16.3.2.4 Event Users

The event channel to listen to is selected by configuring the event user. An event user may require the event signal to be either synchronous or asynchronous to the peripheral clock. An asynchronous event user can respond to events in sleep modes when clocks are not running. Such events can be responded to outside the normal edges of the peripheral clock, making the event user respond faster than the clock frequency would suggest. For details on the requirements of each peripheral, refer to the documentation of the corresponding peripheral.

Most event users implement edge or level detection to trigger actions in the corresponding peripheral based on the incoming event signal. In both cases, a user can either be synchronous, which requires that the incoming event is generated from the peripheral clock (CLK_PER), or asynchronous, if not. Some asynchronous event users do not apply event input detection but use the event signal directly. The different event user properties are described in general in the table below.

Table 16-3. Properties of Event Users
Input Detection	Async/Sync	Description
Edge	Sync	An event user is triggered by an event edge and requires that the incoming event is generated from CLK_PER
Edge	Async	An event user is triggered by an event edge and has asynchronous detection or an internal synchronizer
Level	Sync	An event user is triggered by an event level and requires that the incoming event is generated from CLK_PER
Level	Async	An event user is triggered by an event level and has asynchronous detection or an internal synchronizer
No detection	Async	An event user will use the event signal directly

The table below shows the available event users for this device family.

Table 16-4. Event Users
USER Name		Description	Input Detection	Async/Sync
Peripheral	Input	Description	Input Detection	Async/Sync
CCL	LUTnx	LUTn event input x	Level	Async
ADCn	START	ADC start on event	Edge	Async
EVSYS	EVOUTx	EVSYS pin output x	No detection	Async
USARTn	IRDA	USARTn IrDA event input	Level	Sync
TCEn	CNTA	Count on positive event edge	Edge	Sync
		Count on any event edge	Edge
		Count while event signal is high	Level
		Event level controls count direction, up when low and down when high	Level
	CNTB	Event level controls count direction, up when low and down when high	Level	Sync
		Restart counter on positive event edge	Edge
		Restart counter on any event edge	Edge
		Restart counter while event signal is high	Level
TCBn	CAPT	Timeout check	Edge	Sync
		Input capture on event	Edge
		Input capture frequency measurement	Edge
		Input capture pulse-width measurement	Edge
		Input capture frequency and pulse-width measurement	Edge
		Single-shot	Edge	Both
	COUNT	Count on event	Edge	Sync
TCFn	COUNT	Count on event	Edge	Async
TCFn	ACTION	Event action	Edge/level	Async
WEXn	FAULTA	Fault input A	Level	Async
	FAULTB	Fault input B	Level	Async
	FAULTC	Fault input C	Level	Async