Functional overview
STM32F031x4 STM32F031x6
14/113
DocID025743 Rev 3
In Standby mode, it is put in power down mode. In this mode, the regulator output is in high
impedance and the kernel circuitry is powered down, inducing zero consumption (but the
contents of the registers and SRAM are lost).
3.5.4 Low-power
modes
The STM32F031x4/x6 microcontrollers support three low-power modes to achieve the best
compromise between low power consumption, short startup time and available wakeup
sources:
Sleep
mode
In Sleep mode, only the CPU is stopped. All peripherals continue to operate and can
wake up the CPU when an interrupt/event occurs.
Stop
mode
Stop mode achieves very low power consumption while retaining the content of SRAM
and registers. All clocks in the 1.8 V domain are stopped, the PLL, the HSI RC and the
HSE crystal oscillators are disabled. The voltage regulator can also be put either in
normal or in low power mode.
The device can be woken up from Stop mode by any of the EXTI lines. The EXTI line
source can be one of the 16 external lines, the PVD output, RTC, I2C1 or USART1.
The peripherals listed above can be configured to enable the HSI RC oscillator for
processing incoming data. If this is used when the voltage regulator is put in low power
mode, the regulator is first switched to normal mode before the clock is provided to the
given peripheral.
Standby
mode
The Standby mode is used to achieve the lowest power consumption. The internal
voltage regulator is switched off so that the entire 1.8 V domain is powered off. The
PLL, the HSI RC and the HSE crystal oscillators are also switched off. After entering
Standby mode, SRAM and register contents are lost except for registers in the RTC
domain and Standby circuitry.
The device exits Standby mode when an external reset (NRST pin), an IWDG reset, a
rising edge on the WKUP pins, or an RTC event occurs.
Note:
The RTC, the IWDG, and the corresponding clock sources are not stopped by entering Stop
or Standby mode.
3.6
Clocks and startup
System clock selection is performed on startup, however the internal RC 8 MHz oscillator is
selected as default CPU clock on reset. An external 4-32 MHz clock can be selected, in
which case it is monitored for failure. If failure is detected, the system automatically switches
back to the internal RC oscillator. A software interrupt is generated if enabled. Similarly, full
interrupt management of the PLL clock entry is available when necessary (for example on
failure of an indirectly used external crystal, resonator or oscillator).
Several prescalers allow the application to configure the frequency of the AHB and the APB
domains. The maximum frequency of the AHB and the APB domains is 48 MHz.
微可Vicor——值得信赖的元器件供应商
http://www.vicor.top/
021-31660491
微可Vicor——值得信赖的元器件供应商
http://www.vicor.top/
021-31660491
