
DMA Controller Overview
5-8
ADSP-BF59x Blackfin Processor Hardware Reference
destination DMA engine empties it. The FIFO depth allows the burst
transfers of the external access bus (EAB) and DMA access bus (DAB) to
overlap, significantly improving throughput on block transfers between
internal and external memory. Two separate descriptor blocks are required
to supply the operating parameters for each MDMA pair, one for the
source channel and one for the destination channel.
Because the source and destination DMA engines share a single FIFO buf-
fer, the descriptor blocks must be configured to have the same data size. It
is possible to have a different mix of descriptors on both ends as long as
the total transfer count is the same.
To start a MDMA transfer operation, the MMRs for the source and desti-
nation channels are written, each in a manner similar to peripheral DMA.
The
DMAx_CONFIG
register for the source channel must be written
before the
DMAx_CONFIG
register for the destination channel.
Handshaked Memory DMA (HMDMA) Mode
This feature is not available for all products. Refer to the
“Unique Infor-
mation for the ADSP-BF59x Processor” on page 5-101
to determine
whether it applies to this product.
Handshaked operation applies only to memory DMA channels.
Normally, memory DMA transfers are performed at maximum speed.
Once started, data is transferred in a continuous manner until either the
data count expires or the MDMA is stopped. In handshake mode, the
MDMA does not transfer data automatically when enabled; it waits for an
external trigger on the MDMA request input signals. The
DMAR0
input is
associated with MDMA0 and the
DMAR1
input with MDMA1. Once a trig-
ger event is detected, a programmable portion of data is transferred and
then the MDMA stalls again and waits for the next trigger.
Handshake operation is not only useful for controlling the timing of
memory-to-memory transfers, it also enables the MDMA to operate with
Содержание ADSP-BF59x Blackfin
Страница 64: ...Development Tools 1 22 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 204: ...Unique Information for the ADSP BF59x Processor 5 104 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 244: ...Programming Examples 6 40 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 345: ...ADSP BF59x Blackfin Processor Hardware Reference 9 9 Core Timer Unique Information for the ADSP BF59x Processor None...
Страница 346: ...Unique Information for the ADSP BF59x Processor 9 10 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 398: ...Unique Information for the ADSP BF59x Processor 11 42 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 622: ...Unique Information for the ADSP BF59x Processor 15 38 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 700: ...Programming Examples 16 78 ADSP BF59x Blackfin Processor Hardware Reference...
Страница 738: ...Boundary Scan Architecture B 8 ADSP BF59x Blackfin Processor Hardware Reference...