DMADRV - DMA Driver#

Direct Memory Access Driver.

Introduction#

The DMADRV driver supports writing code using DMA which will work regardless of the type of the DMA controller on the underlying microcontroller. Additionally, DMA can be used in several modules that are completely unaware of each other. The driver does not preclude use of the native emlib or peripheral API of the underlying DMA controller. On the contrary, it will often result in more efficient code and is necessary for complex DMA operations. The housekeeping functions of this driver are valuable even in this use-case.

The dmadrv.c and dmadrv.h source files are in the emdrv/dmadrv folder.

Note

• DMA transfer completion callback functions are called from within the DMA interrupt handler. On versions of the DMA controller with one interrupt per channel, the callback function is called from its respective channel interrupt handler.

Configuration Options#

Some properties of the DMADRV driver are compile-time configurable. These properties are stored in a file named dmadrv_config.h. A template for this file, containing default values, is in the emdrv/config folder. IC specific versions of dmadrv_config.h files are available in config/sx_xch directories. Currently the configuration options are as follows:

• The interrupt priority of the DMA peripheral.

• A number of DMA channels to support.

• Use the native emlib/peripheral API belonging to the underlying DMA hardware in combination with the DMADRV API.

Both configuration options will help reduce the driver's RAM footprint.

To configure DMADRV, provide a custom configuration file. This is an example dmadrv_config.h file:

#ifndef __SILICON_LABS_DMADRV_CONFIG_H__
#define __SILICON_LABS_DMADRV_CONFIG_H__

  // DMADRV DMA interrupt priority configuration option.
  // Set DMA interrupt priority. Range is 0..7, 0 is the highest priority.
#define EMDRV_DMADRV_DMA_IRQ_PRIORITY 4

  // DMADRV channel count configuration option.
  // A number of DMA channels to support. A lower DMA channel count will reduce
  // RAM footprint.
#define EMDRV_DMADRV_DMA_CH_COUNT 4

#endif
#ifndef __SILICON_LABS_DMADRV_CONFIG_H__
#define __SILICON_LABS_DMADRV_CONFIG_H__

  // DMADRV DMA interrupt priority configuration option.
  // Set DMA interrupt priority. Range is 0..7, 0 is the highest priority.
#define EMDRV_DMADRV_DMA_IRQ_PRIORITY 4

  // DMADRV channel count configuration option.
  // A number of DMA channels to support. A lower DMA channel count will reduce
  // RAM footprint.
#define EMDRV_DMADRV_DMA_CH_COUNT 4

#endif

The API#

This section contains brief descriptions of the API functions. For more information about input and output parameters and return values, click on the hyperlinked function names. Most functions return an error code, ECODE_EMDRV_DMADRV_OK is returned on success, see ECODE - Error Codes and Error Codes for other error codes.

The application code must include dmadrv.h header file.

DMADRV_Init(), DMADRV_DeInit()
These functions initialize or deinitialize the DMADRV driver. Typically, DMADRV_Init() is called once in the startup code.

DMADRV_AllocateChannel(), DMADRV_AllocateChannelById(), DMADRV_FreeChannel()
DMA channel reserve and release functions. It is recommended that application code checks that DMADRV_AllocateChannel() returns ECODE_EMDRV_DMADRV_OK before starting a DMA transfer.

DMADRV_MemoryPeripheral()
Start a DMA transfer from memory to a peripheral.

DMADRV_PeripheralMemory()
Start a DMA transfer from a peripheral to memory.

DMADRV_MemoryPeripheralPingPong()
Start a DMA ping-pong transfer from memory to a peripheral.

DMADRV_PeripheralMemoryPingPong()
Start a DMA ping-pong transfer from a peripheral to memory.

DMADRV_LdmaStartTransfer()
Start a DMA transfer on an LDMA controller.

DMADRV_PauseTransfer()
Pause an ongoing DMA transfer.

DMADRV_ResumeTransfer()
Resume paused DMA transfer.

DMADRV_StopTransfer()
Stop an ongoing DMA transfer.

DMADRV_TransferActive()
Check if a transfer is ongoing.

DMADRV_TransferCompletePending()
Check if a transfer completion is pending.

DMADRV_TransferDone()
Check if a transfer has completed.

DMADRV_TransferRemainingCount()
Get number of items remaining in a transfer.

Example#

Transfer a text string to USART1.

#include "dmadrv.h"

  char str[] = "Hello DMA !";
  unsigned int channel;

  int main( void )
  {
  // Initialize DMA.
  DMADRV_Init();

  // Request a DMA channel.
  DMADRV_AllocateChannel( &channel, NULL );

  // Start the DMA transfer.
  DMADRV_MemoryPeripheral( channel,
                          dmadrvPeripheralSignal_USART1_TXBL,
                          (void*)&(USART1->TXDATA),
                          str,
                          true,
                          sizeof( str ),
                          dmadrvDataSize1,
                          NULL,
                          NULL );

  return 0;
  }
#include "dmadrv.h"

  char str[] = "Hello DMA !";
  unsigned int channel;

  int main( void )
  {
  // Initialize DMA.
  DMADRV_Init();

  // Request a DMA channel.
  DMADRV_AllocateChannel( &channel, NULL );

  // Start the DMA transfer.
  DMADRV_MemoryPeripheral( channel,
                          dmadrvPeripheralSignal_USART1_TXBL,
                          (void*)&(USART1->TXDATA),
                          str,
                          true,
                          sizeof( str ),
                          dmadrvDataSize1,
                          NULL,
                          NULL );

  return 0;
  }

Warnings

• This API is deprecated. For new designs, use the DMA Channel Driver (DMA Channel Driver) and the DMA Manager service (dma_manager).

The DMA driver is used to configure and control the DMA and LDMA peripherals to perform data transfers between memory regions and/or peripherals. It also provides central management of DMA channels and the interrupt vector so that DMA resources could be shared between several users.

These responsibilities are now split between two newer components:

• The dma_manager service owns DMA peripheral initialization, channel/sync-bit allocation, channel prioritization and IRQ dispatch.

• The DMA Channel Driver driver provides the per-channel transfer submission, queuing, ping-pong / triple-buffered transfers and completion notifications.

For the full API mapping table and step-by-step migration instructions, refer to the DMADRV Migration Guide.

Coexistence with DMA Manager and DMA Channel Driver#

DMADRV is fully compatible with the dma_manager service and the DMA Channel Driver driver: an application may keep using DMADRV on some channels while the new components drive other channels in the same application. This is the recommended path for incremental migration.

Be aware that linking both stacks pulls in two largely overlapping DMA implementations, so coexistence comes at a measurable code-size cost. Once migration is complete, remove the DMADRV component to recover the footprint.

Note

• To keep a project building cleanly with -Werror while migration is still in progress, the deprecation warnings emitted for the DMADRV API can be suppressed by defining SL_SUPPRESS_DEPRECATION_WARNINGS_SDK_2026_6 at the project or translation-unit level. This affects only warnings introduced by this deprecation cycle, and is intended as a temporary measure; the DMADRV API will be removed in a future major release.

Modules#

Error Codes