
Logical channel
activation
HW DMA requests/
SW enable bit
Write port
Data
FIFO pool
manager
Each FIFO is
associated to an
active logical
channel
Logical Channel 0
Logical channel
context 0
Request
High
prio.
Low
prio.
FIFO pool
Logical
channel
scheduler
Port
access
scheduler
Priority
queues
High
prio.
Low
prio.
Logical
channel
scheduler
Port
access
scheduler
Priority
queues
Read port
Data
Request
C1
C2
C3
C4
dma-006
Public Version
SDMA Functional Description
www.ti.com
11.4 SDMA Functional Description
The SDMA module provides high-performance data transfers between memories and peripheral devices
with low processor use. A DMA transfer is programmed through a logical DMA channel, which allows the
transfer to be optimally tailored to the requirements of the application.
shows the SDMA controller top-level block diagram.
Figure 11-6. SDMA Controller Top-Level Block Diagram
11.4.1 Logical Channel Transfer Overview
As
shows, the SDMA module has one read port and one write port operating independently of
each other. Buffering is provided between the read and write ports through a FIFO queue memory pool
that is shared dynamically between the active logical channels.
•
Logical channel synchronization
A logical channel is described as hardware-synchronized when the DMA transfers are triggered by
DMA requests from a hardware device. Alternatively, a logical channel is described as
nonsynchronized when the DMA transfer is triggered by software.
•
Logical channel activation
A logical channel becomes active as follows:
2346
SDMA
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated