Detailed Description

Digital to Analog Conversion (DAC) Output Driver.

Overview

The DAC driver allows you to manage a Digital to Analog peripheral via simple and portable APIs. This driver supports converting DAC codes into an analog voltage with varying degrees of precision (microvolts or millivolts) depending on the resolution of the DAC.

Usage

This documentation provides a basic usage summary and a set of examples in the form of commented code fragments. Detailed descriptions of the APIs are provided in subsequent sections.

Synopsis

// Import DAC Driver definitions
#include <ti/drivers/DAC.h>
// Define name for DAC channel index
#define VREFERENCE_OUT  0
// One-time init of DAC driver
DAC_init();
// Initialize optional DAC parameters
DAC_Params params;
DAC_Params_init(&params);
// Open DAC channels for usage
DAC_Handle dacHandle = DAC_open(VREFERENCE_OUT, &params);
// Enable the DAC channel
DAC_enable(dacHandle);
// Output 800mV using the DAC
DAC_setVoltage(dacHandle, 800000);
// Output a voltage using DAC codes
DAC_setCode(dacHandle, 125);
// Disable the DAC channel
DAC_disable(dacHandle);
// Close the DAC channel
DAC_close(dacHandle);

Examples

Opening a DAC instance

DAC_Handle dac;
DAC_Params params;
DAC_Params_init(&params);
dac = DAC_open(0, &params);
if (dac == NULL) {
    // DAC_open() failed
    while (1) {}
}

Using DAC to set a reference voltage

To set a reference voltage first enable the DAC with DAC_enable() and then set the desired output voltage with DAC_setVoltage(). The returned value can be used to check if the call was successful.

int_fast16_t res;
uint32_t outputMicroVolts = 1500000;
DAC_enable(dac);
res = DAC_setVoltage(dac, outputMicroVolts);
if (res == DAC_STATUS_SUCCESS)
{
    printf(outputMicroVolts);
}

Using DAC to set a code

The following example shows how to set a DAC code. The use of DAC_setCode() instead of DAC_setVoltage() comes handy in scenarios such as outputting a data buffer at a particular time rate (e.g. waveform generation). Nevertheless, it's important to remember that DAC codes produce different output voltages depending on the selected voltage reference source.

int_fast16_t res;
uint32_t outputCode = 127;
DAC_enable(dac);
res = DAC_setCode(dac, outputCode);
if (res == DAC_STATUS_SUCCESS)
{
    printf(outputCode);
}

Configuration

Refer to the Driver's Configuration section for driver configuration information.

#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include <ti/devices/DeviceFamily.h>
#include <DeviceFamily_constructPath(driverlib/aux_dac.h)>

Include dependency graph for DAC.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	DAC_Config
	DAC Global configuration. More...

struct	DAC_Params
	Basic DAC Parameters. More...

Macros
#define	DAC_STATUS_SUCCESS (0)
	Successful status code returned by DAC API. More...

#define	DAC_STATUS_ERROR (-1)
	Generic error status code returned by DAC API. More...

#define	DAC_STATUS_INUSE (-2)
	The DAC is currently in use by another handle or by the sensor controller. More...

#define	DAC_STATUS_INVALID (-3)
	The desired output value is outside the DAC's output range. More...

Typedefs
typedef DAC_Config *	DAC_Handle
	A handle that is returned from a DAC_open() call. More...

Functions
void	DAC_init (void)
	Function to initialize the DAC module. More...

DAC_Handle	DAC_open (uint_least8_t index, DAC_Params *params)
	Function to initialize a given DAC peripheral specified by the particular index value. More...

void	DAC_close (DAC_Handle handle)
	Function to close a given DAC peripheral specified by the DAC handle. More...

int_fast16_t	DAC_setVoltage (DAC_Handle handle, uint32_t uVoltOutput)
	Function to set the DAC voltage value in microvolts. More...

int_fast16_t	DAC_setCode (DAC_Handle handle, uint32_t code)
	Function to set the DAC voltage in terms of a DAC code. More...

int_fast16_t	DAC_enable (DAC_Handle handle)
	Function to enable the DAC's output. More...

int_fast16_t	DAC_disable (DAC_Handle handle)
	Function to disable the DAC's output. More...

void	DAC_Params_init (DAC_Params *params)
	Function to initialize the DAC_Params struct to its defaults. More...

Variables
const DAC_Params	DAC_defaultParams
	Default DAC_Params structure. More...

Macro Definition Documentation

§ DAC_STATUS_SUCCESS

#define DAC_STATUS_SUCCESS (0)

Successful status code returned by DAC API.

§ DAC_STATUS_ERROR

#define DAC_STATUS_ERROR (-1)

Generic error status code returned by DAC API.

§ DAC_STATUS_INUSE

#define DAC_STATUS_INUSE (-2)

The DAC is currently in use by another handle or by the sensor controller.

§ DAC_STATUS_INVALID

#define DAC_STATUS_INVALID (-3)

The desired output value is outside the DAC's output range.

Typedef Documentation

§ DAC_Handle

typedef DAC_Config* DAC_Handle

A handle that is returned from a DAC_open() call.

Function Documentation

§ DAC_init()

void DAC_init ( void )

Function to initialize the DAC module.

Precondition: The DAC_config structure must exist and be persistent before this function can be called. This function must also be called before any other DAC driver APIs. This function call does not modify any peripheral registers.

§ DAC_open()

DAC_Handle DAC_open	(	uint_least8_t	index,
		DAC_Params *	params
	)

Function to initialize a given DAC peripheral specified by the particular index value.

Precondition: DAC controller has been initialized

Parameters

[in,out]	index	Logical peripheral number for the DAC indexed into the DAC_config table
[in]	params	Pointer to a parameter block. All the fields in this structure are RO (read-only). Providing a NULL pointer cannot open the module.

Returns: A DAC_Handle on success or a NULL on an error or if it has been opened already.

See also: DAC_init(); DAC_close()

§ DAC_close()

void DAC_close ( DAC_Handle handle )

Function to close a given DAC peripheral specified by the DAC handle.

Precondition: DAC_open() had to be called first.

Parameters

[in] handle A DAC_Handle returned from DAC_open

See also: DAC_open()

§ DAC_setVoltage()

int_fast16_t DAC_setVoltage	(	DAC_Handle	handle,
		uint32_t	uVoltOutput
	)

Function to set the DAC voltage value in microvolts.

Warning: This function takes a value in microvolts, but the actual output is limited by the DAC's resolution.

Precondition: DAC_enable() has to be called first.

Parameters

[in]	handle	A DAC_Handle returned from DAC_open.
[in]	uVoltOutput	Desired output voltage in uV.

Returns: Implementation specific return codes. Negative values indicate unsuccessful operations.

Return values

DAC_STATUS_SUCCESS	The call was successful.
DAC_STATUS_ERROR	The call was unsuccessful.
DAC_STATUS_INVALID	The desired output voltage was out of bounds for the DAC.

See also: DAC_setCode()

§ DAC_setCode()

int_fast16_t DAC_setCode	(	DAC_Handle	handle,
		uint32_t	code
	)

Function to set the DAC voltage in terms of a DAC code.

Warning: The appropriate DAC code is device-specific and admissible values depend on the DAC's resolution.

Precondition: DAC_open() has to be called first.

Parameters

[in]	handle	A DAC_Handle returned from DAC_open.
[in]	code	Desired output in terms of a DAC code.

Return values

DAC_STATUS_SUCCESS	The call was successful.
DAC_STATUS_ERROR	The call was unsuccessful.

See also: DAC_open()

§ DAC_enable()

int_fast16_t DAC_enable ( DAC_Handle handle )

Function to enable the DAC's output.

This function claims ownership of the DAC peripheral, and depending on the selected voltage reference source, it calculates the output voltage range.

Furthermore, the function configures and enables the DAC.

Precondition: DAC_open() has to be called first.

Parameters

[in] handle A DAC_Handle returned from DAC_open.

Return values

DAC_STATUS_SUCCESS	The call was successful.
DAC_STATUS_ERROR	The call was unsuccessful.
DAC_STATUS_INUSE	The call was unsuccessful because the DAC is in use by the Sensor Controller or by another handle.

See also: DAC_disable()

§ DAC_disable()

int_fast16_t DAC_disable ( DAC_Handle handle )

Function to disable the DAC's output.

Precondition: DAC_enable() has to be called first.

Parameters

[in] handle A DAC_Handle returned from DAC_open.

Return values

DAC_STATUS_SUCCESS	The call was successful.
DAC_STATUS_ERROR	The call was unsuccessful.

See also: DAC_enable()

§ DAC_Params_init()

void DAC_Params_init ( DAC_Params * params )

Function to initialize the DAC_Params struct to its defaults.

Parameters

[out] params A pointer to DAC_Params structure for initialization

Defaults values are:

params.initCode = 0,

params.custom = NULL;

Parameters

params Parameter structure to initialize

Variable Documentation

§ DAC_defaultParams

const DAC_Params DAC_defaultParams

Default DAC_Params structure.

See also: DAC_Params_init()

Detailed Description

Overview

Usage

Synopsis

Examples

Opening a DAC instance

Using DAC to set a reference voltage

Using DAC to set a code

Configuration

Data Structures

Macros

Typedefs

Functions

Variables

Macro Definition Documentation

§ DAC_STATUS_SUCCESS

§ DAC_STATUS_ERROR

§ DAC_STATUS_INUSE

§ DAC_STATUS_INVALID

Typedef Documentation

§ DAC_Handle

Function Documentation

§ DAC_init()

§ DAC_open()

§ DAC_close()

§ DAC_setVoltage()

§ DAC_setCode()

§ DAC_enable()

§ DAC_disable()

§ DAC_Params_init()

Variable Documentation

§ DAC_defaultParams