rtel wrote on Wednesday, June 22, 2016:
1.What is System_Tick() interrupt priority in FREE RTOS ?
Search for configKERNEL_INTERRUPT_PRIORITY on this page http://www.freertos.org/RTOS-Cortex-M3-M4.html and other pages on the website.
2.What is the range of Tasks priority in Free RTOS ?
3.What is the range of ISR priority in Free RTOS ?
That depends on the MCU as not all Cortex-M devices have the same priority ranges. See the link posted in answer to question 1 and the user manual for your STM32.
4.Can in use librery functions in ISR ( for example memset in ISR) ?
That depends on the library function. Juse when writing a bare metal application (with no OS) callilng memset() should be fine, but calling something like malloc() or printf() would be a very bad idea.