Module dma

Available on crate feature unstable only.

Direct Memory Access (DMA)

Overview

The DMA driver provides an interface to efficiently transfer data between different memory regions and peripherals within the ESP microcontroller without involving the CPU. The DMA controller is responsible for managing these data transfers.

Notice, that this module is a common version of the DMA driver, ESP32 and ESP32-S2 are using older PDMA controller, whenever other chips are using newer GDMA controller.

Examples

Initialize and utilize DMA controller in SPI

let dma_channel = peripherals.DMA_SPI2;
let sclk = peripherals.GPIO0;
let miso = peripherals.GPIO2;
let mosi = peripherals.GPIO4;
let cs = peripherals.GPIO5;

let mut spi = Spi::new(
    peripherals.SPI2,
    Config::default().with_frequency(100.kHz()).with_mode(Mode::_0)
)
.unwrap()
.with_sck(sclk)
.with_mosi(mosi)
.with_miso(miso)
.with_cs(cs)
.with_dma(dma_channel);

⚠️ Note: Descriptors should be sized as (max_transfer_size + CHUNK_SIZE - 1) / CHUNK_SIZE. I.e., to transfer buffers of size 1..=CHUNK_SIZE, you need 1 descriptor.

⚠️ Note: For chips that support DMA to/from PSRAM (ESP32-S3) DMA transfers to/from PSRAM have extra alignment requirements. The address and size of the buffer pointed to by each descriptor must be a multiple of the cache line (block) size. This is 32 bytes on ESP32-S3.

For convenience you can use the crate::dma_buffers macro.

Re-exports

• pub use as_mut_byte_array;

Structs

• AnyI2sDmaChannel
  An I2S-compatible type-erased DMA channel.
• AnyI2sDmaRxChannel
  The RX half of an arbitrary I2S DMA channel.
• AnyI2sDmaTxChannel
  The TX half of an arbitrary I2S DMA channel.
• AnySpiDmaChannel
  An SPI-compatible type-erased DMA channel.
• AnySpiDmaRxChannel
  The RX half of an arbitrary SPI DMA channel.
• AnySpiDmaTxChannel
  The TX half of an arbitrary SPI DMA channel.
• BufView
  An in-progress view into DmaRxBuf/DmaTxBuf.
• Channel
  DMA Channel
• DmaDescriptor
  A DMA transfer descriptor.
• DmaDescriptorFlags
  DMA descriptor flags.
• DmaLoopBuf
  DMA Loop Buffer
• DmaRxBuf
  DMA receive buffer
• DmaRxStreamBuf
  DMA Streaming Receive Buffer.
• DmaRxStreamBufView
  A view into a DmaRxStreamBuf
• DmaRxTxBuf
  DMA transmit and receive buffer.
• DmaTransferRx
  DMA transaction for RX only transfers
• DmaTransferRxCircular
  DMA transaction for RX only circular transfers
• DmaTransferRxTx
  DMA transaction for TX+RX transfers
• DmaTransferTx
  DMA transaction for TX only transfers
• DmaTransferTxCircular
  DMA transaction for TX only circular transfers
• DmaTxBuf
  DMA transmit buffer
• EmptyBuf
  An empty buffer that can be used when you don’t need to transfer any data.
• I2s0DmaChannel
  DMA channel suitable for I2S0
• I2s1DmaChannel
  DMA channel suitable for I2S1
• Preparation
  Holds all the information needed to configure a DMA channel for a transfer.
• Spi2DmaChannel
  DMA channel suitable for SPI2
• Spi3DmaChannel
  DMA channel suitable for SPI3

Enums

• BurstConfig
  Burst transfer configuration.
• DmaAlignmentError
  DMA buffer alignment errors.
• DmaBufError
  Error returned from Dma[Rx|Tx|RxTx]Buf operations.
• DmaError
  DMA Errors
• DmaInterrupt
  Kinds of interrupt to listen to.
• DmaPriority
  DMA Priorities The values need to match the TRM
• DmaRxInterrupt
  Types of interrupts emitted by the RX channel.
• DmaTxInterrupt
  Types of interrupts emitted by the TX channel.
• Owner
  The owner bit of a DMA descriptor.
• TransferDirection
  The direction of the DMA transfer.

Constants

• CHUNK_SIZE
  The default chunk size used for DMA transfers.

Traits

• DmaChannel
  A description of a DMA Channel.
• DmaChannelFor
  Trait implemented for DMA channels that are compatible with a particular peripheral.
• DmaRxBuffer
  DmaRxBuffer is a DMA descriptor + memory combo that can be used for receiving data from a peripheral’s FIFO to a DMA channel.
• DmaTxBuffer
  DmaTxBuffer is a DMA descriptor + memory combo that can be used for transmitting data from a DMA channel to a peripheral’s FIFO.
• ReadBuffer
  Trait for buffers that can be given to DMA for reading.
• RxChannelFor
  Trait implemented for the RX half of split DMA channels that are compatible with a particular peripheral. Accepts complete DMA channels or split halves.
• TxChannelFor
  Trait implemented for the TX half of split DMA channels that are compatible with a particular peripheral. Accepts complete DMA channels or split halves.
• WriteBuffer
  Trait for buffers that can be given to DMA for writing.

Functions

• descriptor_count
  Computes the number of descriptors required for a given buffer size with a given chunk size.

Type Aliases

• PeripheralDmaChannel
  Helper type to get the DMA (Rx and Tx) channel for a peripheral.
• PeripheralRxChannel
  Helper type to get the DMA Rx channel for a peripheral.
• PeripheralTxChannel
  Helper type to get the DMA Tx channel for a peripheral.