ST STM32F301 6 Series Reference Manual page 159

RM0366
Note: If the channel x is disabled, the DMA registers are not reset. The DMA channel registers
(DMA_CCRx, DMA_CPARx and DMA_CMARx) retain the initial values programmed during
the channel configuration phase.
In circular mode, after the last data transfer, the DMA_CNDTRx register is automatically
reloaded with the initially programmed value. The current internal address registers are
reloaded with the base address values from the DMA_CPARx and DMA_CMARx registers.
Channel configuration procedure
The following sequence is needed to configure a DMA channel x:
1. Set the peripheral register address in the DMA_CPARx register.
The data is moved from/to this address to/from the memory after the peripheral event,
or after the channel is enabled in memory-to-memory mode.
2. Set the memory address in the DMA_CMARx register.
The data is written to/read from the memory after the peripheral event or after the
channel is enabled in memory-to-memory mode.
3. Configure the total number of data to transfer in the DMA_CNDTRx register.
After each data transfer, this value is decremented.
4. Configure the parameters listed below in the DMA_CCRx register:
–
–
–
–
–
–
5. Activate the channel by setting the EN bit in the DMA_CCRx register.
A channel, as soon as enabled, may serve any DMA request from the peripheral connected
to this channel, or may start a memory-to-memory block transfer.
Note: The two last steps of the channel configuration procedure may be merged into a single
access to the DMA_CCRx register, to configure and enable the channel.
Channel state and disabling a channel
A channel x in the active state is an enabled channel (read DMA_CCRx.EN = 1). An active
channel x is a channel that must have been enabled by the software (DMA_CCRx.EN set
to 1) and afterwards with no occurred transfer error (DMA_ISR.TEIFx = 0). In case there is a
transfer error, the channel is automatically disabled by hardware (DMA_CCRx.EN = 0).
the channel priority
the data transfer direction
the circular mode
the peripheral and memory incremented mode
the peripheral and memory data size
the interrupt enable at half and/or full transfer and/or transfer error
Direct memory access controller (DMA)
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