ST STM32F205 series Reference Manual page 177

RM0033
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Each stream can be configured by hardware to be:
–
–
• Each of the 8 streams are connected to dedicated hardware DMA channels (requests)
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Priorities between DMA stream requests are software-programmable (4 levels
consisting of very high, high, medium, low) or hardware in case of equality (request 0
has priority over request 1, etc.)
•
Each stream also supports software trigger for memory-to-memory transfers (only
available for the DMA2 controller)
• Each stream request can be selected among up to 8 possible channel requests. This
selection is software-configurable and allows several peripherals to initiate DMA
requests
•
The number of data items to be transferred can be managed either by the DMA
controller or by the peripheral:
–
–
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Independent source and destination transfer width (byte, half-word, word): when the
data widths of the source and destination are not equal, the DMA automatically
packs/unpacks the necessary transfers to optimize the bandwidth. This feature is only
available in FIFO mode
•
Incrementing or non-incrementing addressing for source and destination
•
Supports incremental burst transfers of 4, 8 or 16 beats. The size of the burst is
software-configurable, usually equal to half the FIFO size of the peripheral
•
Each stream supports circular buffer management
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5 event flags (DMA Half Transfer, DMA Transfer complete, DMA Transfer Error, DMA
FIFO Error, Direct Mode Error) logically ORed together in a single interrupt request for
each stream
FIFO to ensure an immediate data transfer as soon as a DMA request is triggered
by a peripheral.
a regular channel that supports peripheral-to-memory, memory-to-peripheral and
memory-to-memory transfers
a double buffer channel that also supports double buffering on the memory side
DMA flow controller: the number of data items to be transferred is software-
programmable from 1 to 65535
Peripheral flow controller: the number of data items to be transferred is unknown
and controlled by the source or the destination peripheral that signals the end of
the transfer by hardware
RM0033 Rev 8
DMA controller (DMA)
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