DMA - Direct Memory Access#

DMA_DataInc_TypeDef#

DMA_DataInc_TypeDef

Amount source/destination address should be incremented for each data transfer.

DMA_DataSize_TypeDef#

DMA_DataSize_TypeDef

Data sizes (in number of bytes) to be read/written by DMA transfer.

DMA_CycleCtrl_TypeDef#

DMA_CycleCtrl_TypeDef

Types of DMA transfer.

DMA_ArbiterConfig_TypeDef#

DMA_ArbiterConfig_TypeDef

Number of transfers before controller does new arbitration.

DMA_FuncPtr_TypeDef#

typedef void(* DMA_FuncPtr_TypeDef) (unsigned int channel, bool primary, void *user) )(unsigned int channel, bool primary, void *user)

DMA interrupt callback function pointer.

Parameters:

• channel - DMA channel the callback function is invoked for.

• primary - Indicates if callback is invoked for completion of primary (true) or alternate (false) descriptor. Mainly useful for ping-pong DMA cycles, to know which descriptor to refresh.

• user - User definable reference that may be used to pass information to be used by the callback handler. If used, referenced data must be valid at the point when the interrupt handler invokes callback. If callback changes any data in the provided user structure, remember that those changes are done in interrupt context and proper protection of data may be required.

DMA_IRQHandler#

void DMA_IRQHandler (void )

Interrupt handler for the DMA cycle completion handling.

Clears any pending flags and calls registered callback (if any).

If using the default interrupt vector table setup provided, this function is automatically placed in the IRQ table due to weak linking. If taking control over the interrupt vector table in some other way, this interrupt handler must be installed to support callback actions.

For the user to implement a custom IRQ handler or run without a DMA IRQ handler, define EXCLUDE_DEFAULT_DMA_IRQ_HANDLER with a #define statement or with the compiler option -D.

DMA_ActivateAuto#

void DMA_ActivateAuto (unsigned int channel, bool primary, void * dst, const void * src, unsigned int nMinus1)

Activate the DMA auto-request cycle (used for memory-memory transfers).

Prior to activating the DMA cycle, the channel and descriptor to be used must have been properly configured.

Note

• If using this function on a channel already activated and in use by the DMA controller, the behavior is undefined.

DMA_ActivateBasic#

void DMA_ActivateBasic (unsigned int channel, bool primary, bool useBurst, void * dst, const void * src, unsigned int nMinus1)

Activate the DMA basic cycle (used for memory-peripheral transfers).

Prior to activating the DMA cycle, the channel and descriptor to be used must have been properly configured.

Note

• If using this function on a channel already activated and in use by the DMA controller, the behavior is undefined.

DMA_ActivatePingPong#

void DMA_ActivatePingPong (unsigned int channel, bool useBurst, void * primDst, const void * primSrc, unsigned int primNMinus1, void * altDst, const void * altSrc, unsigned int altNMinus1)

Activate a DMA ping-pong cycle (used for memory-peripheral transfers).

Prior to activating the DMA cycle, the channel and both descriptors must have been properly configured. The primary descriptor is always the first descriptor to be used by the DMA controller.

Note

• If using this function on a channel already activated and in use by the DMA controller, the behavior is undefined.

DMA_ActivateScatterGather#

void DMA_ActivateScatterGather (unsigned int channel, bool useBurst, DMA_DESCRIPTOR_TypeDef * altDescr, unsigned int count)

Activate the DMA scatter-gather cycle (used for either memory-peripheral or memory-memory transfers).

Prior to activating the DMA cycle, the array with alternate descriptors must have been properly configured. This function can be reused without reconfiguring the alternate descriptors, as long as count is the same.

Note

• If using this function on a channel already activated and in use by the DMA controller, the behavior is undefined.

DMA_CfgChannel#

void DMA_CfgChannel (unsigned int channel, DMA_CfgChannel_TypeDef * cfg)

Configure a DMA channel.

Configure miscellaneous issues for a DMA channel. This function is typically used once to set up a channel for a certain type of use.

Note

• If using this function on a channel already in use by the DMA controller, the behavior is undefined.

DMA_CfgDescr#

void DMA_CfgDescr (unsigned int channel, bool primary, DMA_CfgDescr_TypeDef * cfg)

Configure the DMA descriptor for auto-request, basic, or ping-pong DMA cycles.

This function is used to configure a descriptor for the following DMA cycle types:

• auto-request - used for a memory/memory transfer

• basic - used for a peripheral/memory transfer

• ping-pong - used for a ping-pong-based peripheral/memory transfer style providing time to refresh one descriptor while the other is in use.

The DMA cycle is not activated. See DMA_ActivateAuto(), DMA_ActivateBasic(), or DMA_ActivatePingPong() to activate the DMA cycle. In many cases, the configuration only has to be done once, and all subsequent cycles may be activated with the activate function.

For ping-pong DMA cycles, this function must be used both on the primary and the alternate descriptor prior to activating the DMA cycle.

Notice that the DMA channel must also be configured. See DMA_CfgChannel().

Note

• If using this function on a descriptor already activated and in use by the DMA controller, the behavior is undefined.

DMA_CfgDescrScatterGather#

void DMA_CfgDescrScatterGather (DMA_DESCRIPTOR_TypeDef * descr, unsigned int indx, DMA_CfgDescrSGAlt_TypeDef * cfg)

Configure an alternate DMA descriptor for use with scatter-gather DMA cycles.

In scatter-gather mode, the alternate descriptors are located in one contiguous memory area. Each of the alternate descriptors must be fully configured prior to starting the scatter-gather DMA cycle.

The DMA cycle is not activated by this function. See DMA_ActivateScatterGather() to activate the DMA cycle. In some cases, the alternate configuration only has to be done once and all subsequent transfers may be activated with the activate function.

Notice that the DMA channel must also be configured, see DMA_CfgChannel().

DMA_ChannelEnable#

void DMA_ChannelEnable (unsigned int channel, bool enable)

Enable or disable a DMA channel.

Use this function to explicitly enable or disable a DMA channel. A DMA channel is automatically disabled when the DMA controller has finished a transaction.

DMA_ChannelEnabled#

bool DMA_ChannelEnabled (unsigned int channel)

Check if the DMA channel is enabled.

The DMA channel is disabled when the DMA controller has finished a DMA cycle.

Returns

• True if the channel is enabled, false if not.

DMA_ChannelRequestEnable#

void DMA_ChannelRequestEnable (unsigned int channel, bool enable)

Enable or disable a DMA channel request.

Use this function to enable or disable a DMA channel request. This will prevent the DMA from proceeding after its current transaction if disabled.

DMA_Init#

void DMA_Init (DMA_Init_TypeDef * init)

Initialize the DMA controller.

This function resets and prepares the DMA controller for use. Although it may be used several times, it is normally only used during system initialization. If reused during a normal operation, any ongoing DMA transfers will be aborted. When complete, the DMA controller is in an enabled state.

Note

• Must be invoked before using the DMA controller.

DMA_RefreshPingPong#

void DMA_RefreshPingPong (unsigned int channel, bool primary, bool useBurst, void * dst, const void * src, unsigned int nMinus1, bool stop)

Refresh a descriptor used in a DMA ping-pong cycle.

During a ping-pong DMA cycle, the DMA controller automatically alternates between the primary and alternate descriptors, when completing use of a descriptor. While the other descriptor is in use by the DMA controller, the software should refresh the completed descriptor. This is typically done from the callback defined for the ping-pong cycle.

DMA_Reset#

void DMA_Reset (void )

Reset the DMA controller.

This functions will disable the DMA controller and set it to a reset state.

Note

• Note that any ongoing transfers will be aborted.

DMA_IntClear#

void DMA_IntClear (uint32_t flags)

Clear one or more pending DMA interrupts.

DMA_IntDisable#

void DMA_IntDisable (uint32_t flags)

Disable one or more DMA interrupts.

DMA_IntEnable#

void DMA_IntEnable (uint32_t flags)

Enable one or more DMA interrupts.

Note

• Depending on the use, a pending interrupt may already be set prior to enabling the interrupt. To ignore a pending interrupt, consider using DMA_IntClear() prior to enabling the interrupt.

DMA_IntGet#

uint32_t DMA_IntGet (void )

Get pending DMA interrupt flags.

Note

• Event bits are not cleared by the use of this function.

Returns

• DMA interrupt sources pending. Returns one or more valid interrupt flags for the DMA module (DMA_IF_nnn).

DMA_IntGetEnabled#

uint32_t DMA_IntGetEnabled (void )

Get enabled and pending DMA interrupt flags.

Useful for handling more interrupt sources in the same interrupt handler.

Note

• Interrupt flags are not cleared by the use of this function.

Returns

• Pending and enabled DMA interrupt sources Return value is the bitwise AND of

  • the enabled interrupt sources in DMA_IEN and

  • the pending interrupt flags DMA_IF.

DMA_IntSet#

void DMA_IntSet (uint32_t flags)

Set one or more pending DMA interrupts.