This driver for Atmel® | SMART ARM®-based microcontrollers provides an interface for the conversion of digital values to analog voltage.

The following driver API modes are covered by this manual:

Polled APIs

The following peripheral is used by this module:

DAC (Digital-to-Analog Converter)

The following devices can use this module:

Atmel | SMART SAM L21

The outline of this documentation is as follows:

Prerequisites

There are no prerequisites for this module.

Module Overview

The Digital-to-Analog converter converts a digital value to an analog voltage. The DAC Controller can operate as two independent DACs or as a single DAC in differential mode. Each DAC has a 12-bit resolution and it is capable of converting up to 1M samples per second (Msps).

A common use of DAC is to generate audio signals by connecting the DAC output to a speaker, or to generate a reference voltage; either for an external circuit or an internal peripheral such as the Analog Comparator.

After being set up, the DAC will convert new digital values written to the conversion data register (DATA0 or DATA1) to an analog value either on the DAC output (VOUT0 or VOUT1) pin of the device, or internally for use as an input to the AC, ADC, and other analog modules.

Writing the DATA register will start a new conversion. It is also possible to trigger the conversion from the event system.

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

DAC Block Diagram

Conversion Range

The conversion range is between GND and the selected voltage reference. Available voltage references are:

Voltage supply (VDDANA)
Internal bandgap reference (INTREF)
Unbuffered External voltage reference (VREFPU)
Buffered External voltage reference (VREFPB)

Note: Internal references will be enabled by the driver, but not disabled. Any reference not used by the application should be disabled by the application.

The output voltage from a DAC channel is given as:

\[ V_{OUTx} = \frac{DATAx}{0x3FF} \times VREF \]

The differential output voltage is given as:

\[ V_{OUT} = \frac{DATA0}{0x1FF} \times VREF = (V_{OUT0}-V_{OUT1}) \]

Conversion

The conversion digital value written to the DATA register will be converted to an analog value. Writing the DATA register will start a new conversion. It is also possible to write the conversion value to the DATABUF register, the writing of the DATA register can then be triggered from the event system, which will load the value from DATABUF to DATA.

Analog Output

The analog output value can be output to the VOUTx converted by DACx, and each data conversion can be started independently.

In differential mode, DAC0 and DAC1 are operating synchronously to convert value. VOUT0 is the positive output and VOUT1 the negative output.

VOUT0 signal is internally connected so that it can be used as input for AC, ADC, or OPAMP modules when DAC0 is enabled.

Note: The pin VOUT0 will be dedicated to internal input and cannot be configured as alternate function.

Events

Events generation and event actions are configurable in the DAC. The DAC has one event line input and one event output: Start Conversion and Data Buffer Empty.

If the Start Conversion input event is enabled in the module configuration, an incoming event will load data from the data buffer to the data register and start a new conversion. This method synchronizes conversions with external events (such as those from a timer module) and ensures regular and fixed conversion intervals.

If the Data Buffer Empty output event is enabled in the module configuration, events will be generated when the DAC data buffer register becomes empty and new data can be loaded to the buffer.

Note: The connection of events between modules requires the use of the SAM Event System Driver (EVENTS) to route output event of one module to the the input event of another. For more information on event routing, refer to the event driver documentation.

Left and Right Adjusted Values

The 12-bit input value to the DAC is contained in a 16-bit register. This can be configured to be either left or right adjusted. In the figure below both options are shown, and the position of the most (MSB) and the least (LSB) significant bits are indicated. The unused bits should always be written to zero.

Clock Sources

The clock for the DAC interface (CLK_DAC) is generated by the Power Manager. This clock is turned on by default, and can be enabled and disabled in the Power Manager.

Additionally, an asynchronous clock source (GCLK_DAC) is required. These clocks are normally disabled by default. The selected clock source must be enabled in the Power Manager before it can be used by the DAC. The DAC core operates asynchronously from the user interface and peripheral bus. As a consequence, the DAC needs two clock cycles of both CLK_DAC and GCLK_DAC to synchronize the values written to some of the control and data registers. The oscillator source for the GCLK_DAC clock is selected in the Supply Control Interface (SUPC).

Special Considerations

Sleep Mode

The DAC can do conversions in Active or Idle modes, and will continue the conversions in standby sleep mode if the RUNSTDBY bit in the DACCTRLx register is set. Otherwise, the DACx will stop conversions.

If DACx conversion is stopped in standby sleep mode, DACx is disabled to reduce power consumption. When exiting standby sleep mode, DACx is enabled therefore startup time is required before starting a new conversion.

Conversion Time

DAC conversion time is approximately 2.85µs. The user must ensure that new data is not written to the DAC before the last conversion is complete. Conversions should be triggered by a periodic event from a Timer/Counter or another peripheral.

Extra Information

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

Examples

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

API Overview

Data Structures
struct	dac_chan_config
	DAC channel configuration structure. More...

struct	dac_config
	DAC configuration structure. More...

struct	dac_events
	DAC event enable/disable structure. More...

struct	dac_module
	DAC software device instance structure. More...

Macros
#define	DAC_TIMEOUT 0xFFFF
	Define DAC features set according to different device families. More...

Typedefs
typedef void(*	dac_callback_t )(uint8_t channel)
	Type definition for a DAC module callback function. More...

Enumerations
enum	dac_callback { DAC_CALLBACK_DATA_EMPTY, DAC_CALLBACK_DATA_UNDERRUN, DAC_CALLBACK_TRANSFER_COMPLETE }
	Enum for the possible callback types for the DAC module. More...

enum	dac_channel { DAC_CHANNEL_0, DAC_CHANNEL_1 }
	DAC channel selection enum. More...

enum	dac_current_ctrl { DAC_CURRENT_100K = DAC_DACCTRL_CCTRL(0), DAC_CURRENT_1M = DAC_DACCTRL_CCTRL(1), DAC_CURRENT_12M = DAC_DACCTRL_CCTRL(2), DAC_CURRENT_RESERVED = DAC_DACCTRL_CCTRL(3) }
	DAC current control enum. More...

enum	dac_reference { DAC_REFERENCE_VREFPU = DAC_CTRLB_REFSEL(0), DAC_REFERENCE_VDDANA = DAC_CTRLB_REFSEL(1), DAC_REFERENCE_VREFPB = DAC_CTRLB_REFSEL(2), DAC_REFERENCE_INTREF = DAC_CTRLB_REFSEL(3) }
	DAC reference voltage enum. More...

Configuration and Initialization
bool	dac_is_syncing (struct dac_module *const dev_inst)
	Determines if the hardware module(s) are currently synchronizing to the bus. More...

void	dac_get_config_defaults (struct dac_config *const config)
	Initializes a DAC configuration structure to defaults. More...

enum status_code	dac_init (struct dac_module const dev_inst, Dac const module, struct dac_config *const config)
	Initialize the DAC device struct. More...

void	dac_reset (struct dac_module *const dev_inst)
	Resets the DAC module. More...

void	dac_enable (struct dac_module *const dev_inst)
	Enable the DAC module. More...

void	dac_disable (struct dac_module *const dev_inst)
	Disable the DAC module. More...

void	dac_enable_events (struct dac_module const module_inst, struct dac_events const events)
	Enables a DAC event input or output. More...

void	dac_disable_events (struct dac_module const module_inst, struct dac_events const events)
	Disables a DAC event input or output. More...

Configuration and Initialization (Channel)
void	dac_chan_get_config_defaults (struct dac_chan_config *const config)

void	dac_chan_set_config (struct dac_module const dev_inst, const enum dac_channel channel, struct dac_chan_config const config)
	Writes a DAC channel configuration to the hardware module. More...

void	dac_chan_enable (struct dac_module *const dev_inst, enum dac_channel channel)
	Enable a DAC channel. More...

void	dac_chan_disable (struct dac_module *const dev_inst, enum dac_channel channel)
	Disable a DAC channel. More...

Channel Data Management
enum status_code	dac_chan_write (struct dac_module *const dev_inst, enum dac_channel channel, const uint16_t data)
	Write to the DAC. More...

enum status_code	dac_chan_write_buffer_wait (struct dac_module const module_inst, enum dac_channel channel, uint16_t buffer, uint32_t length)
	Write to the DAC. More...

Status Management
uint32_t	dac_get_status (struct dac_module *const module_inst)
	Retrieves the current module status. More...

void	dac_clear_status (struct dac_module *const module_inst, uint32_t status_flags)
	Clears a module status flag. More...

Callback Configuration and Initialization
enum status_code	dac_chan_write_buffer_job (struct dac_module const module_inst, const enum dac_channel channel, uint16_t buffer, uint32_t buffer_size)
	Convert a specific number digital data to analog through DAC. More...

enum status_code	dac_chan_write_job (struct dac_module *const module_inst, const enum dac_channel channel, uint16_t data)
	Convert one digital data job. More...

enum status_code	dac_register_callback (struct dac_module *const module, const enum dac_channel channel, const dac_callback_t callback, const enum dac_callback type)
	Registers an asynchronous callback function with the driver. More...

enum status_code	dac_unregister_callback (struct dac_module *const module, const enum dac_channel channel, const enum dac_callback type)
	Unregisters an asynchronous callback function with the driver. More...

Callback Enabling and Disabling (Channel)
enum status_code	dac_chan_enable_callback (struct dac_module *const module, const enum dac_channel channel, const enum dac_callback type)
	Enables asynchronous callback generation for a given channel and type. More...

enum status_code	dac_chan_disable_callback (struct dac_module *const module, const enum dac_channel channel, const enum dac_callback type)
	Disables asynchronous callback generation for a given channel and type. More...

enum status_code	dac_chan_get_job_status (struct dac_module *module_inst, const enum dac_channel channel)
	Gets the status of a job. More...

void	dac_chan_abort_job (struct dac_module *module_inst, const enum dac_channel channel)
	Aborts an ongoing job. More...

DAC Status Flags
DAC status flags, returned by dac_get_status() and cleared by dac_clear_status().
#define	DAC_STATUS_CHANNEL_0_EMPTY (1UL << 0)
	Data Buffer Empty Channel 0 - Set when data is transferred from DATABUF to DATA by a start conversion event and DATABUF is ready for new data. More...

#define	DAC_STATUS_CHANNEL_1_EMPTY (1UL << 1)
	Data Buffer Empty Channel 1 - Set when data is transferred from DATABUF to DATA by a start conversion event and DATABUF is ready for new data. More...

#define	DAC_STATUS_CHANNEL_0_UNDERRUN (1UL << 2)
	Underrun Channel 0 - Set when a start conversion event occurs when DATABUF is empty. More...

#define	DAC_STATUS_CHANNEL_1_UNDERRUN (1UL << 3)
	Underrun Channel 1 - Set when a start conversion event occurs when DATABUF is empty. More...

Status Management (Channel)
bool	dac_chan_is_end_of_conversion (struct dac_module *const module_inst, enum dac_channel channel)
	Retrieves the status of DAC channel end of conversion. More...

#define DAC_STATUS_CHANNEL_0_EMPTY (1UL << 0)

Data Buffer Empty Channel 0 - Set when data is transferred from DATABUF to DATA by a start conversion event and DATABUF is ready for new data.

Referenced by dac_clear_status(), and dac_get_status().

#define DAC_STATUS_CHANNEL_0_UNDERRUN (1UL << 2)

Underrun Channel 0 - Set when a start conversion event occurs when DATABUF is empty.

Referenced by dac_clear_status(), and dac_get_status().

#define DAC_STATUS_CHANNEL_1_EMPTY (1UL << 1)

Data Buffer Empty Channel 1 - Set when data is transferred from DATABUF to DATA by a start conversion event and DATABUF is ready for new data.

Referenced by dac_clear_status(), and dac_get_status().

#define DAC_STATUS_CHANNEL_1_UNDERRUN (1UL << 3)

Underrun Channel 1 - Set when a start conversion event occurs when DATABUF is empty.

Referenced by dac_clear_status(), and dac_get_status().

#define DAC_TIMEOUT 0xFFFF

Define DAC features set according to different device families.

Referenced by dac_chan_write_buffer_wait().

typedef void(* dac_callback_t)(uint8_t channel)

Type definition for a DAC module callback function.

enum dac_callback

Enum for the possible callback types for the DAC module.

Enumerator
DAC_CALLBACK_DATA_EMPTY	Callback type for when a DAC channel data empty condition occurs (requires event triggered mode)
DAC_CALLBACK_DATA_UNDERRUN	Callback type for when a DAC channel data underrun condition occurs (requires event triggered mode)
DAC_CALLBACK_TRANSFER_COMPLETE	Callback type for when a DAC channel write buffer job complete (requires event triggered mode)

enum dac_channel

DAC channel selection enum.

Enum for the DAC channel selection.

Enumerator
DAC_CHANNEL_0	DAC output channel 0.
DAC_CHANNEL_1	DAC output channel 1.

enum dac_current_ctrl

DAC current control enum.

Enum for the current in output buffer according the conversion rate.

Enumerator
DAC_CURRENT_100K	GCLK_DAC <= 1.2MHz.
DAC_CURRENT_1M	1.2MHz < GCLK_DAC <= 6MHz
DAC_CURRENT_12M	6MHz < GCLK_DAC <= 12MHz
DAC_CURRENT_RESERVED	Reserved.

enum dac_reference

DAC reference voltage enum.

Enum for the possible reference voltages for the DAC.

Enumerator
DAC_REFERENCE_VREFPU	Unbuffered external voltage reference.
DAC_REFERENCE_VDDANA	Analog VCC as reference.
DAC_REFERENCE_VREFPB	Buffered external voltage reference.
DAC_REFERENCE_INTREF	Internal bandgap reference.

void dac_chan_abort_job	(	struct dac_module *	module_inst,
		const enum dac_channel	channel
	)

Aborts an ongoing job.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Logical channel to enable callback function

References Assert, DAC_CHANNEL_0, DAC_CHANNEL_1, and STATUS_ABORTED.

void dac_chan_disable	(	struct dac_module *const	module_inst,
		enum dac_channel	channel
	)

Disable a DAC channel.

Disables the selected DAC channel.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Channel to disable

References Assert.

enum status_code dac_chan_disable_callback	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		const enum dac_callback	type
	)

Disables asynchronous callback generation for a given channel and type.

Disables asynchronous callbacks for a given logical DAC channel and type.

Parameters

[in,out]	dac_module	Pointer to the DAC software instance struct
[in]	channel	Logical channel to disable callback function
[in]	type	Type of callback function callbacks to disable

Returns: Status of the callback disable operation.

Return values

STATUS_OK	The callback was disabled successfully
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode

References Assert, STATUS_ERR_UNSUPPORTED_DEV, STATUS_OK, and UNUSED.

void dac_chan_enable	(	struct dac_module *const	module_inst,
		enum dac_channel	channel
	)

Enable a DAC channel.

Enables the selected DAC channel.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Channel to enable

References Assert.

Referenced by test_dac_init().

enum status_code dac_chan_enable_callback	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		const enum dac_callback	type
	)

Enables asynchronous callback generation for a given channel and type.

Enables asynchronous callbacks for a given logical DAC channel and type. This must be called before a DAC channel will generate callback events.

Parameters

[in,out]	dac_module	Pointer to the DAC software instance struct
[in]	channel	Logical channel to enable callback function
[in]	type	Type of callback function callbacks to enable

Returns: Status of the callback enable operation.

Return values

STATUS_OK	The callback was enabled successfully
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode

References Assert, STATUS_ERR_UNSUPPORTED_DEV, and STATUS_OK.

void dac_chan_get_config_defaults ( struct dac_chan_config *const config )

References Assert, dac_chan_config::current, DAC_CURRENT_12M, dac_chan_config::dither_mode, dac_chan_config::left_adjust, dac_chan_config::refresh_period, and dac_chan_config::run_in_standby.

Referenced by test_dac_init().

enum status_code dac_chan_get_job_status	(	struct dac_module *	module_inst,
		const enum dac_channel	channel
	)

Gets the status of a job.

Gets the status of an ongoing or the last job.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Logical channel to enable callback function

Returns: Status of the job.

References Assert.

bool dac_chan_is_end_of_conversion	(	struct dac_module *const	module_inst,
		enum dac_channel	channel
	)

Retrieves the status of DAC channel end of conversion.

Checks if the conversion is completed or not and returns boolean flag of status.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Channel to disable

Return values

true	Conversion is complete, VOUT is stable
false	No conversion completed since last load of DATA

References Assert.

void dac_chan_set_config	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		struct dac_chan_config *const	config
	)

Writes a DAC channel configuration to the hardware module.

Writes out a given channel configuration to the hardware module.

Note: The DAC device instance structure must be initialized before calling this function.

Parameters

[in]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Channel to configure
[in]	config	Pointer to the configuration struct

References Assert, dac_chan_config::current, DAC_CHANNEL_0, DAC_CHANNEL_1, system_pinmux_config::direction, dac_chan_config::dither_mode, system_pinmux_config::input_pull, dac_chan_config::left_adjust, system_pinmux_config::mux_position, dac_chan_config::refresh_period, dac_chan_config::run_in_standby, system_pinmux_get_config_defaults(), SYSTEM_PINMUX_PIN_DIR_INPUT, SYSTEM_PINMUX_PIN_PULL_NONE, and system_pinmux_pin_set_config().

Referenced by test_dac_init().

enum status_code dac_chan_write	(	struct dac_module *const	module_inst,
		enum dac_channel	channel,
		const uint16_t	data
	)

Write to the DAC.

This function writes to the DATA or DATABUF register. If the conversion is not event-triggered, the data will be written to the DATA register and the conversion will start. If the conversion is event-triggered, the data will be written to DATABUF and transferred to the DATA register and converted when a Start Conversion Event is issued. Conversion data must be right or left adjusted according to configuration settings.

Note: To be event triggered, the enable_start_on_event must be enabled in the configuration.

Parameters

[in]	module_inst	Pointer to the DAC software device struct
[in]	channel	DAC channel to write to
[in]	data	Conversion data

Returns: Status of the operation.

Return values

STATUS_OK If the data was written

References Assert, dac_is_syncing(), and STATUS_OK.

Referenced by dac_chan_write_buffer_wait(), run_adc_average_mode_test(), run_adc_callback_mode_test(), run_adc_polled_mode_test(), run_adc_window_mode_test(), and setup_adc_window_mode_test().

enum status_code dac_chan_write_buffer_job	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		uint16_t *	buffer,
		uint32_t	length
	)

Convert a specific number digital data to analog through DAC.

This function will perform a conversion of specific number of digital data. The conversion should be event-triggered, the data will be written to DATABUF and transferred to the DATA register and converted when a Start Conversion Event is issued. Conversion data must be right or left adjusted according to configuration settings.

Note: To be event triggered, the enable_start_on_event must be enabled in the configuration.

Parameters

[in]	module_inst	Pointer to the DAC software device struct
[in]	channel	DAC channel to write to
[in]	buffer	Pointer to the digital data write buffer to be converted
[in]	length	Size of the write buffer

Returns: Status of the operation.

Return values

STATUS_OK	If the data was written
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode
STATUS_BUSY	The DAC is busy and can not accept a new job

References Assert, DAC_CHANNEL_0, DAC_CHANNEL_1, dac_is_syncing(), STATUS_BUSY, STATUS_ERR_UNSUPPORTED_DEV, STATUS_OK, system_interrupt_enable(), and SYSTEM_INTERRUPT_MODULE_DAC.

Referenced by dac_chan_write_job().

enum status_code dac_chan_write_buffer_wait	(	struct dac_module *const	module_inst,
		enum dac_channel	channel,
		uint16_t *	buffer,
		uint32_t	length
	)

Write to the DAC.

This function converts a specific number of digital data. The conversion should be event-triggered, the data will be written to DATABUF and transferred to the DATA register and converted when a Start Conversion Event is issued. Conversion data must be right or left adjusted according to configuration settings.

Note: To be event triggered, the enable_start_on_event must be enabled in the configuration.

Parameters

[in]	module_inst	Pointer to the DAC software device struct
[in]	channel	DAC channel to write to
[in]	buffer	Pointer to the digital data write buffer to be converted
[in]	length	Length of the write buffer

Returns: Status of the operation.

Return values

STATUS_OK	If the data was written or no data conversion required
STATUS_ERR_UNSUPPORTED_DEV	The DAC is not configured as using event trigger
STATUS_BUSY	The DAC is busy and can not do the conversion

References Assert, dac_chan_write(), DAC_CHANNEL_0, DAC_CHANNEL_1, dac_is_syncing(), DAC_TIMEOUT, STATUS_BUSY, STATUS_ERR_TIMEOUT, STATUS_ERR_UNSUPPORTED_DEV, and STATUS_OK.

enum status_code dac_chan_write_job	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		uint16_t	data
	)

Convert one digital data job.

This function will perform a conversion of specfic number of digital data. The conversion is event-triggered, the data will be written to DATABUF and transferred to the DATA register and converted when a Start Conversion Event is issued. Conversion data must be right or left adjusted according to configuration settings.

Note: To be event triggered, the enable_start_on_event must be enabled in the configuration.

Parameters

[in]	module_inst	Pointer to the DAC software device struct
[in]	channel	DAC channel to write to
[in]	data	Digital data to be converted

Returns: Status of the operation.

Return values

STATUS_OK	If the data was written
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode
STATUS_BUSY	The DAC is busy and can not accept a new job

References Assert, dac_chan_write_buffer_job(), STATUS_BUSY, STATUS_ERR_UNSUPPORTED_DEV, and STATUS_OK.

void dac_clear_status	(	struct dac_module *const	module_inst,
		uint32_t	status_flags
	)

Clears a module status flag.

Clears the given status flag of the module.

Parameters

[in]	module_inst	Pointer to the DAC software device struct
[in]	status_flags	Bit mask of status flags to clear

References Assert, DAC_STATUS_CHANNEL_0_EMPTY, DAC_STATUS_CHANNEL_0_UNDERRUN, DAC_STATUS_CHANNEL_1_EMPTY, and DAC_STATUS_CHANNEL_1_UNDERRUN.

void dac_disable ( struct dac_module *const module_inst )

Disable the DAC module.

Disables the DAC interface and the output buffer.

Parameters

[in] module_inst Pointer to the DAC software instance struct

References Assert, and dac_is_syncing().

void dac_disable_events	(	struct dac_module *const	module_inst,
		struct dac_events *const	events
	)

Disables a DAC event input or output.

Disables one or more input or output events to or from the DAC module. See Struct dac_events for a list of events this module supports.

Note: Events cannot be altered while the module is enabled.

Parameters

[in]	module_inst	Software instance for the DAC peripheral
[in]	events	Struct containing flags of events to disable

References Assert, DAC_CHANNEL_0, DAC_CHANNEL_1, dac_events::generate_event_on_chan0_buffer_empty, dac_events::on_event_chan0_start_conversion, and dac_events::on_event_chan1_start_conversion.

void dac_enable ( struct dac_module *const module_inst )

Enable the DAC module.

Enables the DAC interface and the selected output. If any internal reference is selected it will be enabled.

Parameters

[in] module_inst Pointer to the DAC software instance struct

References Assert, DAC_CHANNEL_0, DAC_CHANNEL_1, dac_is_syncing(), DAC_REFERENCE_INTREF, system_voltage_reference_enable(), and SYSTEM_VOLTAGE_REFERENCE_OUTPUT.

Referenced by test_dac_init().

void dac_enable_events	(	struct dac_module *const	module_inst,
		struct dac_events *const	events
	)

Enables a DAC event input or output.

Enables one or more input or output events to or from the DAC module. See Struct dac_events for a list of events this module supports.

Note: Events cannot be altered while the module is enabled.

Parameters

[in]	module_inst	Software instance for the DAC peripheral
[in]	events	Struct containing flags of events to enable

References Assert, DAC_CHANNEL_0, DAC_CHANNEL_1, dac_events::generate_event_on_chan0_buffer_empty, dac_events::generate_event_on_chan0_falling_edge, dac_events::generate_event_on_chan1_buffer_empty, dac_events::generate_event_on_chan1_falling_edge, dac_events::on_event_chan0_start_conversion, and dac_events::on_event_chan1_start_conversion.

void dac_get_config_defaults ( struct dac_config *const config )

Initializes a DAC configuration structure to defaults.

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

The default configuration is as follows:

1V from internal bandgap reference
Drive the DAC output to the VOUT pin
Right adjust data
GCLK generator 0 (GCLK main) clock source
The output buffer is disabled when the chip enters STANDBY sleep mode

Parameters

[out] config Configuration structure to initialize to default values

References Assert, dac_config::clock_source, DAC_REFERENCE_INTREF, dac_config::differential_mode, GCLK_GENERATOR_0, and dac_config::reference.

Referenced by test_dac_init().

uint32_t dac_get_status ( struct dac_module *const module_inst )

Retrieves the current module status.

Checks the status of the module and returns it as a bitmask of status flags.

Parameters

[in] module_inst Pointer to the DAC software device struct

Returns: Bitmask of status flags.

Return values

DAC_STATUS_CHANNEL_0_EMPTY	Data has been transferred from DATABUF to DATA by a start conversion event and DATABUF is ready for new data
DAC_STATUS_CHANNEL_0_UNDERRUN	A start conversion event has occurred when DATABUF is empty

References Assert, DAC_STATUS_CHANNEL_0_EMPTY, DAC_STATUS_CHANNEL_0_UNDERRUN, DAC_STATUS_CHANNEL_1_EMPTY, and DAC_STATUS_CHANNEL_1_UNDERRUN.

enum status_code dac_init	(	struct dac_module *const	module_inst,
		Dac *const	module,
		struct dac_config *const	config
	)

Initialize the DAC device struct.

Use this function to initialize the Digital to Analog Converter. Resets the underlying hardware module and configures it.

Note: The DAC channel must be configured separately.

Parameters

[out]	module_inst	Pointer to the DAC software instance struct
[in]	module	Pointer to the DAC module instance
[in]	config	Pointer to the config struct, created by the user application

Returns: Status of initialization.

Return values

STATUS_OK	Module initiated correctly
STATUS_ERR_DENIED	If module is enabled
STATUS_BUSY	If module is busy resetting

References _dac_instances, _dac_set_config(), Assert, dac_config::clock_source, dac_config::reference, system_gclk_chan_config::source_generator, STATUS_BUSY, STATUS_ERR_DENIED, STATUS_OK, system_apb_clock_set_mask(), SYSTEM_CLOCK_APB_APBC, system_gclk_chan_enable(), system_gclk_chan_get_config_defaults(), and system_gclk_chan_set_config().

Referenced by test_dac_init().

bool dac_is_syncing ( struct dac_module *const dev_inst )

Determines if the hardware module(s) are currently synchronizing to the bus.

Checks to see if the underlying hardware peripheral module(s) are currently synchronizing across multiple clock domains to the hardware bus. This function can be used to delay further operations on a module until such time that it is ready, to prevent blocking delays for synchronization in the user application.

Parameters

[in] dev_inst Pointer to the DAC software instance struct

Returns: Synchronization status of the underlying hardware module(s).

Return values

true	If the module synchronization is ongoing
false	If the module has completed synchronization

References Assert.

Referenced by dac_chan_write(), dac_chan_write_buffer_job(), dac_chan_write_buffer_wait(), dac_disable(), dac_enable(), and dac_reset().

enum status_code dac_register_callback	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		const dac_callback_t	callback,
		const enum dac_callback	type
	)

Registers an asynchronous callback function with the driver.

Registers an asynchronous callback with the DAC driver, fired when a callback condition occurs.

Parameters

[in,out]	module_inst	Pointer to the DAC software instance struct
[in]	callback	Pointer to the callback function to register
[in]	channel	Logical channel to register callback function
[in]	type	Type of callback function to register

Returns: Status of the registration operation.

Return values

STATUS_OK	The callback was registered successfully
STATUS_ERR_INVALID_ARG	If an invalid callback type was supplied
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode

References Assert, STATUS_ERR_INVALID_ARG, STATUS_ERR_UNSUPPORTED_DEV, and STATUS_OK.

void dac_reset ( struct dac_module *const module_inst )

Resets the DAC module.

This function will reset the DAC module to its power on default values and disable it.

Parameters

[in] module_inst Pointer to the DAC software instance struct

References Assert, and dac_is_syncing().

enum status_code dac_unregister_callback	(	struct dac_module *const	module_inst,
		const enum dac_channel	channel,
		const enum dac_callback	type
	)

Unregisters an asynchronous callback function with the driver.

Unregisters an asynchronous callback with the DAC driver, removing it from the internal callback registration table.

Parameters

[in,out]	module_inst	Pointer to the DAC software instance struct
[in]	channel	Logical channel to unregister callback function
[in]	type	Type of callback function to unregister

Returns: Status of the de-registration operation.

Return values

STATUS_OK	The callback was unregistered successfully
STATUS_ERR_INVALID_ARG	If an invalid callback type was supplied
STATUS_ERR_UNSUPPORTED_DEV	If a callback that requires event driven mode was specified with a DAC instance configured in non-event mode

References Assert, STATUS_ERR_INVALID_ARG, STATUS_ERR_UNSUPPORTED_DEV, and STATUS_OK.

Microchip® Advanced Software Framework

Prerequisites

Module Overview

Conversion Range

Conversion

Analog Output

Events

Left and Right Adjusted Values

Clock Sources

Special Considerations

Sleep Mode

Conversion Time

Extra Information

Examples

API Overview

Data Structures

Macros

Typedefs

Enumerations

Configuration and Initialization

Configuration and Initialization (Channel)

Channel Data Management

Status Management

Callback Configuration and Initialization

Callback Enabling and Disabling (Channel)

DAC Status Flags

Status Management (Channel)