Flow Control; Circular Mode; Table 7-2 Flow Control Table - Nations N32G430 Series User Manual

If software is used to serve interrupt, software must enquire interrupt status register to check which interrupt occurred
(software needs to write 1 to interrupt flag clear bit to clear the corresponding interrupt). Before enable channel, all
interrupts corresponding to the channel should be cleared.
If the interrupt is transfer complete interrupt, software can configure the next transfer, or report to user this channel
transformation is done.

Flow control

Three major flow controls are supported:
 Memory to memory
 Memory to peripheral
 Peripheral to memory
Flow control is controlled by two register bits in each DMA channel configuration register. Flow control is used to
control source/destination and direction of DMA channel.
DMA_CHCFGx.MEM2MEM DMA_CHCFGx.DIR
1
0
0

Circular mode

The circular mode is used to process circular buffers and continuous data transmission (such as ADC scan mode).
The DMA_CHCFGx.CIRC is used to enable this function. When the cyclic mode is activated, if the number of data
to be transferred becomes 0, it will automatically be restored to the initial value when configuring the channel, and
the DMA operation will continue.
If the user wants to turn off the circular mode, the user needs to write 0 to DMA_CHCFGx.CHEN to disable the
DMA channel, and then write 0 to DMA_CHCFGx.CIRC (when DMA_CHCFGx.CHEN is 1, other bits in the

Table 7-2 Flow control table

Source
x Memory
1
Memory
AHB
Peripheral
0
APB
Peripheral
195 / 647
Destination
AHB read to AHB write, can do back2back
Memory
AHB
AHB read to AHB write, single transfer
Peripheral
APB
AHB read to APB write, single transfer
Peripheral
AHB read to AHB write, single transfer
Memory
APB read to AHB write, single transfer
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