Trouble entering STOP2 on stm32l432

[Geoffrey1]

Posted on July 09, 2018 at 15:06

I'm having trouble entering stop2 -- instead of going to stop2 my code seems to enter sleep; this is based upon measuring power levels -- I have the RTC fed by an external crystal and a 1 second interval alarm.  I can clearly see the transitions from sleep to run and back.      I'm just doing the standard thing

MODIFY_REG(PWR->CR1,

PWR_CR1_LPMS, PWR_CR1_LPMS_STOP2);         SET_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));         __SEV();         __WFE();         __WFE();         CLEAR_BIT(SCB->SCR, ((uint32_t)SCB_SCR_SLEEPDEEP_Msk));

If instead I enter standby, the power levels drop to where I expect them (e.g. < 1uA), so I don't thing this power is leaking outside the stm32.   So something is either preventing entry to stop2 or just consuming power internal to the stm32.  This board is really simple -- just an adxl362 and a crystal.  In a different context (external RTC instead of crystal) I've had no problem entering STOP2.    I have read about the PWR_CR1_LPR bit, but I don't think that's the problem.   Any thoughts on ways to diagnose this ?

[Geoffrey1]

Posted on July 11, 2018 at 22:45

Case closed --  do the following before 'going down':

DBGMCU->CR = 0;

Not sure what is setting the flag to keep debug power on (openocd ?), but  this was what kept the power on.