PM0215 datasheet(30/91 Pages) STMICROELECTRONICS

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The STM32 Cortex-M0 processor

PM0215

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Doc ID 022979 Rev 1

Wakeup from WFE

The processor wakes up if:

●

it detects an exception with sufficient priority to cause exception entry

●

it detects an external event signal, see Section 2.5.3: The external event input

In addition, if the SEVONPEND bit in the SCR is set to 1, any new pending interrupt triggers

an event and wakes up the processor, even if the interrupt is disabled or has insufficient

priority to cause exception entry. For more information about the SCR see System control

2.5.3

The external event input

The processor provides an external event input signal. This signal can be generated by up

to 16 external input lines and other internal asynchronous events, configured through the

extended interrupt and event controller (EXTI).

This signal can wakeup the processor from WFE, or set the internal WFE event register to

one to indicate that the processor must not enter sleep mode on a later WFE instruction, see

Wait for event on page 29. Fore more details please refer to the STM32 reference manual,

section 4.3 Low power modes.

2.5.4

Power management programming hints

ISO/IEC C cannot directly generate the WFI, WFE or SEV instructions. The CMSIS provides

the following functions for these instructions:

void __WFE(void) // Wait for Event

void __WFI(void) // Wait for Interrupt

void __SEV(void) // Send Event

PM0215 Datenblatt(PDF) 30 Page - STMicroelectronics