ATXMEGA256A3B_09 ATMEL [ATMEL Corporation], ATXMEGA256A3B_09 Datasheet - Page 15

• Manufacturer Part Number: ATXMEGA256A3B_09
• Description: 8/16-bit XMEGA A3B Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

8. DMAC - Direct Memory Access Controller
8.1
8.2
8116F–AVR–09/09
Features
Overview
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The XMEGA A3B has a Direct Memory Access (DMA) Controller to move data between memo-
ries and peripherals in the data space. The DMA controller uses the same data bus as the CPU
to transfer data.
It has 4 channels that can be configured independently. Each DMA channel can perform data
transfers in blocks of configurable size from 1 to 64K bytes. A repeat counter can be used to
repeat each block transfer for single transactions up to 16M bytes. Each DMA channel can be
configured to access the source and destination memory address with incrementing, decrement-
ing or static addressing. The addressing is independent for source and destination address.
When the transaction is complete the original source and destination address can automatically
be reloaded to be ready for the next transaction.
The DMAC can access all the peripherals through their I/O memory registers, and the DMA may
be used for automatic transfer of data to/from communication modules, as well as automatic
data retrieval from ADC conversions, data transfer to DAC conversions, or data transfer to or
from port pins. A wide range of transfer triggers are available from the peripherals, Event System
and software. Each DMA channel has different transfer triggers.
To allow for continuous transfers, two channels can be interlinked so that the second takes over
the transfer when the first is finished and vice versa.
The DMA controller can read from memory mapped EEPROM, but it cannot write to the
EEPROM or access the Flash.
Allows High-speed data transfer
4 Channels
From 1 byte and up to 16M bytes transfers in a single transaction
Multiple addressing modes for source and destination address
1, 2, 4, or 8 byte Burst Transfers
Programmable priority between channels
– From memory to peripheral
– From memory to memory
– From peripheral to memory
– From peripheral to peripheral
– Increment
– Decrement
– Static
XMEGA A3B
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