Quick DMA (QDMA)
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6.16 Quick DMA (QDMA)
QDMA, or quick DMA, provides one of the most efficient ways to move data
around in the ’C6211 architecture. Quick DMA supports nearly all of the same
transfer modes of the EDMA. However, as the name implies, QDMA submits
transfer requests more quickly than the EDMA. In a typical system, the user
will use the EDMA for periodic real-time peripheral servicing, such as providing
the McBSP with transmit data at a regular rate. For some applications, howev-
er, data must be moved in blocks under direct control of the code running on
the CPU. For these applications, the QDMA is ideally suited.
6.16.1 QDMA Registers
The QDMA is supported through two sets of memory-mapped registers. The
first set of five memory-mapped registers contains parameters that define a
QDMA transfer, similar to the EDMA transfer parameters. The second set of
five memory-mapped registers is a pseudo-mapping of the registers in the first
set. The pseudo-mapping registers optimize the QDMA performance.
Figure 6–18 shows the five memory mapped registers, and Figure 6–19
shows the five pseudo-mapping registers.
Figure 6–18. QDMA Memory-Mapped Registers
31 0
QDMA_OPT
QDMA options
0200 0000h
31 0
QDMA_SRC
SRC address
0200 0004h
31 16
15 0
QDMA_CNT
Arrary/frame count
Element count
0200 0008h
31 0
QDMA_DST
DST address
0200 000ch
31 16
15 0
QDMA_IDX
Arrary/frame index
Element index
0200 0010h