ADSP-BF537 Blackfin Processor Hardware Reference
5-45
Direct Memory Access
• How often do competing DMA channels require the bus systems to
alter direction?
• How often do competing DMA or core accesses cause the SDRAM
to open different pages?
• Is there a way to distribute DMA requests nicely over time?
A key feature of the DMA architecture is the separation of the activity on
the peripheral DMA bus (the DMA Access Bus (DAB)) from the activity
on the buses between the DMA and memory (the DMA Core Bus (DCB)
and the DMA External Bus (DEB)).
Chapter 2, “Chip Bus Hierarchy”
explains the bus architecture.
Each peripheral DMA channel has its own data FIFO which lies between
the DAB bus and the memory buses. These FIFOs automatically prefetch
data from memory for transmission and buffer received data for later
memory writes. This allows the peripheral to be granted a DMA transfer
with very low latency compared to the total latency of a pipelined memory
access, permitting the repeat rate (bandwidth) of each DMA channel to be
as fast as possible.
DMA Throughput
Peripheral DMA channels have a maximum transfer rate of one 16-bit
word per two system clocks, per channel, in either direction. As the DAB
and DEB buses do, the DMA controller resides in the
SCLK
domain. The
controller synchronizes accesses to and from the DCB bus which is run-
ning at
CCLK
rate.
Memory DMA channels have a maximum transfer rate of one 16-bit word
per one system clock (
SCLK
), per channel.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...