---
title: delay()
categories: [ "Functions" ]
subCategories: [ "Time" ]
---





= delay()


// OVERVIEW SECTION STARTS
[#overview]
--

[float]
=== Description
Pauses the program for the amount of time (in milliseconds) specified as parameter. (There are 1000 milliseconds in a second.)
[%hardbreaks]


[float]
=== Syntax
`delay(ms)`


[float]
=== Parameters
`ms`: the number of milliseconds to pause. Allowed data types: `unsigned long`.


[float]
=== Returns
Nothing

--
// OVERVIEW SECTION ENDS




// HOW TO USE SECTION STARTS
[#howtouse]
--

[float]
=== Example Code
// Describe what the example code is all about and add relevant code   ►►►►► THIS SECTION IS MANDATORY ◄◄◄◄◄
The code pauses the program for one second before toggling the output pin.

[source,arduino]
----
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
}
----
[%hardbreaks]

[float]
=== 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 link:http://arduino.cc/en/Tutorial/BlinkWithoutDelay[Blink Without Delay] sketch, which loops, polling the link:../millis[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 (link:../../analog-io/analogwrite[analogWrite]) values and pin states are maintained, and link:../../external-interrupts/attachinterrupt[interrupts] will work as they should.

--
// HOW TO USE SECTION ENDS


// SEE ALSO SECTION
[#see_also]
--

[float]
=== See also

[role="example"]
* #EXAMPLE# http://arduino.cc/en/Tutorial/BlinkWithoutDelay[Blink Without Delay^]

--
// SEE ALSO SECTION ENDS