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How to choose best TICK_RATE_HZ?

Posted by Willem on February 17, 2009
Hi all (again),

In the documentation, it is stated that the default (1000hz) tick is higher than normally would be required.

What I notice is, that when i increase the tick count to 1050hz I never get a tick count.
This happens only when there is a task available. When I just start the scheduler, i can get as high as 10.000
without any problem. I get the tick count by using a trace macro on the PIC32.
What is this about? The task that is running is the only task and has nothing in it (except a continuous loop).

But my main question is, what is the best (highest) tick count without (crashing) sooner or later the tick count?

RE: How to choose best TICK_RATE_HZ?

Posted by Willem on February 17, 2009
Sorry, had to add this text too.

And when I select a tick rate off 100, the task will run continuously. (Also measured using trace functions)

This is the tasks only function:

vTaskDelay(5 / portTICK_RATE_MS );


RE: How to choose best TICK_RATE_HZ?

Posted by Dave on February 17, 2009
portTICK_RATE_MS will be less than 0 if configTICK_RATE_HZ is greater than 1000. As its an integer it will probably be a divide by zero.

RE: How to choose best TICK_RATE_HZ?

Posted by Willem on February 17, 2009
I just found out so :)

Thank you very much!

RE: How to choose best TICK_RATE_HZ?

Posted by Raphael Derosso Pereira on February 17, 2009
If you want, use the following macro for a generic greater than 1000 ticks converter:

#define rtos_convert_to_ms(A) (((A * 1000)/(1000000 / configTICK_RATE_HZ)))

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