Functional Description
5-40
ADSP-BF537 Blackfin Processor Hardware Reference
Handshaked Memory DMA Operation
Both
DMARx
inputs have their own set of control and status registers.
Handshake operation for MDMA0 is enabled by the
HMDMAEN
bit in the
HMDMA0_CONTROL
register. Similarly, the
HMDMAEN
bit in the
HMDMA1_CONTROL
register enables handshake mode for MDMA1.
It is important to understand that the handshake hardware works com-
pletely independent from the descriptor and autobuffer capabilities of the
MDMA, allowing most flexible combinations of logical data organization
vs. data portioning as required by FIFO deeps, for example. If, however,
the connected device requires certain behavior of the address lines, these
must be controlled by traditional DMA setup.
L
The HMDMA unit controls only the destination (memory write)
channel of the memory DMA. The source channel (memory-read
side) fills the 8-depth DMA buffers immediately after the receive
being enabled issues 8 read commands.
The
HMDMAx_BCINIT
registers control how many data transfers are per-
formed upon every DMA request. If set to one, the peripheral can time
every individual data transfer. If greater than one, the peripheral must fea-
ture sufficient buffer size to provide or consume the number of words
programmed. Once the transfer has been requested, no further handshake
can hold off the DMA from transferring the entire block, except by stall-
ing the EBIU accesses by the
ARDY
signal or a complete bus request and
grant cycle through the
BR
and
BG
pins. Nevertheless, the peripheral may
request a block transfer before the entire buffer is available, by simply tak-
ing the minimum transfer time based on wait-state settings into
consideration.
L
The block count defines how many data transfers are performed by
the MDMA engine. A single DMA transfer can cause two read or
write operations on the EBIU port if the transfer word size is set to
32 bit in the
MDMA_yy_CONFIG
register (
WDSIZE
=
b#10
).
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 ...