diff options
author | Marti Bolivar <mbolivar@mit.edu> | 2010-12-03 20:18:00 -0500 |
---|---|---|
committer | Marti Bolivar <mbolivar@mit.edu> | 2010-12-03 20:18:00 -0500 |
commit | 5ceac644e90c929e77f05d357d1d35d45e673fac (patch) | |
tree | 18c76f6117942fa46391fbbd8bd24e2c759c4895 /docs/source/lang/attachinterrupt.rst | |
parent | e5b1e44a8ae8c593456f4b4734f05c9065f6f07b (diff) | |
download | librambutan-5ceac644e90c929e77f05d357d1d35d45e673fac.tar.gz librambutan-5ceac644e90c929e77f05d357d1d35d45e673fac.zip |
cleaning up previous commits.
note that addition of new files under docs/source/lang/api and
docs/source/lang/cpp which were just copies of files in
docs/source/lang/ imply that change history is lost to git.
Diffstat (limited to 'docs/source/lang/attachinterrupt.rst')
-rw-r--r-- | docs/source/lang/attachinterrupt.rst | 102 |
1 files changed, 0 insertions, 102 deletions
diff --git a/docs/source/lang/attachinterrupt.rst b/docs/source/lang/attachinterrupt.rst deleted file mode 100644 index 0b8907f..0000000 --- a/docs/source/lang/attachinterrupt.rst +++ /dev/null @@ -1,102 +0,0 @@ -.. highlight:: cpp - -.. _lang-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:`lang-delay` won't work, and the value returned by -:ref:`lang-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 <lang-detachinterrupt>` -- :ref:`external-interrupts` - - - -.. include:: cc-attribution.txt |