delay()

Description

Pauses the program for the amount of time (in milliseconds) specified as parameter. (There are 1000 milliseconds in a second.)

Syntax

delay(ms)

Parameter Values

  • ms: the number of milliseconds to pause. Allowed data types: unsigned long.

Return Values

  • Nothing

Example Code

The code pauses the program for one second before toggling the output pin.

int ledPin = 13; // LED connected to digital pin 13 void setup() { pinMode(ledPin, OUTPUT); // sets the digital pin as output } void loop() { digitalWrite(ledPin, HIGH); // sets the LED on delay(1000); // waits for a second digitalWrite(ledPin, LOW); // sets the LED off delay(1000); // waits for a second }

※ NOTES AND WARNINGS:

While it is easy to create a blinking LED with the delay() function and many sketches use short delays for such tasks as switch debouncing, the use of delay() in a sketch has significant drawbacks. No other reading of sensors, mathematical calculations, or pin manipulation can go on during the delay function, so in effect, it brings most other activity to a halt. For alternative approaches to controlling timing see the Blink Without Delay sketch, which loops, polling the millis() function until enough time has elapsed. More knowledgeable programmers usually avoid the use of delay() for timing of events longer than 10's of milliseconds unless the Arduino sketch is very simple.

Certain things do go on while the delay() function is controlling the Atmega chip, however, because the delay function does not disable interrupts. Serial communication that appears at the RX pin is recorded, PWM (analogWrite) values and pin states are maintained, and interrupts will work as they should.

See Also

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