
Functional Description
5-28
ADSP-BF59x Blackfin Processor Hardware Reference
descriptor chains. DMA transmit (memory read) channels may
have such restrictions (see
“DMA Transmit and MDMA Source”
on page 5-25
).
Stopping DMA Transfers
In
FLOW
= 0 mode, DMA stops automatically after the work unit is
complete.
If a list or array of descriptors is used to control DMA, and if every
descriptor contains a
DMACFG
element, then the final
DMACFG
element
should have a
FLOW
= 0 setting to gracefully stop the channel.
In autobuffer (
FLOW
= 1) mode, or if a list or array of descriptors without
DMACFG
elements is used, then the DMA transfer process must be termi-
nated by an MMR write to the
DMAx_CONFIG
register with a value whose
DMAEN
bit is 0. A write of 0 to the entire register will always terminate
DMA gracefully (without DMA abort).
If a channel has been stopped abruptly by writing
DMAx_CONFIG
to 0
(or any value with
DMAEN
= 0), the user must ensure that any mem-
ory read or write accesses in the pipelines have completed before
enabling the channel again. If the channel is enabled again before
an “orphan” access from a previous work unit completes, the state
of the DMA interrupt and FIFO is unspecified. This can generally
be handled by ensuring that the core allocates several consecutive
idle cycles in its usage of the relevant memory space to allow up to
three pending DMA accesses to issue, plus allowing enough mem-
ory access time for the accesses themselves to complete.
DMA Errors (Aborts)
The DMA controller flags conditions that cause the DMA process to end
abnormally (abort). This functionality is provided as a tool for system
development and debug to detect DMA-related programming errors.
DMA errors (aborts) are detected by the DMA channel module in the
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...