Datasheet

310
Atmel | SMART SAM D20 [DATASHEET]
Atmel-42129K–SAM-D20_datasheet–06/2014
To configure a channel, the Channel register must be written in a single 32-bit write.
It is possible to read out the configuration of a channel by first selecting the channel by writing to CHANNEL.CHANNEL
using a, 8-bit write, and then performing a read of the CHANNEL register.
Event Generators
The event generator is selected by writing to the Event Generator bit group in the Channel register (CHANNEL.EVGEN).
A full list of selectable generators can be found in the CHANNEL register description. Refer to Table 22-3 for details.
The channels are not connected to any of the event generators (CHANNEL.EVGEN = 0x00) by default.
22.6.2.5 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 22-3. 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_x 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.
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.
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