Direct Memory Access Controller (Dma); Introduction; Dma Main Features - ST STM32L0x3 Reference Manual

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Direct memory access controller (DMA)

11.1

Introduction

The direct memory access (DMA) controller is a bus master and system peripheral.
The DMA is used to perform programmable data transfers between memory-mapped
peripherals and/or memories, upon the control of an off-loaded CPU.
The DMA controller features a single AHB master architecture.
There is one instance of DMA with 7 channels.
Each channel is dedicated to managing memory access requests from one or more
peripherals. The DMA includes an arbiter for handling the priority between DMA requests.
11.2

DMA main features

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Single AHB master
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Peripheral-to-memory, memory-to-peripheral, memory-to-memory and peripheral-to-
peripheral data transfers
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Access, as source and destination, to on-chip memory-mapped devices such as Flash
memory, SRAM, and AHB and APB peripherals
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All DMA channels independently configurable:
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Generation of an interrupt request per channel. Each interrupt request is caused from
any of the three DMA events: transfer complete, half transfer, or transfer error.
Each channel is associated either with a DMA request signal coming from a
peripheral, or with a software trigger in memory-to-memory transfers. This
configuration is done by software.
Priority between the requests is programmable by software (4 levels per channel:
very high, high, medium, low) and by hardware in case of equality (such as
request to channel 1 has priority over request to channel 2).
Transfer size of source and destination are independent (byte, half-word, word),
emulating packing and unpacking. Source and destination addresses must be
aligned on the data size.
Support of transfers from/to peripherals to/from memory with circular buffer
management
Programmable number of data to be transferred: 0 to 2
Direct memory access controller (DMA)
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