Note

This component is currently in beta. Its API, behavior, and compatibility may change at any time and without notice; backward compatibility is not guaranteed. Use caution when integrating into production systems.

Overview

The esp_hal_dma component provides a Hardware Abstraction Layer for Direct Memory Access (DMA) controllers across all ESP-IDF supported targets. DMA allows peripherals to access memory directly without CPU intervention, significantly improving data transfer efficiency and reducing CPU load.

Architecture

The DMA HAL is structured in two main sub-layers:

HAL Layer (Upper): Defines the operational steps and data structures required to control DMA peripherals (e.g., initialization, channel configuration, transfer start/stop).
Low-Level Layer (Bottom): Serves as a translation layer between the HAL and the register files defined in the soc component, handling target-specific register configurations.

Supported DMA Controllers

This HAL supports various DMA controller types depending on the ESP chip:

GDMA (General DMA): Available in multiple versions:
- AHB GDMA (Version 1 & 2)
- AXI GDMA
DW GDMA: DesignWare DMA controller
DMA2D: 2D DMA controller for efficient image processing operations
CP DMA: A dedicated DMA controller designed for highly efficient memory copy

Features

Channel allocation and management
Transfer direction control (TX/RX)
Trigger peripheral selection (M2M, SPI, I2S, etc.)
Priority configuration for channels
DMA descriptor handling
CRC calculation support (on supported chips)
ETM (Event Task Matrix) event handling

Usage

The HAL functions primarily serve ESP-IDF peripheral drivers such as esp_private/gdma.h.

Advanced developers can use these interfaces directly when implementing custom drivers, with the understanding that API stability is not guaranteed.

Dependencies

soc: Provides chip-specific register definitions
hal: Core hardware abstraction utilities and macros