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STM32L071CB ISRPENDING from disabled SysTick?

MMici.1
Associate II

Dear All,

some context first:

 - STM32L071CB

 - Running RTOS (tickless mode)

   - SYS Mode - Timebase Source TIM2

   - RTOS timebase - LPTIM1

 - Execution paused by Breakpoint in a task with highest priority

   which is attempting to put the MCPU into STANDBY

In ICSR register I see ISRPENDING 1 and VECTPENDING 0x1F (31 dec)

According to PM0223 when subtracting 16 from VECTPENDING I get

the source of the exception/interrupt; 31 - 16 = 15 -> SysTick | Reserved

(Table 5). But PENDSTSET which should indicate SysTick exception

pending is zero meaning that there is no SysTick exception.

EXTI -> PR register indicates no pending interrupt (all '0').

NVIC -> NVIC_ICPR0 indicates pending interrupt from both TIM2

and LPTIM1.

Am I getting a SysTick exception even though the SysTick is

disabled or am I overlooking / not understanding something?

(We are investigating an issue where putting the MCPU into

 STANDBY intermittently fails - program continues after _WFI();)

Thank you

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