Interrupts

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Overview
Task
Queue
Timer
Interrupt Management

This library allows users to trigger a process interrupt function or enable/disable an interrupt function when the input to a pin changes value.

attachInterrupt

Description

Specifies a function to execute (call) when an external interrupt occurs (signal on external pin).

Syntax

attachInterrupt(pin, void(*)(void) func, mode)

Parameters

pin: The number of the interrupt number (One of 2, 6, 11, 12, 24)
func: The function to call when the interrupt occurs
mode:
LOW (to trigger the interrupt whenever the pin is low)
CHANGE (to trigger the interrupt whenever the pin changes value)
FALLING (to trigger when the pin goes from high to low)
RISING (to trigger when the pin goes from low to high)

Returns

None

detachInterrupt

Description

Turns off the interrupt specified in attachInterrupt.

Syntax

detatachInterrupt(pin)

Parameters

pin: The number of the pin used for the interrupt (One of 2, 6, 11, 12, 24)

Returns

None

interrupts

Description

Re-enables the interrupt disabled in noInterrupts.

Syntax

interrupts()

Parameters

None

Returns

None

noInterrupts

Description

Disables an interrupt process. Use this when you need to protect the timing of a specific process; this can even be used to disable an important task run in the background.

Syntax

noInterrupts()

Parameters

None

Returns

None

This is a sample that generates an interrupt when Pin 11 changes.

#include <Arduino.h>
int pin = PIN_LED1;
volatile int state = LOW;
void blink()
{
  state = !state;
}
 
void setup()
{
  pinMode(pin, OUTPUT);
  attachInterrupt(11, blink, CHANGE);
}
 
void loop()
{
  digitalWrite(pin, state);
}