Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
41
/
631
RCC, SPI1/2, UART4/5, USART2/3, I2C1/2 and WWDG register retention. The RET domain and the low-power
power domain are still functioning normally.
SRAM1/2 can be configured to be retained in STOP2 mode via PWR_CTRL3.RAM1RET and
PWR_CTRL3.RAM2RET. All I/O pins except PC13/14/15 are in retention state by default, PC13/14/15 can be
configured to retention the same state as run mode.
Enter STOP2 mode
To enter STOP2 mode, should be configured: SCB_SCR.SLEEPDEEP = 1, PWR_CTRL1.LPMSEL = "000~010".
In STOP2 mode, if FLASH is being operated, the time to enter STOP2 mode will be delayed until the memory access
is completed.
If the access to the APB area is in progress, the time to enter the STOP2 mode will be delayed until the APB access
is completed.
In STOP2 mode, the following peripherals are available:
Independent Watchdog (IWDG) optional: Once enabled, it will keep counting until a reset is generated.
RTC optional: It can be turned on by RCC_LDCTRL.RTCEN.
Internal RC oscillator (LSI RC) optional: It can be turned on by RCC_CTRLSTS.LSIEN.
External 32.768kHz crystal oscillator (LSE OSC) optional: It can be turned on by RCC_LDCTRL.LSEEN bit.
Other peripherals that can choose to hold or work such as GPIO, COMP, EXTI, LPUART, LPTIMER.
IO can be configured to retention or high-Z state.
Unneeded analog peripherals such as ADC and DAC can be disabled when entering STOP2 mode to avoid
unnecessary power consumption.
Exit STOP2 mode
When the STOP2 mode is exited by an interrupt or a wake-up event via the EXTI line, the system clock will be
restored to its previous state, and the code execution will continue from where it left off. System reset (NRST, IWDG)
can also exit STOP2 mode.
Note: When a system reset occurs, the CPU will run from address 0.
STANDBY mode
STANDBY mode is a Cortex®-M4 based Deep-Sleep mode. The core domain is completely turned off, the PLL, HSI,
HSE are turned off, and the LSI and LSE are optionally run. SRAM2 optional retention, RTC and IWDG optional
work. All GPIO pin states are selectable as retention or high-Z.
Note: The GPIO pin state will change to the system default state upon exit.
Enter STANDBY mode
Enter STANDBY mode by executing WFI/WFE and setting SCB_SCR.SLEEPDEEP = 1 and
PWR_CTRL1.LPMSEL = "011".