RM0091 Interrupts and events
Doc ID 018940 Rev 1 159/742
11.2 Extended interrupts and events controller (EXTI)
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 and a wake-up request to the Power Manager.
The EXTI allows the management of up to 28 external/internal event line (21 external event
lines and 7 internal event lines).
The active edge of each external interrupt line can be chosen independently, whilst for
internal interrupt the active edge is always the rising one. An interrupt could be left pending:
in case of an external one, a status register is instantiated and indicates the source of the
interrupt; an event is always a simple pulse and it’s used for triggering the core Wake-up
(e.g. Cortex-M0 RXEV pin). For internal interrupts, the pending status is assured by the
generating IP, so no need for a specific flag. Each input line can be masked independently
for interrupt or event generation, in addition the internal lines are sampled only in STOP
mode. This controller allows also to emulate the (only) external events by software,
multiplexed with the corresponding hardware event line, by writing to a dedicated register.
11.2.1 Main features
The EXTI main features are the following:
● support generation of up to 28 event/interrupt requests;
● Independent configuration of each line as an external or an internal event requests;
● Independent mask on each event/interrupt line
● Automatic disable of internal lines when system is not in STOP mode
● Independent trigger for external event/interrupt line
● Dedicated status bit for external interrupt line;
● Emulation for all the external event requests.
11.2.2 Block diagram
The extended interrupt/event block diagram is shown in Figure 20.
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