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Diffstat (limited to 'docs/source/arduino/delay.rst')
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1 files changed, 34 insertions, 61 deletions
diff --git a/docs/source/arduino/delay.rst b/docs/source/arduino/delay.rst index 973c75b..644e8c4 100644 --- a/docs/source/arduino/delay.rst +++ b/docs/source/arduino/delay.rst @@ -1,35 +1,40 @@ +.. highlight:: cpp + .. _arduino-delay: delay() ======= -Description ------------ - -Pauses the program for the amount of time (in miliseconds) -specified as parameter. (There are 1000 milliseconds in a second.) - - - -Syntax ------- +Pauses the program for at least a given number of milliseconds. (There +are 1000 milliseconds in a second.) -delay(ms) +Library Documentation +--------------------- +.. doxygenfunction:: delay -Parameters +Discussion ---------- -ms: the number of milliseconds to pause (*unsigned long*) - - - -Returns -------- - -nothing - +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() <arduino-millis>` function +and the "Blink Without Delay" sketch cited :ref:`below +<arduino-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() <wirish-pwmwrite>`\ ) +values and pin states are maintained, and :ref:`interrupts +<arduino-attachinterrupt>` will work as they should. Example @@ -37,58 +42,26 @@ Example :: - int ledPin = 13; // LED connected to digital pin 13 + int ledPin = 13; // LED connected to pin 13 - void setup() - { + void setup() { pinMode(ledPin, OUTPUT); // sets the digital pin as output } - void loop() - { + 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() <http://arduino.cc/en/Reference/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 Atmega chip however, because the delay function does not -disable interrupts. Serial communication that appears at the RX pin -is recorded, PWM -(`analogWrite <http://arduino.cc/en/Reference/AnalogWrite>`_) -values and pin states are maintained, and -`interrupts <http://arduino.cc/en/Reference/AttachInterrupt>`_ will -work as they should. - - +.. _arduino-delay-seealso: See also -------- -- `millis <http://arduino.cc/en/Reference/Millis>`_\ () -- `micros <http://arduino.cc/en/Reference/Micros>`_\ () -- `delayMicroseconds <http://arduino.cc/en/Reference/DelayMicroseconds>`_\ () -- `Blink Without Delay <http://arduino.cc/en/Tutorial/BlinkWithoutDelay>`_ - example - +- :ref:`millis() <arduino-millis>` +- :ref:`micros() <arduino-micros>` +- :ref:`delayMicroseconds() <arduino-delayMicroseconds>` +- (Arduino) `Blink Without Delay <http://arduino.cc/en/Tutorial/BlinkWithoutDelay>`_ example (works unmodified on Maple) |