Extended interrupt and event controller (EXTI) RM0367
292/1043 RM0367 Rev 7
13 Extended interrupt and event controller (EXTI)
13.1 Introduction
The extended interrupts and events controller (EXTI) manages the external and internal
asynchronous events/interrupts and generates the event request to the CPU/interrupt
controller plus a wake-up request to the power controller.
The EXTI allows the management of up to 30 event lines which can wake up the device
from Stop mode.
Some of the lines are configurable: in this case the active edge can be chosen
independently, and a status flag indicates the source of the interrupt. The configurable lines
are used by the I/Os external interrupts, and by few peripherals. Some of the lines are
direct: they are used by some peripherals to generate a wakeup from Stop event or
interrupt. In this case the status flag is provided by the peripheral.
Each line can be masked independently for interrupt or event generation.
Te EXTI controller also allows to emulate, by programming to a dedicated register, events or
interrupts by software multiplexed with the corresponding hardware event line.
13.2 EXTI main features
The EXTI main features are the following:
• Generation of up to 30 event/interrupt requests
– 22 configurable lines
– 7 direct lines
• Independent mask on each event/interrupt line
• Configurable rising or falling edge (configurable lines only)
• Dedicated status bit (configurable lines only)
• Emulation of event/interrupt requests (configurable lines only)
13.3 EXTI functional description
For the configurable interrupt lines, the interrupt line should be configured and enabled in
order to generate an interrupt. This is done by programming the two trigger registers with
the desired edge detection and by enabling the interrupt request by writing a ‘1’ to the
corresponding bit in the interrupt mask register. When the selected edge occurs on the
interrupt line, an interrupt request is generated. The pending bit corresponding to the
interrupt line is also set. This request is cleared by writing a ‘1’ in the pending register.
For the direct interrupt lines: the interrupt is enabled by default in the interrupt mask register
and there is no corresponding pending bit in the pending register.
To generate an event, the event line should be configured and enabled. This is done by
programming the two trigger registers with the desired edge detection and by enabling the
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.
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