Low-Power Modes; Figure 11. Pvd Thresholds - ST STM32F412 Reference Manual

Power controller (PWR)
PVD output
5.3

Low-power modes

By default, the microcontroller is in Run mode after a system or a power-on reset. In Run
mode the CPU is clocked by HCLK and the program code is executed. Several low-power
modes are available to save power when the CPU does not need to be kept running, for
example when waiting for an external event. It is up to the user to select the mode that gives
the best compromise between low-power consumption, short startup time and available
wakeup sources.
The devices feature four low-power modes:
• Sleep mode (Cortex
•
Stop mode (all clocks are stopped)
• Standby mode (1.2 V domain powered off)
•
Batch acquisition mode (BAM): the devices are in Sleep mode, the Flash memory is off,
needed peripheral are kept running, data transfer are still possible through DMA.
In addition, the power consumption in Run mode can be reduce by one of the following
means:
•
Slowing down the system clocks
•
Gating the clocks to the APBx and AHBx peripherals when they are unused.
Entering low-power mode
Low-power modes are entered by the MCU by executing the WFI (Wait For Interrupt), or
WFE (Wait for Event) instructions, or when the SLEEPONEXIT bit in the Cortex
FPU System Control register is set on Return from ISR.
Entering Low-power mode through WFI or WFE will be executed only if no interrupt is
pending or no event is pending.
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Figure 11. PVD thresholds

VDD
®
-M4 with FPU core stopped, peripherals kept running)
RM0402 Rev 6
PVD threshold
RM0402
100 mV
hysteresis
MS30432V2
®
-M4 with