RM0444 Rev 5 321/1390
RM0444 Extended interrupt and event controller (EXTI)
335
Note: A detected configurable event interrupt pending request can be cleared by the CPU. The
system cannot enter low-power modes as long as an interrupt pending request is active.
13.3.2 EXTI direct event input wakeup
Figure 28 is a detailed representation of the logic associated with direct event inputs waking
up the system.
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 wakes 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 interrupt flag of the associated peripheral is set.
Figure 28. Direct event trigger logic CPU wakeup
13.3.3 EXTI mux
The EXTI mux allows selecting GPIOs as interrupts and wakeup. The GPIOs are connected
via 16 EXTI mux lines to the first 16 EXTI events as configurable event. The selection of
GPIO port as EXTI mux output is controlled through the EXTI external interrupt selection
register (EXTI_EXTICRx) register.
EVG
EXTI
Direct
Event
input(x)
Asynchronous
Rising Edge
detect circuit
Falling Edge
detect
Pulse
generator
rst
Delay
hclk
CPU
Rising Edge
detect Pulse
generator
hclk
ck_fclk_c
Peripheral interface
CPU
Event
mask
register
c_event
c_wakeup
sys_wakeup
Other CPU Wakeups
Other Wakeups
CPU Event(x)
(1)
CPU Wakeup(x)
Wakeup(x)
Synch
hclk
AHB interface
CPU
Interrupt
mask
register
c_evt_exti
hclk
Other CPU Events(x,y)
hclk
rst
c_evt_rst
Same circuit for Configurable
and Direct events
MS46536V1
Rising
Edge
detect
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