Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet

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Atmel | SMART SAM D21 [DATASHEET]

Atmel-42181C–SAM-D21_Datasheet–07/2014

Conditional transfer: When the conditional transfer event action is selected, the event input is used to trigger a 
conditional transfer on peripherals with pending transfer requests. As example, this type of event can be used for 
peripheral to peripheral transfers, where one peripheral is source of event and the second peripheral is source of DMA 
trigger.

The peripheral Trigger Source must be set in Channel Control B register (

.TRIGSRC). Each peripheral trigger 

is stored internally when the event is received. When the peripheral trigger is stored internally, the Channel Pending 
status bit is set (

.PEND) and the event is acknowledged. A software trigger will now trigger a transfer.

 

 shows an example where conditional event is enabled with peripheral beat trigger requests.

Conditional block transfer: When the conditional block event action is selected, the event input is used to trigger a 
conditional block transfer on peripherals. The peripheral Trigger Source must be set in Channel Control B register 
(

.TRIGSRC).

Before starting transfers within a block, an event must be received. When received, the event is acknowledged when the 
block transfer is completed. A software trigger will trigger a transfer.

 shows an example where conditional event block transfer is enabled with peripheral beat trigger requests.

Trigger Lost

Trigger Lost

Peripheral Trigger

PENDCHn

Event

Block Transfer

Data Transfer

Event

Peripheral Trigger

PENDCHn

Data Transfer Block Transfer

Block Transfer

Block Transfer

Data Transfer

Peripheral Trigger

Event

PENDCHn