What is an interrupt and why is it used in microcontroller-based mechatronics systems?

• A. An interrupt is a signal that periodically restarts the main loop.
• B. An interrupt is a request from the operating system to schedule tasks.
• C. An interrupt is a signal that temporarily halts normal execution to run a high-priority task.
• D. An interrupt is a debug feature used only during development.

Answer: (C)

An interrupt is a signal that momentarily interrupts the current program to run a short, high-priority routine. In microcontroller mechatronics, events from sensors or peripherals can happen at any moment and may need immediate attention—for example a limit switch being pressed, a pulse from an encoder, or a communication event. Polling inputs in a loop can miss fast changes or waste time checking repeatedly, but interrupts let the CPU respond with low latency whenever the event occurs.

After the interrupt service routine finishes, the processor returns to what it was doing, resuming the main control flow with minimal disruption. This makes the system more responsive and predictable for time-critical tasks like precise motor control or safety interlocks.

Keep in mind that interrupts should be short and fast; heavy work belongs in the main loop. Share data between an ISR and the main program using volatile variables, and keep ISR-side operations minimal to avoid delaying other important tasks.