (ledPin, OUTPUT);
Serial.begin(9600); pinMode (buttonPin, INPUT);
} }
void loop() { void loop() {
// read the value of the potentiometer: // while the button is pressed, take calibration readings:
analogValue = analogRead(analogPin); while (digitalRead(buttonPin) == HIGH) {
calibrate();
}
// signal the end of the calibration period
digitalWrite(indicatorLedPin, LOW);
// if the analog value is high enough, turn on the LED: // read the sensor:
while (analogValue > threshold) { sensorValue = analogRead(sensorPin);
// if enough time has passed since the last change of the LED,
// then change it. Note you're using the technique from BlinkWithoutDelay
// here so that the while loop doesn't delay the rest of the program:
if (millis() - lastBlinkTime > blinkDelay) { // apply the calibration to the sensor reading
// if the ledState is high, this makes it low, and vice versa: sensorValue = map(sensorValue, sensorMin, sensorMax, 0, 255);
ledState = !ledState;
digitalWrite(ledPin, ledState);
// save the last time the LED changed in a variable: // in case the sensor value is outside the range seen during calibration
lastBlinkTime = millis(); sensorValue = constrain(sensorValue, 0, 255);
}
// while you're in the while loop, you have to read the // fade the LED using the calibrated value:
// input again: analogWrite(ledPin, sensorValue);
analogValue = analogRead(analogPin); }
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;
} }
// if you're below the threshold, print the analog value: // record the minimum sensor value
Serial.println(analogValue, DEC); if (sensorValue < sensorMin) {
// turn the LED off: sensorMin = sensorValue;
digitalWrite(ledPin, LOW); }
} }