time measure

malacay wrote on Friday, January 27, 2012:


efm32g290f128, arm3, IAR

I have a task priority 2 and priority tasks of these two creates the first
Now I will measure the time how long the two tasks need.
I’m thinking of the SysTick timer. He gives an interrupt every ms.
Am I on the wrong track? Is there something better?

davedoors wrote on Friday, January 27, 2012:

Your question is not clear, but here are some general comments on measuring time.

You can get the tick count by calling xTaskGetTickCount(). This will increment at the tick frequency, so give an accuracy of roughly twice the tick frequency. If that is good enough, use that.

If you want a higher resolution time value then use a hardware peripheral timer, and read its count value directly.

Hope that helps.

malacay wrote on Friday, January 27, 2012:

Ok, Thank you

I need a time reference, and I would like to build on a hardware peripheral timer.

The timer should be started by the task with priority 2.
If the task with Priorität2, the other tasks created with Priority 1 -> suspend
if the tasks is finished with Priority 1 -> Task Priority 2 resume
Now I want to measure the time for this part
How can I implement this?

rtel wrote on Friday, January 27, 2012:

If I understand you correctly, then you have the following scenario, where P1 is a task with priority 1, and P2 is a task with priority 2.

1: P2 suspends itself.
2: Because P2 is suspended P1 runs.
3: When P1 has done something it un-suspends (resumes) P2, so P2 runs again.

and you want to measure between step 1 and step 2.

If the tick count has enough resolution then you can do that by:

void P2( void *pvParameters )
xTickType xTimeBefore, xTotalTimeSuspended;
____for( ;; )
________/* Take a time before suspending. */
________xTimeBefore = xTaskGetTickCount();
________/* Suspend the task. */
________vTaskSuspend( NULL );
________/* The other task will have run an unsuspended P2 for this line to execute. */
________xTotalTimeSuspended = xTaskGetTickCount() - xTimeBefore;


malacay wrote on Wednesday, February 01, 2012:

Yes this work, thank you.