Table 83. Masking Functionality; Figure 42. Direct Event Trigger Logic Cpu Wakeup - STMicroelectronics STM32WLEx Reference Manual

RM0461
AHB
interface
hclk
hclk
Asynchronous
Direct event
rising edge
input(x)
detect circuit
rst
EXTI
1) Only for the input events supporting the CPU rxrev generation c_event.
14.5 EXTI functional behavior
The direct event inputs are enabled in the respective peripheral generating the wakeup
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 wakeup is conditioned by the CPU
interrupt mask and the CPU event mask.
CPU interrupt enable
EXTI_IMRm.IMb
0
1
1. Only if the CPU interrupt is enabled in EXTI_IMRm.IMb.
For configurable event inputs, when the enabled edges occur on the event input, an event
request is generated. When the associated it_exti_per(y) interrupt is unmasked, the
corresponding pending bit in EXTI_PR is set, the CPU sub-system wakes up and the CPU
interrupt signal is activated. The EXTI_PR pending bit must be set to 1 by software. This
clears the it_exti_per(y) interrupt.
For direct event inputs, when enabled in the associated peripheral, an event request is
generated on the rising edge only. There is no corresponding CPU pending bit in the EXTI.
When the associated direct event is unmasked in EXTI_IM, the CPU sub-system wakes up.
The CPU is woken up (interrupted) by the peripheral synchronous interrupt.

Figure 42. Direct event trigger logic CPU wakeup

Peripheral interface
CPU CPU
interrupt event
mask register mask register
Falling edge
detect pulse
generator
hclk

Table 83. Masking functionality

CPU event enable
EXTI_EMRm.EMb
0
1
0
1
Extended interrupts and event controller (EXTI)
Same circuit for configurable
and direct events
(1)
CPU event(x)
Rising edge
CPU
other events(x,y)
CPU wakeup(x)
CPU other wakeups
Other wakeups
Wakeup(x)
Configurable
event inputs it_exti_per(y)
EXTI_PRm.PIFb
No
No
Status latched
Status latched
RM0461 Rev 5
EVG
hclk
c_evt_rst
rising edge
c_evt_exti
detect
detect pulse
rst
hclk
c_wakeup
sys_wakeup
CPU event
Masked Masked
Masked Yes
Yes Masked
Yes Yes
ck_fclk_c
CPU
c_event
generator
MSv60763V1
CPU
wakeup
Masked
Yes
(1)
Yes
Yes
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