Table 95. Masking Functionality; Figure 56. Direct Event Trigger Logic Cpu Wake-Up - STMicroelectronics STM32WL5 Series Reference Manual

Extended interrupts and event controller (EXTI)
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.
16.4.2 EXTI direct event input wake-up
The extended interrupt/event block diagram for direct events is shown in
direct events allow the wake-up 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 wake-up event. The
peripheral synchronous interrupt associated with the direct wake-up 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.
AHB
interface
hclk
hclk
Asynchronous
Direct event
rising edge
input(x)
detect circuit
rst
EXTI
Logic duplicated for each CPU
16.5 EXTI functional behavior
The direct event inputs are enabled in the respective peripheral generating the wake-up
event. The configurable events are enabled by enabling at least one of the trigger edges.
Once an event input is enabled, the generation of a CPU wake-up is conditioned by the
CPU interrupt mask and the CPU event mask.
CPU interrupt enable
EXTI_CnIMRm.IMb
0
512/1450

Figure 56. Direct event trigger logic CPU wake-up

Peripheral interface
CPUn CPUn
interrupt event
mask register mask register
Falling edge
detect pulse
generator
hclk
1) Only for the input events supporting the CPUn rxrev generation cn_event.

Table 95. Masking functionality

CPU event enable
EXTI_CnEMRm.EMb
0
1
Same circuit for configurable
and direct events
(1)
CPUn event(x)
Rising edge
CPUn
other events(x,y)
CPUn wakeup(x)
CPUn other wakeups
Other wakeups
Wakeup(x)
Configurable
event inputs it_exti_per(y)
EXTI_PRm.PIFb
No
No
RM0453 Rev 5
Figure 56.
EVG
hclk
cn_evt_rst
rising edge
detect cn_evt_exti
detect pulse
rst
hclk
cn_wakeup
sys_wakeup
(1)
CPUn event
Masked Masked
Masked Yes
RM0453
The
ck_fclk_cn
CPUn
cn_event
generator
MSv60762V1
CPUn
wake-up
Masked
Yes