Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
397
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
The EVSYS is reset by writing a one to the Software Reset bit in the Control register (CTRL.SWRST). All registers in the
EVSYS will be reset to their initial state and any ongoing events will be canceled. Refer to the
EVSYS will be reset to their initial state and any ongoing events will be canceled. Refer to the
register for details.
23.6.2.3 Channel Path
There are three different ways to propagate the event provided by an event generator:
z
Asynchronous path
z
Synchronous path
z
Resynchronized path
Figure 23-2. Channel
The path is selected by writing to the Path Selection bit group in the Channel register (CHANNEL.PATH).
Asynchronous Path
When using the asynchronous path, the events are propagated from the event generator to the event user with no
intervention from the event system. This means that if the GCLK_EVSYS_CHANNELx for the channel used is inactive,
the event will still be propagated to the user.
intervention from the event system. This means that if the GCLK_EVSYS_CHANNELx for the channel used is inactive,
the event will still be propagated to the user.
Events propagated in the asynchronous path cannot generate any interrupts, and no channel status bits will indicate the
state of the channel. No edge detection is available; this must be handled in the event user.
state of the channel. No edge detection is available; this must be handled in the event user.
When the event generator and the event user share the same generic clock, using the asynchronous path will propagate
the event with the least amount of latency.
the event with the least amount of latency.
Synchronous Path
Synchronous path can be used when the event generator and event user share the same generic clock generator and
also if event user supports synchronous path. If event user doesn't support synchronous path, asynchronous path has to
be selected. If they do not share the same generic clock generator, a logic change from the event generator to the event
channel might not be detected in the channel, which means that the event will not be propagated to the event user.
also if event user supports synchronous path. If event user doesn't support synchronous path, asynchronous path has to
be selected. If they do not share the same generic clock generator, a logic change from the event generator to the event
channel might not be detected in the channel, which means that the event will not be propagated to the event user.
When using the synchronous path, the channel is capable of generating interrupts. The channel status bits in the
Channel Status register (
Channel Status register (
) are also updated and available for use.
CHANNEL.SWEVT
CHANNEL m
CHANNEL.EVGEN
PERIPHERALS
SLEEPWALKING
DETECTOR
CLOCK_REQUEST_m
CHANNEL.PATH
RESYNC
EDGE
DETECTION
CHANNEL.EDGSEL
CHANNEL_EVT_m
GENERATORS EVENTS
SYNC
ASYNC