Three questions, with a bit of background.
Many of the functions that may be safely called from an ISR have a pointer parameter often named pxHigherPriorityTaskWoken. My understanding is that if this is not NULL, and the associated call causes a higher priority task to unblock, then *pxHigherPriorityTaskWoken will be set true, and the calling ISR should call portYIELDFROM
ISR() prior to returning to activate the unblocked, higher priority task.
- Is this a correct understanding?
- If portYIELDFROMISR isn’t called, then the task will eventually be unblocked, but not until some other event causes the scheduler to reevalute the ready tasks; is that correct?
Finally, I’ve noticed that the online API documentation (example: http://www.freertos.org/a00119.html) has changed to add this note to the pxHigherPriorityTaskWoken parameter:
“From FreeRTOS V7.3.0 pxHigherPriorityTaskWoken is an optional parameter and can be set to NULL.”
3. If you don’t supply this parameter, then you won’t be notified of a higher-priority task being woken, so it won’t get scheduled as soon as possible; is that the sole effect of not using this parameter?