Describe the difference between an interrupt and a polling in an embedded system.

Interrupt vs Polling in Embedded Systems

Interrupt and polling are two fundamental concepts in embedded systems that handle the interactions between the processor and external devices. Understanding the difference between them is crucial for designing efficient and responsive embedded systems.

Interrupt:

In an interrupt-driven system, external devices can send signals or requests to the processor to halt its current operation and handle the incoming event immediately. When an interrupt occurs, the processor stops its current task, saves its state, and jumps to the interrupt service routine (ISR) to address the interrupt. This allows for real-time responses to critical events and efficient utilization of processor resources.

Polling:

On the other hand, polling involves the processor regularly checking the status of external devices to see if they require attention. Instead of waiting for external events to trigger interrupts, the processor continuously polls the devices to determine if any action is needed. While polling is simpler to implement, it can be less efficient as it consumes processor resources even when no external events are present.

Key Differences:

• Interrupts provide real-time responsiveness to external events, while polling may introduce delays depending on the polling frequency.
• Interrupts consume fewer processor resources as they only trigger when needed, whereas polling can waste resources on continuous checks.
• Interrupts are more suitable for time-critical tasks, while polling may be sufficient for low-priority or non-real-time applications.

In conclusion, the choice between interrupt and polling in embedded systems depends on the specific requirements of the application, including real-time constraints, system responsiveness, and resource utilization.