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authorMarti Bolivar <mbolivar@mit.edu>2010-11-28 11:23:33 -0500
committerMarti Bolivar <mbolivar@mit.edu>2010-11-28 11:23:33 -0500
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reorganized all the arduino/ docs into a lang/ subdirectory since
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-.. highlight:: cpp
-
-.. _arduino-attachinterrupt:
-
-attachInterrupt()
-=================
-
-Used to specify a function to call when an external interrupt (like an
-GPIO changing from LOW to HIGH, a button getting pressed, etc.)
-occurs.
-
-.. contents:: Contents
- :local:
-
-Library Documentation
----------------------
-
-.. doxygenfunction:: attachInterrupt
-
-.. doxygenenum:: ExtIntTriggerMode
-
-.. doxygentypedef:: voidFuncPtr
-
-Discussion
-----------
-
-Because the function will run in interrupt context, inside of it,
-:ref:`arduino-delay` won't work, and the value returned by
-:ref:`arduino-millis` will not increment. Serial data received while
-in the function may be lost. You should declare as ``volatile`` any
-global variables that you modify within the attached function.
-
-There are a few constraints you should be aware of if you're using
-more than one interrupt at a time; the :ref:`external-interrupts` page
-has the details.
-
-
-Using Interrupts
-----------------
-
-Interrupts are useful for making things happen automatically in
-microcontroller programs, and can help solve timing problems. A
-good task for using an interrupt might be reading a rotary encoder,
-or monitoring user input.
-
-
-If you wanted to insure that a program always caught the pulses
-from a rotary encoder, never missing a pulse, it would make it very
-tricky to write a program to do anything else, because the program
-would need to constantly poll the sensor lines for the encoder, in
-order to catch pulses when they occurred. Other sensors have a
-similar interface dynamic too, such as trying to read a sound
-sensor that is trying to catch a click, or an infrared slot sensor
-(photo-interrupter) trying to catch a coin drop. In all of these
-situations, using an interrupt can free the microcontroller to get
-some other work done while not missing the doorbell.
-
-
-Example
--------
-
-::
-
- int maple_led_pin = 13;
- volatile int state = LOW; // must declare volatile, since it's
- // modified within the blink handler
-
- void setup() {
- pinMode(maple_led_pin, OUTPUT);
- attachInterrupt(0, blink, CHANGE);
- }
-
- void loop() {
- digitalWrite(maple_led_pin, state);
- }
-
- void blink() {
- state = !state;
- }
-
-
-Arduino Compatibility
----------------------
-
-Most Arduino boards have two external interrupts: numbers 0 (on
-digital pin 2) and 1 (on digital pin 3). The Arduino Mega has an
-additional four: numbers 2 (pin 21), 3 (pin 20), 4 (pin 19), and 5
-(pin 18). On the Maple, you don't have to remember which interrupt
-number goes with which pin -- just tell ``attachInterrupt()`` the pin
-you want.
-
-
-See also
---------
-
-
-- :ref:`detachInterrupt <arduino-detachinterrupt>`
-- :ref:`external-interrupts`
-
-
-
-.. include:: cc-attribution.txt \ No newline at end of file