This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the configuration and management of the Direct Memory Access Controller(DMAC) module within the device.

The DMAC can transfer data between memories and peripherals, and thus off-load these tasks from the CPU. The module supports peripheral to peripheral, peripheral to memory, memory to peripheral, and memory to memory transfers.

The following peripheral is used by the DMAC Driver:

DMAC (Direct Memory Access Controller)

The following devices can use this module:

Atmel | SMART SAM D21
Atmel | SMART SAM R21
Atmel | SMART SAM D09/D10/D11
Atmel | SMART SAM L21/L22
Atmel | SMART SAM DA1
Atmel | SMART SAM C20/C21
Atmel | SMART SAM HA1
Atmel | SMART SAM R30
Atmel | SMART SAM R34/R35

The outline of this documentation is as follows:

Prerequisites

There are no prerequisites for this module.

Module Overview

SAM devices with DMAC enables high data transfer rates with minimum CPU intervention and frees up CPU time. With access to all peripherals, the DMAC can handle automatic transfer of data to/from modules. It supports static and incremental addressing for both source and destination.

The DMAC when used with Event System or peripheral triggers, provides a considerable advantage by reducing the power consumption and performing data transfer in the background. For example, if the ADC is configured to generate an event, it can trigger the DMAC to transfer the data into another peripheral or SRAM. The CPU can remain in sleep during this time to reduce the power consumption.

Device	Dma channel number
SAM D21/R21/C20/C21	12
SAM D09/D10/D11	6
SAM L21,SAMR30/R34/R35	16
SAM R34/R35	12

The DMA channel operation can be suspended at any time by software, by events from event system, or after selectable descriptor execution. The operation can be resumed by software or by events from the event system. The DMAC driver for SAM supports four types of transfers such as peripheral to peripheral, peripheral to memory, memory to peripheral, and memory to memory.

The basic transfer unit is a beat, which is defined as a single bus access. There can be multiple beats in a single block transfer and multiple block transfers in a DMA transaction. DMA transfer is based on descriptors, which holds transfer properties such as the source and destination addresses, transfer counter, and other additional transfer control information. The descriptors can be static or linked. When static, a single block transfer is performed. When linked, a number of transfer descriptors can be used to enable multiple block transfers within a single DMA transaction.

The implementation of the DMA driver is based on the idea that the DMA channel is a finite resource of entities with the same abilities. A DMA channel resource is able to move a defined set of data from a source address to destination address triggered by a transfer trigger. On the SAM devices there are 12 DMA resources available for allocation. Each of these DMA resources can trigger interrupt callback routines and peripheral events. The other main features are:

Selectable transfer trigger source
- Software
- Event System
- Peripheral
Event input and output is supported for the four lower channels
Four level channel priority
Optional interrupt generation on transfer complete, channel error, or channel suspend
Supports multi-buffer or circular buffer mode by linking multiple descriptors
Beat size configurable as 8-bit, 16-bit, or 32-bit

A simplified block diagram of the DMA Resource can be seen in the figure below.

Driver Feature Macro Definition

Driver Feature Macro	Supported devices
FEATURE_DMA_CHANNEL_STANDBY	SAM L21/L22/C20/C21/R30/R34/R35

Note: The specific features are only available in the driver when the selected device supports those features.

Terminology Used in DMAC Transfers

Name	Description
Beat	It is a single bus access by the DMAC. Configurable as 8-bit, 16-bit, or 32-bit.
Burst	It is a transfer of n-beats (n=1,4,8,16). For the DMAC module in SAM, the burst size is one beat. Arbitration takes place each time a burst transfer is completed.
Block transfer	A single block transfer is a configurable number of (1 to 64k) beat transfers

DMA Channels

The DMAC in each device consists of several DMA channels, which along with the transfer descriptors defines the data transfer properties.

The transfer control descriptor defines the source and destination addresses, source and destination address increment settings, the block transfer count, and event output condition selection
Dedicated channel registers control the peripheral trigger source, trigger mode settings, event input actions, and channel priority level settings

With a successful DMA resource allocation, a dedicated DMA channel will be assigned. The channel will be occupied until the DMA resource is freed. A DMA resource handle is used to identify the specific DMA resource. When there are multiple channels with active requests, the arbiter prioritizes the channels requesting access to the bus.

DMA Triggers

DMA transfer can be started only when a DMA transfer request is acknowledged/granted by the arbiter. A transfer request can be triggered from software, peripheral, or an event. There are dedicated source trigger selections for each DMA channel usage.

DMA Transfer Descriptor

The transfer descriptor resides in the SRAM and defines these channel properties.

Field name	Field width
Descriptor Next Address	32 bits
Destination Address	32 bits
Source Address	32 bits
Block Transfer Counter	16 bits
Block Transfer Control	16 bits

Before starting a transfer, at least one descriptor should be configured. After a successful allocation of a DMA channel, the transfer descriptor can be added with a call to dma_add_descriptor(). If there is a transfer descriptor already allocated to the DMA resource, the descriptor will be linked to the next descriptor address.

DMA Interrupts/Events

Both an interrupt callback and an peripheral event can be triggered by the DMA transfer. Three types of callbacks are supported by the DMA driver: transfer complete, channel suspend, and transfer error. Each of these callback types can be registered and enabled for each channel independently through the DMA driver API.

The DMAC module can also generate events on transfer complete. Event generation is enabled through the DMA channel, event channel configuration, and event user multiplexing is done through the events driver.

The DMAC can generate events in the below cases:

When a block transfer is complete
When each beat transfer within a block transfer is complete

Special Considerations

There are no special considerations for this module.

Extra Information

For extra information, see Extra Information for DMAC Driver. This includes:

Examples

For a list of examples related to this driver, see Examples for DMAC Driver.

API Overview

Data Structures
struct	dma_descriptor_config
	DMA transfer descriptor configuration. More...

struct	dma_events_config
	Configurations for DMA events. More...

struct	dma_resource
	Structure for DMA transfer resource. More...

struct	dma_resource_config
	DMA configurations for transfer. More...

Macros
#define	DMA_INVALID_CHANNEL 0xff
	DMA invalid channel number. More...

Typedefs
typedef void(*	dma_callback_t )(struct dma_resource *const resource)
	Type definition for a DMA resource callback function. More...

Enumerations
enum	dma_address_increment_stepsize { DMA_ADDRESS_INCREMENT_STEP_SIZE_1 = 0, DMA_ADDRESS_INCREMENT_STEP_SIZE_2, DMA_ADDRESS_INCREMENT_STEP_SIZE_4, DMA_ADDRESS_INCREMENT_STEP_SIZE_8, DMA_ADDRESS_INCREMENT_STEP_SIZE_16, DMA_ADDRESS_INCREMENT_STEP_SIZE_32, DMA_ADDRESS_INCREMENT_STEP_SIZE_64, DMA_ADDRESS_INCREMENT_STEP_SIZE_128 }
	Address increment step size. More...

enum	dma_beat_size { DMA_BEAT_SIZE_BYTE = 0, DMA_BEAT_SIZE_HWORD, DMA_BEAT_SIZE_WORD }
	The basic transfer unit in DMAC is a beat, which is defined as a single bus access. More...

enum	dma_block_action { DMA_BLOCK_ACTION_NOACT = 0, DMA_BLOCK_ACTION_INT, DMA_BLOCK_ACTION_SUSPEND, DMA_BLOCK_ACTION_BOTH }
	Block action definitions. More...

enum	dma_callback_type { DMA_CALLBACK_TRANSFER_ERROR, DMA_CALLBACK_TRANSFER_DONE, DMA_CALLBACK_CHANNEL_SUSPEND, DMA_CALLBACK_N }
	Callback types for DMA callback driver. More...

enum	dma_event_input_action { DMA_EVENT_INPUT_NOACT, DMA_EVENT_INPUT_TRIG, DMA_EVENT_INPUT_CTRIG, DMA_EVENT_INPUT_CBLOCK, DMA_EVENT_INPUT_SUSPEND, DMA_EVENT_INPUT_RESUME, DMA_EVENT_INPUT_SSKIP }
	DMA input actions. More...

enum	dma_event_output_selection { DMA_EVENT_OUTPUT_DISABLE = 0, DMA_EVENT_OUTPUT_BLOCK, DMA_EVENT_OUTPUT_RESERVED, DMA_EVENT_OUTPUT_BEAT }
	Event output selection. More...

enum	dma_priority_level { DMA_PRIORITY_LEVEL_0, DMA_PRIORITY_LEVEL_1, DMA_PRIORITY_LEVEL_2, DMA_PRIORITY_LEVEL_3 }
	DMA priority level. More...

enum	dma_step_selection { DMA_STEPSEL_DST = 0, DMA_STEPSEL_SRC }
	DMA step selection. More...

enum	dma_transfer_trigger_action { DMA_TRIGGER_ACTION_BLOCK = DMAC_CHCTRLB_TRIGACT_BLOCK_Val, DMA_TRIGGER_ACTION_BEAT = DMAC_CHCTRLB_TRIGACT_BEAT_Val, DMA_TRIGGER_ACTION_TRANSACTION = DMAC_CHCTRLB_TRIGACT_TRANSACTION_Val }
	DMA trigger action type. More...

Functions
void	dma_abort_job (struct dma_resource *resource)
	Abort a DMA transfer. More...

enum status_code	dma_add_descriptor (struct dma_resource resource, DmacDescriptor descriptor)
	Add a DMA transfer descriptor to a DMA resource. More...

enum status_code	dma_allocate (struct dma_resource resource, struct dma_resource_config config)
	Allocate a DMA with configurations. More...

void	dma_descriptor_create (DmacDescriptor descriptor, struct dma_descriptor_config config)
	Create a DMA transfer descriptor with configurations. More...

static void	dma_descriptor_get_config_defaults (struct dma_descriptor_config *config)
	Initializes DMA transfer configuration with predefined default values. More...

static void	dma_disable_callback (struct dma_resource *resource, enum dma_callback_type type)
	Disable a callback function for a dedicated DMA resource. More...

static void	dma_enable_callback (struct dma_resource *resource, enum dma_callback_type type)
	Enable a callback function for a dedicated DMA resource. More...

enum status_code	dma_free (struct dma_resource *resource)
	Free an allocated DMA resource. More...

void	dma_get_config_defaults (struct dma_resource_config *config)
	Initializes config with predefined default values. More...

static enum status_code	dma_get_job_status (struct dma_resource *resource)
	Get DMA resource status. More...

static bool	dma_is_busy (struct dma_resource *resource)
	Check if the given DMA resource is busy. More...

static void	dma_register_callback (struct dma_resource *resource, dma_callback_t callback, enum dma_callback_type type)
	Register a callback function for a dedicated DMA resource. More...

static void	dma_reset_descriptor (struct dma_resource *resource)
	Reset DMA descriptor. More...

void	dma_resume_job (struct dma_resource *resource)
	Resume a suspended DMA transfer. More...

enum status_code	dma_start_transfer_job (struct dma_resource *resource)
	Start a DMA transfer. More...

void	dma_suspend_job (struct dma_resource *resource)
	Suspend a DMA transfer. More...

static void	dma_trigger_transfer (struct dma_resource *resource)
	Will set a software trigger for resource. More...

static void	dma_unregister_callback (struct dma_resource *resource, enum dma_callback_type type)
	Unregister a callback function for a dedicated DMA resource. More...

static void	dma_update_descriptor (struct dma_resource resource, DmacDescriptor descriptor)
	Update DMA descriptor. More...

Variables
DmacDescriptor	descriptor_section [CONF_MAX_USED_CHANNEL_NUM]
	ExInitial description section. More...

uint8_t	g_chan_interrupt_flag [CONF_MAX_USED_CHANNEL_NUM]

#define DMA_INVALID_CHANNEL 0xff

DMA invalid channel number.

Referenced by _dma_find_first_free_channel_and_allocate(), dma_abort_job(), dma_allocate(), dma_free(), dma_resume_job(), dma_start_transfer_job(), and dma_suspend_job().

typedef void(* dma_callback_t)(struct dma_resource *const resource)

Type definition for a DMA resource callback function.

enum dma_address_increment_stepsize

Address increment step size.

These bits select the address increment step size. The setting apply to source or destination address, depending on STEPSEL setting.

Enumerator
DMA_ADDRESS_INCREMENT_STEP_SIZE_1	The address is incremented by (beat size * 1).
DMA_ADDRESS_INCREMENT_STEP_SIZE_2	The address is incremented by (beat size * 2).
DMA_ADDRESS_INCREMENT_STEP_SIZE_4	The address is incremented by (beat size * 4).
DMA_ADDRESS_INCREMENT_STEP_SIZE_8	The address is incremented by (beat size * 8).
DMA_ADDRESS_INCREMENT_STEP_SIZE_16	The address is incremented by (beat size * 16).
DMA_ADDRESS_INCREMENT_STEP_SIZE_32	The address is incremented by (beat size * 32).
DMA_ADDRESS_INCREMENT_STEP_SIZE_64	The address is incremented by (beat size * 64).
DMA_ADDRESS_INCREMENT_STEP_SIZE_128	The address is incremented by (beat size * 128).

enum dma_beat_size

The basic transfer unit in DMAC is a beat, which is defined as a single bus access.

Its size is configurable and applies to both read and write.

Enumerator
DMA_BEAT_SIZE_BYTE	8-bit access.
DMA_BEAT_SIZE_HWORD	16-bit access.
DMA_BEAT_SIZE_WORD	32-bit access.

enum dma_block_action

Block action definitions.

Enumerator
DMA_BLOCK_ACTION_NOACT	No action.
DMA_BLOCK_ACTION_INT	Channel in normal operation and sets transfer complete interrupt flag after block transfer.
DMA_BLOCK_ACTION_SUSPEND	Trigger channel suspend after block transfer and sets channel suspend interrupt flag once the channel is suspended.
DMA_BLOCK_ACTION_BOTH	Sets transfer complete interrupt flag after a block transfer and trigger channel suspend. The channel suspend interrupt flag will be set once the channel is suspended.

enum dma_callback_type

Callback types for DMA callback driver.

Enumerator
DMA_CALLBACK_TRANSFER_ERROR	Callback for any of transfer errors. A transfer error is flagged if a bus error is detected during an AHB access or when the DMAC fetches an invalid descriptor.
DMA_CALLBACK_TRANSFER_DONE	Callback for transfer complete.
DMA_CALLBACK_CHANNEL_SUSPEND	Callback for channel suspend.
DMA_CALLBACK_N	Number of available callbacks.

enum dma_event_input_action

DMA input actions.

Enumerator
DMA_EVENT_INPUT_NOACT	No action.
DMA_EVENT_INPUT_TRIG	Normal transfer and periodic transfer trigger.
DMA_EVENT_INPUT_CTRIG	Conditional transfer trigger.
DMA_EVENT_INPUT_CBLOCK	Conditional block transfer.
DMA_EVENT_INPUT_SUSPEND	Channel suspend operation.
DMA_EVENT_INPUT_RESUME	Channel resume operation.
DMA_EVENT_INPUT_SSKIP	Skip next block suspend action.

enum dma_event_output_selection

Event output selection.

Enumerator
DMA_EVENT_OUTPUT_DISABLE	Event generation disable.
DMA_EVENT_OUTPUT_BLOCK	Event strobe when block transfer complete.
DMA_EVENT_OUTPUT_RESERVED	Event output reserved.
DMA_EVENT_OUTPUT_BEAT	Event strobe when beat transfer complete.

enum dma_priority_level

DMA priority level.

Enumerator
DMA_PRIORITY_LEVEL_0	Priority level 0.
DMA_PRIORITY_LEVEL_1	Priority level 1.
DMA_PRIORITY_LEVEL_2	Priority level 2.
DMA_PRIORITY_LEVEL_3	Priority level 3.

enum dma_step_selection

DMA step selection.

This bit determines whether the step size setting is applied to source or destination address.

Enumerator
DMA_STEPSEL_DST	Step size settings apply to the destination address.
DMA_STEPSEL_SRC	Step size settings apply to the source address.

enum dma_transfer_trigger_action

DMA trigger action type.

Enumerator
DMA_TRIGGER_ACTION_BLOCK	Perform a block transfer when triggered.
DMA_TRIGGER_ACTION_BEAT	Perform a beat transfer when triggered.
DMA_TRIGGER_ACTION_TRANSACTION	Perform a transaction when triggered.

void dma_abort_job ( struct dma_resource * resource )

Abort a DMA transfer.

This function will abort a DMA transfer. The DMA channel used for the DMA resource will be disabled. The block transfer count will also be calculated and written to the DMA resource structure.

Note: The DMA resource will not be freed after calling this function. The function dma_free() can be used to free an allocated resource.

Parameters

[in,out] resource Pointer to the DMA resource

References Assert, dma_resource::channel_id, descriptor_section, DMA_INVALID_CHANNEL, dma_resource::job_status, STATUS_ABORTED, system_interrupt_enter_critical_section(), system_interrupt_leave_critical_section(), and dma_resource::transfered_size.

enum status_code dma_add_descriptor	(	struct dma_resource *	resource,
		DmacDescriptor *	descriptor
	)

Add a DMA transfer descriptor to a DMA resource.

This function will add a DMA transfer descriptor to a DMA resource. If there was a transfer descriptor already allocated to the DMA resource, the descriptor will be linked to the next descriptor address.

Parameters

[in]	resource	Pointer to the DMA resource
[in]	descriptor	Pointer to the transfer descriptor

Return values

STATUS_OK	The descriptor is added to the DMA resource
STATUS_BUSY	The DMA resource was busy and the descriptor is not added

References dma_resource::descriptor, dma_resource::job_status, STATUS_BUSY, and STATUS_OK.

enum status_code dma_allocate	(	struct dma_resource *	resource,
		struct dma_resource_config *	config
	)

Allocate a DMA with configurations.

This function will allocate a proper channel for a DMA transfer request.

Parameters

[in,out]	dma_resource	Pointer to a DMA resource instance
[in]	transfer_config	Configurations of the DMA transfer

Returns: Status of the allocation procedure.

Return values

STATUS_OK	The DMA resource was allocated successfully
STATUS_ERR_NOT_FOUND	DMA resource allocation failed

Perform a reset for the allocated channel

Configure the DMA control,channel registers and descriptors here

References _dma_active_resource, _dma_find_first_free_channel_and_allocate(), _dma_module::_dma_init, _dma_set_config(), Assert, dma_resource::channel_id, dma_resource::descriptor, descriptor_section, DMA_INVALID_CHANNEL, STATUS_ERR_NOT_FOUND, STATUS_OK, system_ahb_clock_set_mask(), system_apb_clock_set_mask(), SYSTEM_CLOCK_APB_APBB, system_interrupt_enter_critical_section(), and system_interrupt_leave_critical_section().

void dma_descriptor_create	(	DmacDescriptor *	descriptor,
		struct dma_descriptor_config *	config
	)

Create a DMA transfer descriptor with configurations.

This function will set the transfer configurations to the DMA transfer descriptor.

Parameters

[in]	descriptor	Pointer to the DMA transfer descriptor
[in]	config	Pointer to the descriptor configuration structure

static void dma_descriptor_get_config_defaults ( struct dma_descriptor_config * config )

inlinestatic

Initializes DMA transfer configuration with predefined default values.

This function will initialize a given DMA descriptor configuration structure to a set of known default values. This function should be called on any new instance of the configuration structure before being modified by the user application.

The default configuration is as follows:

Set the descriptor as valid
Disable event output
No block action
Set beat size as byte
Enable source increment
Enable destination increment
Step size is applied to the destination address
Address increment is beat size multiplied by 1
Default transfer size is set to 0
Default source address is set to NULL
Default destination address is set to NULL
Default next descriptor not available
Parameters

[out] config Pointer to the configuration

Next descriptor address set to 0

static void dma_disable_callback	(	struct dma_resource *	resource,
		enum dma_callback_type	type
	)

inlinestatic

Disable a callback function for a dedicated DMA resource.

Parameters

[in]	resource	Pointer to the DMA resource
[in]	type	Callback function type

References Assert, dma_resource::callback_enable, and dma_resource::channel_id.

static void dma_enable_callback	(	struct dma_resource *	resource,
		enum dma_callback_type	type
	)

inlinestatic

Enable a callback function for a dedicated DMA resource.

Parameters

[in]	resource	Pointer to the DMA resource
[in]	type	Callback function type

References Assert, dma_resource::callback_enable, and dma_resource::channel_id.

enum status_code dma_free ( struct dma_resource * resource )

Free an allocated DMA resource.

This function will free an allocated DMA resource.

Parameters

[in,out] resource Pointer to the DMA resource

Returns: Status of the free procedure.

Return values

STATUS_OK	The DMA resource was freed successfully
STATUS_BUSY	The DMA resource was busy and can't be freed
STATUS_ERR_NOT_INITIALIZED	DMA resource was not initialized

References _dma_active_resource, _dma_release_channel(), _dma_module::allocated_channels, Assert, dma_resource::channel_id, DMA_INVALID_CHANNEL, dma_is_busy(), STATUS_BUSY, STATUS_ERR_NOT_INITIALIZED, STATUS_OK, system_interrupt_enter_critical_section(), and system_interrupt_leave_critical_section().

void dma_get_config_defaults ( struct dma_resource_config * config )

Initializes config with predefined default values.

This function will initialize a given DMA configuration structure to a set of known default values. This function should be called on any new instance of the configuration structure before being modified by the user application.

The default configuration is as follows:

Software trigger is used as the transfer trigger
Priority level 0
Only software/event trigger
Requires a trigger for each transaction
No event input /output
DMA channel is disabled during sleep mode (if has the feature)
Parameters

[out] config Pointer to the configuration

References Assert, DMA_EVENT_INPUT_NOACT, DMA_PRIORITY_LEVEL_0, DMA_TRIGGER_ACTION_TRANSACTION, dma_resource_config::event_config, dma_events_config::event_output_enable, dma_events_config::input_action, dma_resource_config::peripheral_trigger, dma_resource_config::priority, and dma_resource_config::trigger_action.

static enum status_code dma_get_job_status ( struct dma_resource * resource )

inlinestatic

Get DMA resource status.

Parameters

[in] resource Pointer to the DMA resource

Returns: Status of the DMA resource.

References Assert, and dma_resource::job_status.

static bool dma_is_busy ( struct dma_resource * resource )

inlinestatic

Check if the given DMA resource is busy.

Parameters

[in] resource Pointer to the DMA resource

Returns: Status which indicates whether the DMA resource is busy.

Return values

true	The DMA resource has an on-going transfer
false	The DMA resource is not busy

References Assert, dma_resource::job_status, and STATUS_BUSY.

Referenced by dma_free().

static void dma_register_callback	(	struct dma_resource *	resource,
		dma_callback_t	callback,
		enum dma_callback_type	type
	)

inlinestatic

Register a callback function for a dedicated DMA resource.

There are three types of callback functions, which can be registered:

Callback for transfer complete
Callback for transfer error
Callback for channel suspend

Parameters

[in]	resource	Pointer to the DMA resource
[in]	callback	Pointer to the callback function
[in]	type	Callback function type

References Assert, and dma_resource::callback.

static void dma_reset_descriptor ( struct dma_resource * resource )

inlinestatic

Reset DMA descriptor.

This function will clear the DESCADDR register of an allocated DMA resource.

References Assert, and dma_resource::descriptor.

void dma_resume_job ( struct dma_resource * resource )

Resume a suspended DMA transfer.

This function try to resume a suspended transfer of a DMA resource.

Parameters

[in] resource Pointer to the DMA resource

References Assert, dma_resource::channel_id, DMA_INVALID_CHANNEL, dma_resource::job_status, MAX_JOB_RESUME_COUNT, STATUS_BUSY, STATUS_ERR_TIMEOUT, STATUS_SUSPEND, system_interrupt_enter_critical_section(), and system_interrupt_leave_critical_section().

enum status_code dma_start_transfer_job ( struct dma_resource * resource )

Start a DMA transfer.

This function will start a DMA transfer through an allocated DMA resource.

Parameters

[in,out] resource Pointer to the DMA resource

Returns: Status of the transfer start procedure.

Return values

STATUS_OK	The transfer was started successfully
STATUS_BUSY	The DMA resource was busy and the transfer was not started
STATUS_ERR_INVALID_ARG	Transfer size is 0 and transfer was not started

References Assert, dma_resource::channel_id, dma_resource::descriptor, descriptor_section, DMA_INVALID_CHANNEL, g_chan_interrupt_flag, dma_resource::job_status, STATUS_BUSY, STATUS_ERR_INVALID_ARG, STATUS_OK, system_interrupt_enable(), system_interrupt_enter_critical_section(), system_interrupt_leave_critical_section(), and SYSTEM_INTERRUPT_MODULE_DMA.

void dma_suspend_job ( struct dma_resource * resource )

Suspend a DMA transfer.

This function will request to suspend the transfer of the DMA resource. The channel is kept enabled, can receive transfer triggers (the transfer pending bit will be set), but will be removed from the arbitration scheme. The channel operation can be resumed by calling dma_resume_job().

Note: This function sets the command to suspend the DMA channel associated with a DMA resource. The channel suspend interrupt flag indicates whether the transfer is truly suspended.

Parameters

[in] resource Pointer to the DMA resource

References Assert, dma_resource::channel_id, DMA_INVALID_CHANNEL, system_interrupt_enter_critical_section(), and system_interrupt_leave_critical_section().

static void dma_trigger_transfer ( struct dma_resource * resource )

inlinestatic

Will set a software trigger for resource.

This function is used to set a software trigger on the DMA channel associated with resource. If a trigger is already pending no new trigger will be generated for the channel.

Parameters

[in] resource Pointer to the DMA resource

References Assert, and dma_resource::channel_id.

static void dma_unregister_callback	(	struct dma_resource *	resource,
		enum dma_callback_type	type
	)

inlinestatic

Unregister a callback function for a dedicated DMA resource.

There are three types of callback functions:

Callback for transfer complete
Callback for transfer error
Callback for channel suspend

The application can unregister any of the callback functions which are already registered and are no longer needed.

Parameters

[in]	resource	Pointer to the DMA resource
[in]	type	Callback function type

References Assert, and dma_resource::callback.

static void dma_update_descriptor	(	struct dma_resource *	resource,
		DmacDescriptor *	descriptor
	)

inlinestatic

Update DMA descriptor.

This function can update the descriptor of an allocated DMA resource.

References Assert, and dma_resource::descriptor.

DmacDescriptor descriptor_section[CONF_MAX_USED_CHANNEL_NUM]

ExInitial description section.

Referenced by dma_abort_job(), dma_allocate(), dma_start_transfer_job(), and DMAC_Handler().

uint8_t g_chan_interrupt_flag[CONF_MAX_USED_CHANNEL_NUM]

Referenced by dma_start_transfer_job().

Microchip® Advanced Software Framework

Prerequisites

Module Overview

Driver Feature Macro Definition

Terminology Used in DMAC Transfers

DMA Channels

DMA Triggers

DMA Transfer Descriptor

DMA Interrupts/Events

Special Considerations

Extra Information

Examples

API Overview

Data Structures

Macros

Typedefs

Enumerations

Functions

Variables