Ontology-based Model For The Ward-round Process in Healthcare (OMWRP). "Ward-round", Healthcare

The timeout values equal 200ms, 300ms, and 500ms. The least common denominator is 100ms. If each hardware timer tick represents 10ms, then 100ms translates into a countdown value of 10. The ISR_timeout_fn keeps track of this countdown value and decrements it by one during each invocation. The ISR_timeout_fn notifies the worker task by a "give" operation on the worker task's semaphore after the countdown value reaches zero, effectively allowing the task to be scheduled for execution. The ISR_timeout_fn then reinitializes the countdown value back to 10. This concept is illustrated in Figure 11.4. In the ISR-to-processing-task model, the worker task must maintain an application-level, timer-countdown table based on 100ms granularity. In this example, the timer table has three countdown values: 2, 3, and 5 representing the 200ms, 300ms, and the 500ms application-requested timers. An application-installed, timer-expiration function is associated with each timer. This concept is illustrated in Figure 11.5. Figure 11.5: Servicing the timer interrupt in the task context ...»