Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
134
/
631
Block diagram
Figure 7-1 DMA block diagram
Function description
DMA controller and Cortex™-M4F core share the same system data bus. When CPU and DMA access the same
target (RAM or peripheral) at the same time, DMA request will suspend CPU from accessing the system bus for
several cycles, and the bus arbiter will perform cyclic scheduling. This allows the CPU to get at least half of the
system bus (memory or peripheral) bandwidth.
DMA operation
A DMA request can be triggered by hardware peripherals or software, and the DMA controller processes the request
according to the priority level of the channel. The data is read from the source address according to the configured
transfer address and bit width, and then the read data is stored in the destination address space. After one operation,
the controller calculates the number of remaining transfers and updates the source address and the destination address
Cortex-M4F
B
us
m
at
ri
x
DMA
Flash
Interface
controller
DMA
CH1
CH2
CH8
AHB slave
device
Arbiter
Bridge 1
Bridge 2
DMA requests
Flash
SRAM
ADC
DAC
I2C1
I2C2
USART2
USART1
UART4
UART5
USART3
LPUART
TIM2
TIM3
SPI1
TIM1
APB
1
APB
2
SPI2
TIM8
DMA requests
TIM4
TIM5
TIM6
TIM7
TIM9