TMS320VC5416 datasheet(37/98 Pages) TI1

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3.12 DMA Controller

3.12.1

Features

3.12.2 DMA External Access

TMS320VC5416

Fixed-Point Digital Signal Processor

www.ti.com

SPRS095P – MARCH 1999 – REVISED OCTOBER 2008

The device direct memory access (DMA) controller transfers data between points in the memory map

without intervention by the CPU. The DMA allows movements of data to and from internal program/data

memory, internal peripherals (such as the McBSPs), or external memory devices to occur in the

background of CPU operation. The DMA has six independent programmable channels, allowing six

different contexts for DMA operation.

The DMA has the following features:

• The DMA operates independently of the CPU.

• The DMA has six channels. The DMA can keep track of the contexts of six independent block

transfers.

• The DMA has higher priority than the CPU for both internal and external accesses.

• Each channel has independently programmable priorities.

• Each channel's source and destination address registers can have configurable indexes through

memory on each read and write transfer, respectively. The address may remain constant, be

post-incremented, be post-decremented, or be adjusted by a programmable value.

• Each read or write internal transfer may be initialized by selected events.

• On completion of a half- or entire-block transfer, each DMA channel may send an interrupt to the CPU.

• The DMA can perform double-word internal transfers (a 32-bit transfer of two 16-bit words).

The DMA supports external accesses to data, I/O, and extended program memory. These overlay pages

are only visible to the DMA controller. A maximum of two DMA channels can be used for external memory

accesses. The DMA external accesses require a minimum of 8 cycles for external writes and a minimum

of 11 cycles for external reads assuming the XIO02 is in consecutive mode (CONSEC = 1), wait state is

set to two, and CLKOUT is not divided (DIVFCT = 00).

The control of the bus is arbitrated between the CPU and the DMA. While the DMA or CPU is in control of

the external bus, the other will be held-off via wait states until the current transfer is complete. The DMA

takes precedence over XIO requests.

• Only two channels are available for external accesses. (One for external reads and one for external

writes.)

• Single-word (16-bit) transfers are supported for external accesses.

• The DMA does not support transfers from the peripherals to external memory.

• The DMA does not support transfers from external memory to the peripherals.

• The DMA does not support external-to-external accesses.

• The DMA does not support synchronized external accesses.

AUTOINIT

DINM

IMOD

CTMOD

SLAXS

SIND

DMS

DLAXS

DIND

DMD

LEGEND: R = Read, W = Write, n = value present after reset

Figure 3-16. DMA Transfer Mode Control Register (DMMCRn)

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