Datasheet

Figure 20-12. Periodic Event with Beat Peripheral Triggers

Event

Peripheral Trigger

PENDCHn

Data Transfer

Trigger Lost

Block Transfer

BEAT

Conditional Transfer

The event input is used to trigger a conditional transfer on peripherals with pending transfer requests. For

example, this type of event can be used for peripheral-to-peripheral transfers, where one peripheral is the

source of event and the second peripheral is the source of the trigger.

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 (CHSTATUS.PEND), the respective Pending

Channel n Bit in the Pending Channels register is set (20.8.13 PENDCH.PENDCHn), and the event is

acknowledged. A software trigger will now trigger a transfer.

The figure below shows an example where conditional event is enabled with peripheral beat trigger

requests.

Figure 20-13. Conditional Event with Beat Peripheral Triggers

Event

Peripheral Trigger

PENDCHn

Data Transfer

Block Transfer

BEAT

Conditional Block Transfer

The event input is used to trigger a conditional block transfer on peripherals.

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.

The figure below shows an example where conditional event block transfer is started with peripheral beat

trigger requests.

SAM D21 Family

DMAC – Direct Memory Access Controller

Datasheet Complete

DS40001882D-page 318