Task switch

nobody wrote on Thursday, May 04, 2006:


i use the RTOS 3.2.2 with an Atmel SAM7.
In code there are 3 tasks with the same priority and they can use the same hardware (for example SPI Interface ).
If a task want’s to use the hardware it checks a flag and use the the hardware (with setting and clearing of the flag)  or it waits until the flag is cleared.
This works fine without any problems. Depending on the hardware the waiting time can be very short and i don’t want to use vTaskDelay(1).

Is it better to use vTaskSwitchContext() instead or is it not recommended.

Thanks for the help.



nobody wrote on Thursday, May 04, 2006:

I think maybe you should use a semaphore instead of a flag to avoid race conditions.

Never call vTaskSwitchContext()!!!!!!  Use taskYIELD() instead.

You could raise the priority of the task that has the semaphore, then lower it again before it gives it back.  This would prevent the other tasks from having to poll the flag.