DMA controller (DMA)
RM0090
308/1731
DocID018909 Rev 11
Figure 34. System implementation of the two DMA controllers (STM32F42xxx and
STM32F43xxx)
1. The DMA1 controller AHB peripheral port is not connected to the bus matrix like in the case of the DMA2
controller, thus only DMA2 streams are able to perform memory-to-memory transfers.
10.3.2 DMA
transactions
A DMA transaction consists of a sequence of a given number of data transfers. The number
of data items to be transferred and their width (8-bit, 16-bit or 32-bit) are software-
programmable.
Each DMA transfer consists of three operations:
•
A loading from the peripheral data register or a location in memory, addressed through
the DMA_SxPAR or DMA_SxM0AR register
•
A storage of the data loaded to the peripheral data register or a location in memory
addressed through the DMA_SxPAR or DMA_SxM0AR register
•
A post-decrement of the DMA_SxNDTR register, which contains the number of
transactions that still have to be performed
-36
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