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ctimerstm32real-time-clock

STM32L1x Stop mode + RTC too much current

I am able to put my stm32L1xDiscovery board in STOP mode with RTC running. according to the datasheet this should draw about 1.3 µA. But my application draws 3.3 µA.

I noticed I did not put the FLASH in a low power mode during sleep. But when I did this, nothing changed.

This is what I use to go into STOP mode:

SCB->SCR |= ((uint32_t)SCB_SCR_SLEEPDEEP);

RCC->APB1ENR |= RCC_APB1Periph_PWR;
PWR->CR |= ((uint32_t)(PWR_CR_LPSDSR|PWR_CR_ULP)); // ULP seems to have no effect on power consumption
RCC->APB1ENR &= ~RCC_APB1Periph_PWR;

FLASH->ACR |= SLEEP_PD; // seems to have no effect at all on power consumption

__WFI();

Any idea what I am missing here?

Solution

  • If you use discovery board your measurement may be not clear because a lot of other components consumpt some energy. It's may be protection diode, driver of 3.3V line or second MCU with ST-LINK/V2 embedded debug tool.