Datasheet

Table Of Contents

When using synchronous or resynchronized path, the Event System includes options to transfer events to

users when rising, falling or both edges are detected on event generators.

For further details, refer to the Channel Path section of this chapter.

Related Links

31.5.2.6 Channel Path

31.5.2 Basic Operation

31.5.2.1 Initialization

Before enabling event routing within the system, the Event Users Multiplexer and Event Channels must

be selected in the Event System (EVSYS), and the two peripherals that generate and use the event have

to be configured. The recommended sequence is:

1. In the event generator peripheral, enable output of event by writing a '1' to the respective Event

Output Enable bit ("EO") in the peripheral's Event Control register (e.g., TCC.EVCTRL.MCEO1,

AC.EVCTRL.WINEO0, RTC.EVCTRL.OVFEO).

2. Configure the EVSYS:

2.1. Configure the Event User multiplexer by writing the respective EVSYS.USERm register,

see also 31.5.2.3 User Multiplexer Setup.

2.2. Configure the Event Channel by writing the respective EVSYS.CHANNELn register, see

also 31.5.2.4 Event System Channel.

3. Configure the action to be executed by the event user peripheral by writing to the Event Action bits

(EVACT) in the respective Event control register (e.g., TC.EVCTRL.EVACT,

PDEC.EVCTRL.EVACT). Note: not all peripherals require this step.

4. In the event user peripheral, enable event input by writing a '1' to the respective Event Input Enable

bit ("EI") in the peripheral's Event Control register (e.g., AC.EVCTRL.IVEI0,

ADC.EVCTRL.STARTEI).

31.5.2.2 Enabling, Disabling, and Resetting

The EVSYS is always enabled.

The EVSYS is reset by writing a ‘1’ to the Software Reset bit in the Control A register (CTRLA.SWRST).

All registers in the EVSYS will be reset to their initial state and all ongoing events will be canceled.

Refer to CTRLA.SWRST register for details.

31.5.2.3 User Multiplexer Setup

The user multiplexer defines the channel to be connected to which event user. Each user multiplexer is

dedicated to one event user. A user multiplexer receives all event channels output and must be

configured to select one of these channels, as shown in Block Diagram section. The channel is selected

with the Channel bit group in the User register (USERm.CHANNEL).

The user multiplexer must always be configured before the channel. A list of all user multiplexers is found

in the User (USERm) register description.