delay()
Description
Pauses the program for the amount of time (in miliseconds) specified as parameter. (There are 1000 milliseconds in a second.)
Syntax
delay(ms)
Parameters
ms: the number of milliseconds to pause (unsigned long)
Returns
nothing
Example
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
}
Caveat
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 millis() function and the sketch sited below. 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 86Duino’s CPU 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
－ millis()
－ micros()
－ delayMicroseconds()
－ Blink Without Delay example
The text of the 86Duino reference is a modification of the Arduino reference, and is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.
