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Tom Igoe 2009-06-17 21:17:49 +00:00
parent 75385f5ff5
commit 0374c30460

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/* Blink without Delay /* Blink without Delay
*
* Turns on and off a light emitting diode(LED) connected to a digital Turns on and off a light emitting diode(LED) connected to a digital
* pin, without using the delay() function. This means that other code pin, without using the delay() function. This means that other code
* can run at the same time without being interrupted by the LED code. can run at the same time without being interrupted by the LED code.
*
* http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay The circuit:
* LED attached from pin 13 to ground.
* Note: on most Arduinos, there is already an LED on the board
that's attached to pin 13, so no hardware is needed for this example.
created 2005
by David A. Mellis
modified 17 Jun 2009
by Tom Igoe
http://www.arduino.cc/en/Tutorial/BlinkWithoutDelay
*/ */
int ledPin = 13; // LED connected to digital pin 13 // constants won't change. Used here to
int value = LOW; // previous value of the LED // set pin numbers:
const int ledPin = 13; // the number of the LED pin
// Variables will change:
int ledState = LOW; // ledState used to set the LED
long previousMillis = 0; // will store last time LED was updated long previousMillis = 0; // will store last time LED was updated
// the follow variables is a long because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long interval = 1000; // interval at which to blink (milliseconds) long interval = 1000; // interval at which to blink (milliseconds)
void setup() void setup() {
{ // set the digital pin as output:
pinMode(ledPin, OUTPUT); // sets the digital pin as output pinMode(ledPin, OUTPUT);
} }
void loop() void loop()
@ -25,14 +43,16 @@ void loop()
// between the current time and last time we blinked the LED bigger than // between the current time and last time we blinked the LED bigger than
// the interval at which we want to blink the LED. // the interval at which we want to blink the LED.
if (millis() - previousMillis > interval) { if (millis() - previousMillis > interval) {
previousMillis = millis(); // remember the last time we blinked the LED // save the last time you blinked the LED
previousMillis = millis();
// if the LED is off turn it on and vice-versa. // if the LED is off turn it on and vice-versa:
if (value == LOW) if (ledState == LOW)
value = HIGH; ledState = HIGH;
else else
value = LOW; ledState = LOW;
digitalWrite(ledPin, value); // set the LED with the ledState of the variable:
digitalWrite(ledPin, ledState);
} }
} }