Is using WFI with PIT-based scheduler safe in bare-metal on S32K311?

nowkoes 15 days ago

I am currently developing a bare-metal application using the S32K311 microcontroller, which is based on the ARM Cortex-M7 core. In our project, we are using the Periodic Interrupt Timer (PIT) to implement a cooperative scheduler that runs tasks every 10ms, 100ms, and 300ms.

for example)

function RunApplicationTasks():
    // 10ms period
    if timer_10ms_flag is TRUE:
        timer_10ms_flag = FALSE
        Execute10msTaskGroup()

    // 100ms period
    if timer_100ms_flag is TRUE:
        timer_100ms_flag = FALSE
        Execute100msTaskGroup()

    // 300ms period
    if timer_300ms_flag is TRUE:
        timer_300ms_flag = FALSE
        Execute300msTaskGroup()

While researching ways to reduce current consumption, I came across information about the WFI (Wait For Interrupt) instruction built into the Cortex-M7 core. Based on this, I am planning to structure my code as follows:

function RunApplicationTasks():
    // if all timer flag disable
    if (
        timer_10ms_flag is FALSE AND
        timer_100ms_flag is FALSE AND
        timer_300ms_flag is FALSE
    ):
        __asm volatile ("wfi");  // WFI

    // 10ms task
    if timer_10ms_flag is TRUE:
        timer_10ms_flag = FALSE
        Execute10msTaskGroup()

    // 100ms task
    if timer_100ms_flag is TRUE:
        timer_100ms_flag = FALSE
        Execute100msTaskGroup()

    // 300ms task
    if timer_300ms_flag is TRUE:
        timer_300ms_flag = FALSE
        Execute300msTaskGroup()

I’m posting this to ask whether this approach is safe and reliable in a bare-metal environment.