Functional Description
5-48
ADSP-BF537 Blackfin Processor Hardware Reference
Memory DMA Timing Details
When the destination
DMAx_CONFIG
register is written, MDMA operation
starts, after a latency of 3
SCLK
cycles.
First, if either MDMA channel has been selected to use descriptors, the
descriptors are fetched from memory. The destination channel descriptors
are fetched first. Then, after a latency of 4
SCLK
cycles after the last
descriptor word is returned from memory (or typically 8
SCLK
cycles after
the fetch of the last descriptor word, due to memory pipelining), the
source MDMA channel begins fetching data from the source buffer. The
resulting data is deposited in the MDMA channel’s 8-location FIFO, and
then after a latency of 2
SCLK
cycles, the destination MDMA channel
begins writing data to the destination memory buffer.
Static Channel Prioritization
DMA channels are ordinarily granted service strictly according to their
priority. The priority of a channel is simply its channel number, where
lower priority numbers are granted first. Thus, peripherals with high data
rates or low latency requirements should be assigned to lower numbered
(higher priority) channels using the
PMAP
field in the
DMAx_PERIPHERAL_
MAP
registers. The memory DMA streams are always lower static priority
than the peripherals, but as they request service continuously, they ensure
that any time slots unused by peripheral DMA are applied to MDMA
transfers.
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 ...