Module dma

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Available on crate feature unstable only.

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§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_CH0;
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(Rate::from_khz(100)).
with_mode(Mode::_0) )?
.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§

AnyGdmaChannel: An arbitrary GDMA channel
AnyGdmaRxChannel: An arbitrary GDMA RX channel
AnyGdmaTxChannel: An arbitrary GDMA TX channel
BufView: An in-progress view into DmaRxBuf/DmaTxBuf.
Channel: DMA Channel
DmaChannel0: A description of a specific GDMA channel
DmaChannel1: A description of a specific GDMA channel
DmaChannel2: A description of a specific GDMA 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.
Mem2Mem: DMA Memory to Memory pseudo-Peripheral
Preparation: Holds all the information needed to configure a DMA channel for a transfer.

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
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.

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