Chris O'Byrne - YAVRTOS
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Using mutexes
A mutex is used to ensure that only one task is using a shared resource at any one time.Example - sharing I/O pins
Given that microcontrollers only have a limited number of I/O pins, it is common for pins to be dual-purpose.
mutex_t pin_mutex; void task1(void *p) { ... // task 1 now needs to use the dual-purpose pins lock_on(&pin_mutex); // we now "own" the mutex, so we "own" the pins do_stuff_with_the_dual_purpose_pins(); // release the pins lock_off(&pin_mutex); ... } void task2(void *p) { ... // task 2 now needs to use the dual-purpose pins lock_on(&pin_mutex); // we now "own" the mutex, so we "own" the pins do_other_stuff_with_the_dual_purpose_pins(); // release the pins lock_off(&pin_mutex); ... }