OMAP5912 Datasheet, PDF (182/254 Pages) Texas Instruments – Applications Processor

Functional Overview
3.9 System DMA Controller
The system direct memory access (DMA) controller transfers data between points in the memory space
without intervention by the MPU. The system DMA allows movements of data to and from internal memory,
external memory, and peripherals to occur in the background of MPU operation. It is designed to off-load the
block data transfer function from the MPU processor. The system DMA is configured by the MPU via the MPU
private peripheral bus.
System DMA consists of:
• Seventeen logical channels
• Seven physical ports + one for configuration
• Four physical channels
The ports are connected to the L3 OCP targets, the external memory, the TIPB bridge, the MPUI, and one
dedicated port connected to an LCD controller. The system DMA controller can be controlled via the MPU
private TIPB or by an external host via the OCP-I port. The system DMA controller is designed for low-power
operation. It is partitioned into several clock domains where each clock domain is enabled only when it is used.
All clocks are disabled when no DMA transfers are active (synchronous to the MPU TIPB, this feature is totally
under hardware control; no specific programming is needed). Five different logical channels types are
supported; each one represents a specific feature set:
• LCh-2D for memory-to-memory transfers, 1D and 2D
• LCh-P for peripheral transfers
• LCh-PD for peripheral transfers on a dedicated channel
• LCh-G for graphical transfers/operations
• LCh-D for display transfers
The available features are:
• Support for up to four address modes:
− Constant
− Post-increment
− Single indexing
− Double indexing
• Different indexing for source-respective destination
• Logical channel chaining
• Software enabling
• Hardware enabling
• Logical channel interleaving
• Logical channel preemption
• Two choices of logical channel arbitration of physical resources: round robin or fixed
• Two levels of logical channel priority
• Constant fill
• Transparent copy
• Rotation 0, 90, 180, and 270
182 SPRS231D
December 2003 − Revised March 2005