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diff --git a/source/lang/delay.rst b/source/lang/delay.rst new file mode 100644 index 0000000..90ca268 --- /dev/null +++ b/source/lang/delay.rst @@ -0,0 +1,72 @@ +.. highlight:: cpp + +.. _lang-delay: + +delay() +======= + +Pauses the program for at least a given number of milliseconds. (There +are 1000 milliseconds in a second.) + +Library Documentation +--------------------- + +.. doxygenfunction:: delay + + +Discussion +---------- + +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 :ref:`millis() <lang-millis>` function +and the "Blink Without Delay" sketch cited :ref:`below +<lang-delay-seealso>`\ . More knowledgeable programmers usually +avoid the use of ``delay()`` for timing of events longer than tens of +milliseconds, unless the sketch is very simple. + +Certain things *do* go on while the ``delay()`` function is +controlling the STM32 chip, however, because the delay function does +not disable interrupts. Serial communication that appears at the RX +pin is recorded, PWM (see :ref:`pwmWrite() <lang-pwmwrite>`\ ) values +and pin states are maintained, and :ref:`interrupts +<lang-attachinterrupt>` will work as they should. + + +Example +------- + +:: + + int ledPin = 13; // LED connected to 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 + } + +.. _lang-delay-seealso: + +See also +-------- + + +- :ref:`millis() <lang-millis>` +- :ref:`micros() <lang-micros>` +- :ref:`delayMicroseconds() <lang-delayMicroseconds>` +- (Arduino) `Blink Without Delay + <http://arduino.cc/en/Tutorial/BlinkWithoutDelay>`_ example (works + unmodified on Maple) + + +.. include:: cc-attribution.txt |