Figure 41. Configurable Event Trigger Logic Cpu Wakeup - STMicroelectronics STM32WLEx Reference Manual

Extended interrupts and event controller (EXTI)
AHB
Falling Rising
interface
trigger trigger
selection selection
hclk
register register
Configurable
Asynchronous edge
event
detection circuit
input(y)
rst
EXTI
1) Only for the input events supporting the CPU rxrev generation c_event.
The software interrupt event register allows configurable events to be triggered by software,
writing the corresponding register bit, irrespective of the edge selection setting.
The rising and falling edges selection registers allow the configurable event active trigger
edge (or both edges) to be enabled.
The CPU has its dedicated interrupt mask and event mask registers. The enabled event
allows the generation of an event on the CPU. All events for a CPU are ORed together into
a single CPU event signal. The event pending register (EXTI_PR) is not set for an
unmasked CPU event.
The configurable events have unique interrupt pending request registers, shared by the
CPU. The pending register is only set for an unmasked interrupt. Each configurable event
provides a common interrupt to the CPU. The configurable event interrupts need to be
acknowledged by software in the EXTI_PR register.
When a CPU interrupt or CPU event is enabled, the asynchronous edge detection circuit is
reset by the clocked delay and rising edge detect pulse generator. This guarantees that the
EXTI hclk clock is woken up before the asynchronous edge detection circuit is reset.
Note: A detected configurable event interrupt pending request may be cleared by the CPU. The
system is not able to enter into low-power modes as long as an interrupt pending request is
active.
14.4.2 EXTI direct event input wakeup
The extended interrupt/event block diagram for direct events is shown in
direct events allow the wakeup of the system and of the CPU from Sleep and Stop modes.
The direct events do not have an associated EXTI interrupt. The EXTI only wakes up the
system and CPU sub-system clocks and may generate a CPU wakeup event. The
peripheral synchronous interrupt associated with the direct wakeup event, wake up the
CPU. The EXTI direct event is able to generate a CPU event. This CPU event wakes up the
CPU.
The CPU event may occur before the associated peripheral interrupt flag is set.
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Figure 41. Configurable event trigger logic CPU wakeup

Peripheral interface
Software CPU
interrupt event
event mask
register register
hclk
Rising
edge
detect
pulse
generator
CPU
Pending
interrupt
request
mask
register
register
Same circuit for configurable
(1)
CPU event(y)
CPU
other events(x,y)
CPU
other wakeups
CPU
Other wakeups
wakeup(y)
RM0461 Rev 5
it_exti_per(y)
EVG
and direct events
hclk
c_evt_rst
Rising edge
detect c_evt_exti
rst
hclk
c_wakeup
sys_wakeup
Figure 42.
RM0461
ck_fclk_c
CPU rising
edge detect
c_event
pulse
generator
MSv60761V1
The