DAC

DAC peripheral driver interface. More...

Detailed Description

DAC peripheral driver interface.

Similar to the ADC driver interface (ADC), the DAC interface uses the concept of lines, corresponds to a tuple of a DAC device and a DAC output channel.

The DAC interface expects data to be served as a 16-bit unsigned integer, independent of the actual resolution of the hardware device. It is up to the DAC driver, to scale the given value to the maximal width that can be handled. The device driver should, on the other hand, implement the DAC in a way, that it will use the bit width, that comes closest to 16-bit.

This kind of 'auto-scaling' is quite sufficient for this interface, as standard DAC peripherals use a fixed conversion resolution internally anyway, so that any particular bit-width configuration on this driver level would not have much effect...

(Low-) Power Implications

The configured DAC peripherals are active (and consume power) from the point of initialization. When calling dac_poweroff(), the implementation should disable the given DAC line and put the DAC peripheral to sleep (e.g. through peripheral clock gating). When woken up again through dac_poweron(), the given DAC line should transparently continue it's previous operation.

The DAC driver implementation may need to block (and free) certain power modes in the driver's dac_init(), dac_poweron(), and the dac_poweroff() functions.

Files
file	dac.h
	DAC peripheral driver interface definition.

Macros
#define	DAC_UNDEF   (UINT_MAX)
	Default DAC undefined value.
#define	DAC_LINE(x)   (x)
	Default DAC access macro.

Typedefs
typedef unsigned int	dac_t
	Define default DAC type identifier.

Enumerations
enum	{ DAC_OK = 0, DAC_NOLINE = -1 }
	Return codes used by the DAC driver interface.

Functions
int8_t	dac_init (dac_t line)
	Initialize the given DAC line. More...
void	dac_set (dac_t line, uint16_t value)
	Write a value onto DAC Device on a given Channel. More...
void	dac_poweron (dac_t line)
	Enable the given DAC line. More...
void	dac_poweroff (dac_t line)
	Disable the given DAC line. More...

Function Documentation

dac_init()

int8_t dac_init

(

dac_t

line

)

Initialize the given DAC line.

After initialization, the corresponding DAC line is active and its output is set to 0.

Parameters

[in]

line

DAC line to initialize

Returns

DAC_OK on success

DAC_NOLINE on invalid DAC line

dac_poweroff()

void dac_poweroff

(

dac_t

line

)

Disable the given DAC line.

Parameters

[in]

line

DAC line to power off

dac_poweron()

void dac_poweron

(

dac_t

line

)

Enable the given DAC line.

Parameters

[in]

line

DAC line to power on

dac_set()

void dac_set	(	dac_t	line,
		uint16_t	value
	)

Write a value onto DAC Device on a given Channel.

The value is always given as 16-bit value and is internally scaled to the actual resolution that the DAC unit provides (e.g. 12-bit). So to get the maximum output voltage, this function has to be called with value set to 65535 (UINT16_MAX).

Parameters

[in]	line	DAC line to set
[in]	value	value to set line to