rtel wrote on Saturday, January 20, 2018:
The SysTick timer is intended for use by an RTOS. It normally runs at the same frequency as the core. Set configCPU_CLOCK_HZ to the frequency the core will be executing at, then configTICK_RATE_HZ to the rate at which you want the RTOS tick interrupt to execute at, and the RTOS will setup the SysTick timer for you when the scheduler is started.
Typing on my phone so I can’t give you the links, but the config parameters are documented on the FreeRTOS.org website, where you will also find a free to download (if a little out of date) book.