GD32F20x User Manual
231
12.3.
Block diagram
Figure 12-1. Block diagram of DMA
Arbiter
AHB
Master
Port
DMA
Configuration
C
on
tr
o
l
&
d
at
a
M
U
X
Channel 0
Channel 1
Channel 2
Channel 6
Memory control
state & counter
management
Peripheral control
state & counter
management
AHB slave
interface
AHB master
interface
…
…
…
…
peri_req
peri_req
peri_req
peri_req
Transfer
request
As shown in
Figure 12-1. Block diagram of DMA
, a DMA controller consists of four main
parts:
DMA configuration through AHB slave interface
Data transmission through two AHB master interfaces for memory access and peripheral
access
An arbiter inside to manage multiple peripheral requests coming at the same time
Channel management to control address/data selection and data counting
12.4.
Function overview
12.4.1.
DMA operation
Each DMA transfer consists of two operations, including the loading of data from the source
and the storage of the loaded data to the destination. The source and destination addresses
are computed by the DMA controller based on the programmed values in the
DMA_CHxPADDR, DMA_CHxMADDR, and DMA_CHxCTL registers. The DMA_CHxCNT
register controls how many transfers to be transmitted on the channel. The PWIDTH and
MWIDTH bits in the DMA_CHxCTL register determine how many bytes to be transmitted in a
transfer. Normal transfer mode or Full_Data transfer mode can be set using the FD_CH5EN
bit in the DMA_ACFG register.
The CNT bits in the DMA_CHxCNT register control how many data to be transmitted on the
channel and must be configured before enable the CHEN bit in the register. During the
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