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W7500x Reference Manual Version1.1.0
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19
Direct memory access controller (DMA)
19.1
Introduction
Direct memory access (DMA) is used in order to provide high-speed data transfer between
peripherals and memory as well as memory to memory. Data can be quickly moved by DMA
without any CPU actions. This keeps CPU resources free for other operations.
The DMA controller has up to 6 channels in total, each dedicated to managing memory access
requests from one or more peripherals. It has an arbiter for handling the priority between DMA
requests. For more details, refer to “PrimeCell® μDMA Controller (PL230)” from the Technical
Reference Manual
19.2
Features
• 6 channels
• Each channel is connected to dedicated hardware DMA requests and software trigger is
also supported on each channel.
• Priorities between requests from the DMA channels are software programmable (2 levels
consisting of high, default)
• Memory-to-memory transfer (software request only)
• TCP/IP-to-memory transfer (software request only)
• SPI/UART-to-memory transfer (hardware request and software request)
• Access to Flash, SRAM, APB and AHB peripherals as source and destination
19.3
Functional description
Figure 17 shows the DMA block diagram.
GPIO x 16
CM0
AHB-Lite BUS
Flash
Flash
Interface
SRAM
Controller
SRAM
uDMA
(PL230)
TCP/IP
GPIOA/GPIOB
GPIOC/GPIOD
SRAM
A
PB
B
U
S
Other
APB
Peripherals
APB
Bridge
UART0
SPI0
SPI1
UART1
DMA request
Figure 17. DMA Block diagram