Datasheet

263
SAM9263 [DATASHEET]
Atmel-6249N-ATARM-SAM9263-Datasheet_14-Mar-16
Figure 24-2. DMAC Transfer Hierarchy for Non-Memory Peripheral
Figure 24-3. DMAC Transfer Hierarchy for Memory
Block: A block of DMAC data. The amount of data (block length) is determined by the flow controller. For transfers
between the DMAC and memory, a block is broken directly into a sequence of AMBA bursts and AMBA single
transfers. For transfers between the DMAC and a non-memory peripheral, a block is broken into a sequence of
DMAC transactions (single and bursts). These are in turn broken into a sequence of AMBA transfers.
Transaction: A basic unit of a DMAC transfer as determined by either the hardware or software handshaking
interface. A transaction is only relevant for transfers between the DMAC and a source or destination peripheral if
the source or destination peripheral is a non-memory device. There are two types of transactions: single and burst.
 Single transaction: The length of a single transaction is always 1 and is converted to a single AMBA
transfer.
 Burst transaction: The length of a burst transaction is programmed into the DMAC. The burst
transaction is converted into a sequence of AMBA bursts and AMBA single transfers. DMAC executes
each AMBA burst transfer by performing incremental bursts that are no longer than the maximum
AMBA burst size set. The burst transaction length is under program control and normally bears some
relationship to the FIFO sizes in the DMAC and in the source and destination peripherals.
DMA transfer: Software controls the number of blocks in a DMAC transfer. Once the DMA transfer has
completed, then hardware within the DMAC disables the channel and can generate an interrupt to signal the
completion of the DMA transfer. You can then re-program the channel for a new DMA transfer.
DMAC Transfer
DMA Transfer
Level
Block
Block Block
Block Transfer
Level
Burst
Transaction
Burst
Transaction
Burst
Transaction
Single
Transaction
DMA Transaction
Level
Burst
Transfer
AMBA
Burst
Transfer
AMBA
Burst
Transfer
AMBA
Single
Transfer
AMBA
AMBA Transfer
Level
Single
Transfer
AMBA
DMAC Transfer
DMA Transfer
Level
Block
Block Block
Block Transfer
Level
Burst
Transfer
AMBA
Burst
Transfer
AMBA
Burst
Transfer
AMBA
Single
Transfer
AMBA
AMBA Transfer
Level