RM0008 Interrupts and events
Doc ID 13902 Rev 12 199/1096
event request by writing a ‘1’ to the corresponding bit in the event mask register. When the
selected edge occurs on the event line, an event pulse is generated. The pending bit
corresponding to the event line is not set
An interrupt/event request can also be generated by software by writing a ‘1’ in the software
interrupt/event register.
Hardware interrupt selection
To configure the 20 lines as interrupt sources, use the following procedure:
● Configure the mask bits of the 20 Interrupt lines (EXTI_IMR)
● Configure the Trigger Selection bits of the Interrupt lines (EXTI_RTSR and
EXTI_FTSR)
● Configure the enable and mask bits that control the NVIC IRQ channel mapped to the
External Interrupt Controller (EXTI) so that an interrupt coming from one of the 20 lines
can be correctly acknowledged.
Hardware event selection
To configure the 20 lines as event sources, use the following procedure:
● Configure the mask bits of the 20 Event lines (EXTI_EMR)
● Configure the Trigger Selection bits of the Event lines (EXTI_RTSR and EXTI_FTSR)
Software interrupt/event selection
The 20 lines can be configured as software interrupt/event lines. The following is the
procedure to generate a software interrupt.
● Configure the mask bits of the 20 Interrupt/Event lines (EXTI_IMR, EXTI_EMR)
● Set the required bit of the software interrupt register (EXTI_SWIER)
10.2.5 External interrupt/event line mapping
The 112 GPIOs are connected to the 16 external interrupt/event lines in the following
manner:
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