What is an Interrupt?
An interrupt is an event that causes the microcontroller to pause its current task and execute a special set of instructions. It is triggered by an external event, such as a change in the state of a digital input pin, or a timer reaching a certain value. When an interrupt is triggered, the microcontroller stops what it is doing and jumps to the interrupt service routine (ISR).
How Does an Interrupt Work?
When an interrupt is triggered, the microcontroller stops what it is doing and jumps to the ISR. The ISR is a special set of instructions that are executed when the interrupt is triggered. The ISR can perform any number of tasks, such as reading a sensor, updating a display, or sending a signal to another device. After the ISR is finished, the microcontroller resumes its previous task.
Types of Interrupts
There are two types of interrupts: hardware interrupts and software interrupts. Hardware interrupts are triggered by an external event, such as a change in the state of a digital input pin. Software interrupts are triggered by a special instruction in the program code.
Advantages of Interrupts
Interrupts are useful because they allow the microcontroller to respond quickly to external events. Without interrupts, the microcontroller would have to continuously poll the sensors to check for changes. This is inefficient and can lead to missed events. Interrupts also allow the microcontroller to multitask, as it can respond to external events while performing other tasks.
Disadvantages of Interrupts
Interrupts can be difficult to debug because they can occur at any time. If an interrupt is triggered while the microcontroller is in the middle of executing a task, it can cause unexpected behavior. Additionally, interrupts can conflict with each other, resulting in unpredictable behavior.
External Interrupts
External interrupts are triggered by outside sources, like a button press or a signal from a sensor. These are the interrupts were more likely to use in Arduino projects. External interrupts can be configured to trigger on either a rising or falling edge of the signal. A rising edge is when the signal goes from low to high and a falling edge is when the signal goes from high to low.
Configuring External Interrupts
Configuring external interrupts is relatively straightforward. The Arduino has a few built-in functions that allow us to set up and use external interrupts. The first one is attachInterrupt(). This function takes three arguments. The first one is the interrupt number, which can be either 0 or 1. The second argument is the name of the function that will be called when the interrupt triggers. The third argument is the type of interrupt, which can be either LOW, CHANGE, RISING, or FALLING.
Using Interrupts in Arduino
Once an interrupt is configured, it can be used in an Arduino sketch. When an interrupt triggers, the Arduino will jump to the function specified in the attachInterrupt() function. This function should contain the code that will be executed when the interrupt triggers. After the code in the function is executed, the Arduino will return to the line of code that was being executed before the interrupt triggered.
Advantages of Interrupts
Using interrupts has several advantages over using polling or sequential program execution. Interrupts allow us to respond to events quickly and efficiently. They also allow us to prioritize certain events over others, which is important in safety-critical applications. Finally, interrupts allow us to respond to events that occur very quickly, like a button press, which would be impossible to detect using polling or sequential program execution.
Interrupts in Arduino 2
Interrupts are a powerful tool for controlling the flow of code execution in Arduino. They allow the microcontroller to respond to external events and can be triggered by a variety of sources, such as button presses, sound, light and other sensors. In Arduino Uno, two or three pins are connected to interrupts, but all pins are interrupt-capable.
Types of Interrupts
Interrupts can be divided into two main categories: internal and external. Internal interrupts are triggered by events within the microcontroller chip, such as timer overflow or a watchdog timer. External interrupts, on the other hand, are triggered by external sources, such as button presses or sensors.
Polling vs Interrupts
When dealing with sensors, there are two main ways to write code: polling and interrupts. Polling is the process of executing code line by line in the order it was written. This means that the microcontroller will check the sensor at a regular interval to see if it has been triggered. Interrupts, on the other hand, are more efficient and can be safer in many instances. When an interrupt is triggered, the microcontroller stops what it is doing to attend to a higher priority task.
Interrupts are a powerful tool for controlling the flow of code execution in Arduino. They allow the microcontroller to respond to external events and can be triggered by a variety of sources. Interrupts can be divided into two main categories: internal and external. Polling is the process of executing code line by line in the order it was written, while interrupts are more efficient and can be safer in many instances.