How do you choose between polling and interrupt-driven input/output in embedded software?

Polling is a classical approach in control process. In general classical control process works like this: 1. Poll for changes(I/O states) 2. Calculate 3. Set outputs In this simple schema work for example PLCs. Polling consumes CPU cycles and should be planned well. In case of I/O you can for example poll state of whole port not only one input. If computing process is longer or irregular the better approach would be interrupt/event driven approaches.

?? Have you ever wondered what polling I/O is? It's simply a technique of checking a device or data source's status consistently, waiting to perform an action when specific conditions are met.?? ??Benefits: - ??Polling I/O is easy to implement. - ??No need for fancy hardware or software. ??Downsides: - ??It can be inefficient, draining CPU cycles and power. - ??It can lead to latency and overlooked events. ??For instance, think about polling a sensor to read its measurement or a serial port to detect available data. ?? Remember, every method has its pros and cons. It's essential to choose what suits best for your unique scenario. ?? Keep learning and growing, and never stop exploring! ????

It depends on the specific requirements of your application. Like Polling are easy to implement, suitable for low-priority operations. Mostly one should use it when the task is not that much time critical. opposite to which interrupt needs to be dealt on a immediate basis.

It's very important to understand what you can and can't do inside an ISR (interrupt service routine). Some low-level function calls are not safe to be called within an ISR and are usually documented as such. You should also keep your ISR execution time to a minimum. If time-consuming tasks need to be completed as a result of the interrupt those should be handled outside of the ISR. This is commonly achieved by setting a flag or adding an item to a queue in the ISR which is acted upon outside of the ISR function.

Interrupt-driven I/O is essential for IoT power efficiency, engaging the CPU only for critical events to extend battery life. While complex, with risks like priority inversion, employing nested interrupts and priority scheduling helps. The benefits—lower power use and improved responsiveness—are crucial. Modern tools (like Real-Time Operating Systems and Integrated Development Environments with advanced debugging features) simplify implementing these systems.

one should use interrupts for time-critical events, such as sensor readings or communication protocols, interrupt-driven I/O is essential to ensure timely responses.

Here are few pointers based on which we can identify which design to go with. 1. Hardware complexity : polling is simple and less complex. Interrupt is bit complex w.r.t hardware & process management. 2. Responsiveness (Accuracy) : Polling is low speed operation due to event checking at random interval. There are chances that event might not get serve as soon as it arrives. Interrupt based method will take care of this and give faster response on any such event. 3. Processing power : Polling draws more power due to continuous checking the event occurrence. Interrupt based method will consume less power since processor will only execute the action once the interrupt is generated. 4. Nature of event : Sync. (Polling) or Async. (Interrupt)

Use Polling I/O When: ☆ The system has low-priority I/O tasks. ☆ Timing is not critical. ☆ Simplicity is preferred over efficiency. ☆ Power consumption is not a major concern. Use Interrupt-Driven I/O When: ☆ Real-time response is required. ☆ Efficient CPU usage is important. ☆ The system has multiple devices with varying priorities. ☆ Power efficiency is a concern, as the CPU can sleep until an interrupt occurs.

One important thing to remember when doing polling is the speed of your polling loop. The amount of time it takes to run will determine the frequency at which you can act on input events. You should profile this frequency when no events are coming in as well as when events are coming in. If it takes a long time for you to process an event your loop frequency will drop temporarily which will affect your ability to handle subsequent events. Knowing your exact limitations here is crucial when using the polling approach.

Let's Rely on this: ?? Event Frequency & Urgency: ?? Polling works best for events that are infrequent, predictable, and not time-sensitive. On the other hand, use interrupts for frequent, random, or urgent events. ?? CPU Resources and Power: ? If your CPU has enough cycles and power to spare, polling can be a good choice. Want to save CPU cycles and power? Interrupts can help with that. ?? System Reliability & Robustness: ??? For operations where time is of the essence, interrupts are usually more reliable. ?? Software Design Flexibility: ?? Polling is simpler for uncomplicated tasks. But for complex systems with multiple tasks, interrupts get the job done. Hope that helps! ????

Assign appropriate priorities to interrupts to ensure that critical events are handled promptly. If your application can handle asynchronous events, interrupt-driven I/O might be a better choice. However, if your design is more synchronous, polling might be easier to implement.

Wondering how to effectively test and debug I/O? Check out these simple yet effective steps! ?? ?? Simulation Software: This tool helps you model device behavior, ensuring proper timing and functionality. ?? Oscilloscopes/Logic Analyzers: These come handy for monitoring signals from the devices. ?? Software Tools: They're used to inspect and modify the software state using methods like breakpoints, watchpoints, and tracepoints. ?? Logging and Reporting: It helps track data and events, making it easier to identify potential issues. Remember, the goal is to simplify the process. Choose tools that best suit your needs and always aim for clear, concise results. Happy debugging!

There are different pros and cons to choose Polling mechanism or interrupt driven mechanism. 1. If User just needs to use simple mechanism to check and execute into continuous method, then polling would be best if he/she doesn't have any concern regarding CPU cycle execution perspective. 2. User should use Interrupt driven mechanism when there is critical condition and immediate action should be taken with consideration of parallel work execution of other tasks or threads. 3. Most of Users are using Polling mechanism for bare metal programming where overall firmware is executed into single and sequential manner while interrupt driven mechanism will be used when system is complex and multiple tasks are running or waiting for resources.