Dear, I use CORTEX M4 -(SAM4LC8) with FreeRtos Kernel, I would like to know how the switching of the tasks works. Is there any timer ? which timer? is it RTC?. Because on AVR I used the FreeRtos, where the tasks were switched by timer. I found function vPortSetupTimerInterrupt, but there is nothing like init of any timer, which could swith the tasks. Thanks in advance for help. Best Regards. Jan Ropek.

Assuming you are using a standard rather than tickless port (as there is a tickless implementation for the SAM4L) then it is using the SysTick timer, which is build into the Cortex-M core itself rather than being a separate peripheral. Regards.

OK, and does the SysTick timer tick in sleep mode? in datasheet is not any information about SysTick timer, there is only information about RCSYS – but suppose, that is different timer?! Regards.

OK, and does the SysTick timer tick in sleep mode?

That would depend on the sleep mode. http://www.freertos.org/low-power-tickless-rtos.html

in datasheet is not any information about SysTick timer,

You need to be looking in the ARM Cortex-M datasheet – there is a lot of information. Simply Googling “Cortex Systick timer” will overwhelm you with information.

there is only information about RCSYS – but suppose, that is different timer?!

Quite definitely a different timer. Presumably that is a peripheral timer that is specific to the device you are using, rather than part of the Cortex core. Regards.