How does interrupt handling work?
Interrupt handling is a fundamental concept in embedded systems that enables efficient and responsive system behavior. An interrupt is a signal sent to the processor by hardware or software indicating an event that requires immediate attention. When an interrupt occurs, the processor suspends its current execution (called the main program) and transfers control to a specific function known as an Interrupt Service Routine (ISR).
The ISR is a small, quick routine that deals with the event that triggered the interrupt. Once the ISR finishes execution, the processor resumes the previously suspended program from where it left off. This mechanism allows the system to respond to critical events—such as receiving data from a sensor or a user pressing a button—without the need to continuously check for these events (a process known as polling).
There are two main types of interrupts: hardware interrupts, which are triggered by external devices (like timers, I/O ports, etc.), and software interrupts, which are triggered by software instructions. Prioritization is another crucial part of interrupt handling—when multiple interrupts occur, the system must decide which one to handle first based on its priority level.
To manage interrupts efficiently, microcontrollers use interrupt vector tables, which map specific interrupt sources to their corresponding ISR addresses. Developers must also ensure ISRs are short and efficient to prevent the system from becoming unresponsive, especially in real-time applications.
Proper interrupt handling enhances system performance, reduces latency, and conserves processor power by avoiding constant polling. It’s a critical skill for embedded system developers, especially those working on real-time or safety-critical applications like automotive controls or medical devices.
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