ADSP-BF537 Blackfin Processor Hardware Reference
5-11
Direct Memory Access
To start an MDMA transfer operation, the MMRs for the source and des-
tination channels are written, each in a manner similar to peripheral
DMA.
L
Note the
DMAx_CONFIG
register for the source channel must be writ-
ten before the
DMAx_CONFIG
register for the destination channel.
Handshaked Memory DMA Mode
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 trigger 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 to control the timing of mem-
ory-to-memory transfers, it also enables the MDMA to operate with
asynchronous FIFO-style devices connected to the EBIU port. The Black-
fin processor acknowledges a DMA request by a proper number of read or
write operations. It is up to the device connected to any of the
MSx
strobes
to deassert or pulse the request signal and to decrement the number of
pending requests accordingly.
Depending on HMDMA operating mode, an external DMA request may
trigger individual data word transfers or block transfers. A block can con-
sist of up to 65535 data words. For best throughput, DMA requests can
be pipelined. The HMDMA controllers feature a request counter to
decouple request timing from the data transfers.
See
“Handshaked Memory DMA Operation” on page 5-40
for a func-
tional description.
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 ...