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Configure RTOS tick under 1ms versus portTICK_PERIOD_MS

Posted by simointe on June 13, 2016

(TMS570LC4, nested interrupt, C++, FreeRTOS V9.0.0rc2, compiler TI v5.2.7, rtos running ok).

Considering ~~~

define portTICKPERIODMS ((TickTypet) 1000 / configTICKRATE_HZ)

~~~ where tickTypet is unsigned long, it means that 1KHz is the maximum frequency I can setup the tick ? portTICKPERIOD_MS seems to be used in many places.

Configure RTOS tick under 1ms versus portTICK_PERIOD_MS

Posted by rtel on June 13, 2016

portTICKPERIODMS is not used ANYWHERE in the FreeRTOS source code, it is only provided as a convenience, and in fact, its use is not recommended now as the pdTICKSTOMS() macro should be used in its place.

FreeRTOS V9.0.0 (not the release candidate) allows pdMSTOTICKS() to be overridden, should the default implementation not give the accuracy required (it considers speed more).

portTICKPERIODMS and pdMSTOTICKS() is used in a lot of places in example code and external components, but again for convenience, and FreeRTOS has no dependency on it.

That all said - it is rarely a good idea to set the tick rate greater than 1KHz - 100Hz being typical.

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