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68 lines
1.9 KiB
C++
68 lines
1.9 KiB
C++
/* Blink without Delay
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Turns on and off a light emitting diode (LED) connected to a digital
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pin, without using the delay() function. This means that other code
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can run at the same time without being interrupted by the LED code.
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The circuit:
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* LED attached from pin 13 to ground.
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* Note: on most Arduinos, there is already an LED on the board
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that's attached to pin 13, so no hardware is needed for this example.
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created 2005
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by David A. Mellis
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modified 8 Feb 2010
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by Paul Stoffregen
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modified 11 Nov 2013
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by Scott Fitzgerald
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This example code is in the public domain.
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http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
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*/
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// constants won't change. Used here to set a pin number :
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const int ledPin = 13; // the number of the LED pin
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// Variables will change :
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int ledState = LOW; // ledState used to set the LED
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// Generally, you should use "unsigned long" for variables that hold time
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// The value will quickly become too large for an int to store
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unsigned long previousMillis = 0; // will store last time LED was updated
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// constants won't change :
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const long interval = 1000; // interval at which to blink (milliseconds)
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void setup() {
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// set the digital pin as output:
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pinMode(ledPin, OUTPUT);
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}
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void loop()
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{
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// here is where you'd put code that needs to be running all the time.
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// check to see if it's time to blink the LED; that is, if the
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// difference between the current time and last time you blinked
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// the LED is bigger than the interval at which you want to
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// blink the LED.
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unsigned long currentMillis = millis();
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if(currentMillis - previousMillis >= interval) {
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// save the last time you blinked the LED
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previousMillis = currentMillis;
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// if the LED is off turn it on and vice-versa:
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if (ledState == LOW)
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ledState = HIGH;
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else
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ledState = LOW;
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// set the LED with the ledState of the variable:
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digitalWrite(ledPin, ledState);
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}
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}
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