Question

xercises 9.1 If you are using SysTick interrupts, how do you set the priority to level 6?

Answer 1

NVIC_SetPriority(SysTick_IRQn, 6);//set systick interrupt priority

If the parameter for priority is 0 for the function above(that’s also what I had in the function), 0 is 0x00 in hex and 0000 in binary, since the default priority grouping for stm32 is group 2, which is 2 bits for preemption priority and 2 bits for sub priority, we get 00 for preemption and 00 for sub. If we change the input from 0 to 7 for the function, the binary form for 7 is 0111, so higher 2 bits is 01 which is 1 in decimal gives you preemption priority as 1, and the lower 2 bits is 11 which is 3 gives you sub priority as 3.