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76 lines
2.4 KiB
Plaintext
76 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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It reads the state of a potentiometer (an analog input) and blinks an LED
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while the LED remains above a certain threshold level. It prints the analog value
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only if it's below the threshold.
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This example uses principles explained in the BlinkWithoutDelay example as well.
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The circuit:
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* potentiometer connected to analog pin 0.
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Center pin of the potentiometer goes to the analog pin.
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side pins of the potentiometer go to +5V and ground
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* LED connected from digital pin 13 to ground
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* Note: On most Arduino boards, there is already an LED on the board
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connected to pin 13, so you don't need any extra components for this example.
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created 17 Jan 2009
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by Tom Igoe
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*/
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// These constants won't change:
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const int analogPin = 0; // pin that the sensor is attached to
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const int ledPin = 13; // pin that the LED is attached to
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const int threshold = 400; // an arbitrary threshold level that's in the range of the analog input
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const int blinkDelay = 500; // how long to hold between changes of the LED
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// these variables will change:
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int ledState = LOW; // the state of the LED
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int lastBlinkTime = 0; // last time the LED changed
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int analogValue; // variable to hold the value of the analog input
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void setup() {
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// initialize the LED pin as an output:
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pinMode(ledPin, OUTPUT);
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// initialize serial communications:
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Serial.begin(9600);
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}
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void loop() {
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// read the value of the potentiometer:
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analogValue = analogRead(analogPin);
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// if the analog value is high enough, turn on the LED:
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while (analogValue > threshold) {
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// if enough time has passed since the last change of the LED,
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// then change it. Note you're using the technique from BlinkWithoutDelay
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// here so that the while loop doesn't delay the rest of the program:
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if (millis() - lastBlinkTime > blinkDelay) {
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// if the ledState is high, this makes it low, and vice versa:
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ledState = !ledState;
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digitalWrite(ledPin, ledState);
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// save the last time the LED changed in a variable:
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lastBlinkTime = millis();
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}
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// while you're in the while loop, you have to read the
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// input again:
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analogValue = analogRead(analogPin);
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}
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// if you're below the threshold, print the analog value:
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Serial.println(analogValue, DEC);
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// turn the LED off:
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digitalWrite(ledPin, LOW);
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}
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