Resynchronized Path
The resynchronized path are used when the event generator and the event channel do not share the
same generator for the generic clock. When the resynchronized path is used, resynchronization of the
event from the event generator is done in the channel. For details on generic clock generators, refer to
GCLK - Generic Clock Controller
.
When the resynchronized path is used, the channel is able to generate interrupts. The channel busy n
bits in the Channel Status register (CHSTATUS.CHBUSYn) are also updated and available for use.
Related Links
GCLK - Generic Clock Controller
on page 121
30.6.2.7. Edge Detection
When synchronous or resynchronized paths are used, edge detection must be enabled. The event
system can execute edge detection in three different ways:
•
Generate an event only on the rising edge
•
Generate an event only on the falling edge
•
Generate an event on rising and falling edges.
Edge detection is selected by writing to the Edge Selection bit group of the Channel register
(CHANNELn.EDGSEL).
30.6.2.8. Event Latency
An event from an event generator is propagated to an event user with different latency, depending on
event channel configuration.
•
Asynchronous Path: The maximum routing latency of an external event is related to the internal
signal routing and it is device dependent.
•
Synchronous Path: The maximum routing latency of an external event is one
GCLK_EVSYS_CHANNEL_n clock cycle.
•
Resynchronized Path: The maximum routing latency of an external event is three
GCLK_EVSYS_CHANNEL_n clock cycles.
The maximum propagation latency of a user event to the peripheral clock core domain is three peripheral
clock cycles.
The event generators, event channel and event user clocks ratio must be selected in relation with the
internal event latency constraints. Events propagation or event actions in peripherals may be lost if the
clock setup violates the internal latencies.
30.6.2.9. The Overrun Channel n Interrupt
The Overrun Channel n interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.OVRn) will
be set, and the optional interrupt will be generated in the following cases:
•
One or more event users on channel n is not ready when there is a new event.
•
An event occurs when the previous event on channel m has not been handled by all event users
connected to that channel.
The flag will only be set when using synchronous or resynchronized paths. In the case of asynchronous
path, the INTFLAG.OVRn is always read as zero.
30.6.2.10. The Event Detected Channel n Interrupt
The Event Detected Channel n interrupt flag in the Interrupt Flag Status and Clear register
(INTFLAG.EVDn) is set when an event coming from the event generator configured on channel n is
detected.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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