17 Demystifying Arduino Interrupts

The provided text explains the fundamental concept and practical implementation of interrupts in Arduino programming to achieve efficient multitasking. It illustrates that interrupts allow a microcontroller to immediately pause its current task to handle a high-priority event, such as a button press or sensor trigger, before returning to its original process. Through a comparison of traditional polling methods and interrupt-driven code, the source demonstrates how the latter solves issues with real-time responsiveness caused by delays in standard code loops. The tutorial outlines the specific syntax required for the attachInterrupt function, including parameters for the interrupt service routine (ISR) and various activation modes like "change" or "falling." Ultimately, the source highlights that mastering these signals is essential for developing advanced embedded systems that require precise, instantaneous reactions.

How do interrupts enhance responsiveness compared to traditional polling methods in embedded systems?

What specific parameters are required to configure an interrupt function within Arduino software?

Why are interrupt service routines essential for achieving effective multitasking in microcontroller programming?

Based on the sources provided, an Interrupt is a critical and interesting concept in embedded systems that allows a microcontroller like Arduino to handle multitasking and real-time tasks efficiently.

What is an Interrupt?

In Arduino programming, an interrupt occurs when the controller is busy executing a specific function (such as blinking an LED) but is forced to stop and execute a different function immediately due to an external signal. This signal can come from a digital pin, often triggered by a push button or a digital sensor.

Why Use Interrupts Instead of Traditional Methods?

In traditional programming, you might use digitalRead inside the void loop() to check the state of a button. However, if your code contains a delay (e.g., delay(1000)), the Arduino cannot check the button state until the delay period is over.

This results in a lack of "real-time" response, where the LED might not turn on immediately when the button is pressed.

Interrupts solve this by allowing the Arduino to act in real-time, executing the required action the moment the button is pressed, regardless of any delays in the main code.

Implementation Syntax

To use an interrupt, you must include the following line within the void setup() function:

attach Interrupt (digital Pin To Interrupt (pin), ISR, mode);

The parameters are defined as follows:

• Pin: The digital pin connected to the interrupt source (e.g., digital pin 2 or 3).

• ISR (Interrupt Service Routine): This is the name of the function you want the Arduino to call when the interrupt is generated.

• Mode: This defines the specific signal change that triggers the interrupt. There are four modes:
◦ LOW: Triggers whenever the pin is low.
◦ CHANGE: Triggers whenever the pin changes from low to high or high to low.
◦ RISING: Triggers only when the pin goes from low to high.
◦ FALLING: Triggers only when the pin goes from high to low.

Practical Example Summary

In the demonstration provided by the sources, a yellow LED is programmed to blink every second using a standard delay. Simultaneously, a red LED is controlled via an interrupt on pin 2. Using the CHANGE mode, the red LED reacts instantly to button presses in real-time, even while the yellow LED continues its timed blinking sequence.


--------------------------------------------------------------------------------
Analogy for Understanding: Think of working on a very important task at home. If someone knocks on your door, you must stop what you are doing immediately to address the person at the door before returning to your original task. The knock is the Interrupt, and answering the door is the Interrupt Service Routine (ISR).

Define the concept of an interrupt in embedded systems.

List the four available modes for the attachInterrupt function.

Explain the primary advantage of using interrupts over traditional polling.