VDAC - Voltage DAC#

Digital to Analog Voltage Converter (VDAC) Peripheral API.

This module contains functions to control the VDAC peripheral of Silicon Labs' 32-bit MCUs and SoCs. VDAC converts digital values to analog signals at up to 500 ksps with 12-bit accuracy. VDAC is designed for low energy consumption, but can also provide very good performance.

The following steps are necessary for basic operation:

Clock enable:

CMU_ClockEnable(cmuClock_VDAC0, true);

Initialize the VDAC with default settings and modify selected fields:

VDAC_Init_TypeDef vdacInit          = VDAC_INIT_DEFAULT;
VDAC_InitChannel_TypeDef vdacChInit = VDAC_INITCHANNEL_DEFAULT;

// Set prescaler to get 1 MHz VDAC clock frequency.
vdacInit.prescaler = VDAC_PrescaleCalc(1000000, true, 0); // function call for series 0/1
VDAC_Init(VDAC0, &vdacInit);

vdacChInit.enable = true;
VDAC_InitChannel(VDAC0, &vdacChInit, 0);

Perform a conversion:

VDAC_ChannelOutputSet(VDAC0, 0, 250);

Note

The output stage of a VDAC channel consists of an on-chip operational amplifier (OPAMP) in the OPAMP module. This OPAMP is highly configurable; and to exploit the VDAC functionality fully, configure the OPAMP using the OPAMP API. Using the OPAMP API also loads OPAMP calibration values. The default (reset) settings of OPAMP is sufficient for many applications.

Modules#

VDAC_Init_TypeDef

VDAC_InitChannel_TypeDef

Enumerations#

enum

VDAC_Refresh_TypeDef {

vdacRefresh8 = _VDAC_CTRL_REFRESHPERIOD_8CYCLES

vdacRefresh16 = _VDAC_CTRL_REFRESHPERIOD_16CYCLES

vdacRefresh32 = _VDAC_CTRL_REFRESHPERIOD_32CYCLES

vdacRefresh64 = _VDAC_CTRL_REFRESHPERIOD_64CYCLES

}

Channel refresh period.

enum

VDAC_Ref_TypeDef {

vdacRef1V25Ln = _VDAC_CTRL_REFSEL_1V25LN

vdacRef2V5Ln = _VDAC_CTRL_REFSEL_2V5LN

vdacRef1V25 = _VDAC_CTRL_REFSEL_1V25

vdacRef2V5 = _VDAC_CTRL_REFSEL_2V5

vdacRefAvdd = _VDAC_CTRL_REFSEL_VDD

vdacRefExtPin = _VDAC_CTRL_REFSEL_EXT

}

Reference voltage for VDAC.

enum

VDAC_PrsSel_TypeDef {

vdacPrsSelCh0 = _VDAC_CH0CTRL_PRSSEL_PRSCH0

vdacPrsSelCh1 = _VDAC_CH0CTRL_PRSSEL_PRSCH1

vdacPrsSelCh2 = _VDAC_CH0CTRL_PRSSEL_PRSCH2

vdacPrsSelCh3 = _VDAC_CH0CTRL_PRSSEL_PRSCH3

vdacPrsSelCh4 = _VDAC_CH0CTRL_PRSSEL_PRSCH4

vdacPrsSelCh5 = _VDAC_CH0CTRL_PRSSEL_PRSCH5

vdacPrsSelCh6 = _VDAC_CH0CTRL_PRSSEL_PRSCH6

vdacPrsSelCh7 = _VDAC_CH0CTRL_PRSSEL_PRSCH7

vdacPrsSelCh8 = _VDAC_CH0CTRL_PRSSEL_PRSCH8

vdacPrsSelCh9 = _VDAC_CH0CTRL_PRSSEL_PRSCH9

vdacPrsSelCh10 = _VDAC_CH0CTRL_PRSSEL_PRSCH10

vdacPrsSelCh11 = _VDAC_CH0CTRL_PRSSEL_PRSCH11

}

Peripheral Reflex System signal used to trigger VDAC channel conversion.

enum

VDAC_TrigMode_TypeDef {

vdacTrigModeSw = _VDAC_CH0CTRL_TRIGMODE_SW

vdacTrigModePrs = _VDAC_CH0CTRL_TRIGMODE_PRS

vdacTrigModeRefresh = _VDAC_CH0CTRL_TRIGMODE_REFRESH

vdacTrigModeSwPrs = _VDAC_CH0CTRL_TRIGMODE_SWPRS

vdacTrigModeSwRefresh = _VDAC_CH0CTRL_TRIGMODE_SWREFRESH

vdacTrigModeLesense = _VDAC_CH0CTRL_TRIGMODE_LESENSE

}

Channel conversion trigger mode.

Functions#

void

VDAC_ChannelOutputSet(VDAC_TypeDef *vdac, unsigned int channel, uint32_t value)

Set the output signal of a VDAC channel to a given value.

void

VDAC_Enable(VDAC_TypeDef *vdac, unsigned int ch, bool enable)

Enable/disable the VDAC channel.

void

VDAC_Init(VDAC_TypeDef *vdac, const VDAC_Init_TypeDef *init)

Initialize VDAC.

void

VDAC_InitChannel(VDAC_TypeDef *vdac, const VDAC_InitChannel_TypeDef *init, unsigned int ch)

Initialize a VDAC channel.

void

VDAC_Channel0OutputSet(VDAC_TypeDef *vdac, uint32_t value)

Set the output signal of VDAC channel 0 to a given value.

void

VDAC_Channel1OutputSet(VDAC_TypeDef *vdac, uint32_t value)

Set the output signal of VDAC channel 1 to a given value.

void

VDAC_IntClear(VDAC_TypeDef *vdac, uint32_t flags)

Clear one or more pending VDAC interrupts.

void

VDAC_IntDisable(VDAC_TypeDef *vdac, uint32_t flags)

Disable one or more VDAC interrupts.

void

VDAC_IntEnable(VDAC_TypeDef *vdac, uint32_t flags)

Enable one or more VDAC interrupts.

uint32_t

VDAC_IntGet(VDAC_TypeDef *vdac)

Get pending VDAC interrupt flags.

uint32_t

VDAC_IntGetEnabled(VDAC_TypeDef *vdac)

Get enabled and pending VDAC interrupt flags.

void

VDAC_IntSet(VDAC_TypeDef *vdac, uint32_t flags)

Set one or more pending VDAC interrupts from SW.

uint32_t

VDAC_PrescaleCalc(uint32_t vdacFreq, bool syncMode, uint32_t hfperFreq)

Calculate the prescaler value used to determine VDAC clock.

void

VDAC_Reset(VDAC_TypeDef *vdac)

Reset VDAC to same state that it was in after a hardwares reset.

Macros#

#define

VDAC_INIT_DEFAULT undefined

Default configuration for VDAC initialization structure.

#define

VDAC_INITCHANNEL_DEFAULT undefined

Default configuration for VDAC channel initialization structure.

Enumeration Documentation#

VDAC_Refresh_TypeDef#

VDAC_Refresh_TypeDef

Channel refresh period.

Enumerator
vdacRefresh8	Refresh every 8 clock cycles.
vdacRefresh16	Refresh every 16 clock cycles.
vdacRefresh32	Refresh every 32 clock cycles.
vdacRefresh64	Refresh every 64 clock cycles.

VDAC_Ref_TypeDef#

VDAC_Ref_TypeDef

Reference voltage for VDAC.

Enumerator
vdacRef1V25Ln	Internal low noise 1.25 V band gap reference.
vdacRef2V5Ln	Internal low noise 2.5 V band gap reference.
vdacRef1V25	Internal 1.25 V band gap reference.
vdacRef2V5	Internal 2.5 V band gap reference.
vdacRefAvdd	AVDD reference.
vdacRefExtPin	External pin reference.

VDAC_PrsSel_TypeDef#

VDAC_PrsSel_TypeDef

Peripheral Reflex System signal used to trigger VDAC channel conversion.

Enumerator
vdacPrsSelCh0	PRS ch 0 triggers conversion.
vdacPrsSelCh1	PRS ch 1 triggers conversion.
vdacPrsSelCh2	PRS ch 2 triggers conversion.
vdacPrsSelCh3	PRS ch 3 triggers conversion.
vdacPrsSelCh4	PRS ch 4 triggers conversion.
vdacPrsSelCh5	PRS ch 5 triggers conversion.
vdacPrsSelCh6	PRS ch 6 triggers conversion.
vdacPrsSelCh7	PRS ch 7 triggers conversion.
vdacPrsSelCh8	PRS ch 8 triggers conversion.
vdacPrsSelCh9	PRS ch 9 triggers conversion.
vdacPrsSelCh10	PRS ch 10 triggers conversion.
vdacPrsSelCh11	PRS ch 11 triggers conversion.

VDAC_TrigMode_TypeDef#

VDAC_TrigMode_TypeDef

Channel conversion trigger mode.

Enumerator
vdacTrigModeSw	Channel is triggered by CHnDATA or COMBDATA write.
vdacTrigModePrs	Channel is triggered by PRS input.
vdacTrigModeRefresh	Channel is triggered by Refresh timer.
vdacTrigModeSwPrs	Channel is triggered by CHnDATA/COMBDATA write or PRS input.
vdacTrigModeSwRefresh	Channel is triggered by CHnDATA/COMBDATA write or Refresh timer.
vdacTrigModeLesense	Channel is triggered by LESENSE.

Function Documentation#

VDAC_ChannelOutputSet#

void VDAC_ChannelOutputSet (VDAC_TypeDef * vdac, unsigned int channel, uint32_t value)

Set the output signal of a VDAC channel to a given value.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	A pointer to the VDAC peripheral register block.
unsigned int	[in]	channel	A channel number to set the output of.
uint32_t	[in]	value	A value to write to the channel output register CHnDATA.

This function sets the output signal of a VDAC channel by writing value to the corresponding CHnDATA register.

VDAC_Enable#

void VDAC_Enable (VDAC_TypeDef * vdac, unsigned int ch, bool enable)

Enable/disable the VDAC channel.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	A pointer to the VDAC peripheral register block.
unsigned int	[in]	ch	A channel to enable/disable.
bool	[in]	enable	True to enable VDAC channel, false to disable.

VDAC_Init#

void VDAC_Init (VDAC_TypeDef * vdac, const VDAC_Init_TypeDef * init)

Initialize VDAC.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	A pointer to the VDAC peripheral register block.
const VDAC_Init_TypeDef *	[in]	init	A pointer to the VDAC initialization structure.

Initializes the common parts for both channels. This function will also load calibration values from the Device Information (DI) page into the VDAC calibration register. To complete a VDAC setup, channel control configuration must also be done. See VDAC_InitChannel().

Note

This function will disable both channels prior to configuration.

VDAC_InitChannel#

void VDAC_InitChannel (VDAC_TypeDef * vdac, const VDAC_InitChannel_TypeDef * init, unsigned int ch)

Initialize a VDAC channel.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	A pointer to the VDAC peripheral register block.
const VDAC_InitChannel_TypeDef *	[in]	init	A pointer to the VDAC channel initialization structure.
unsigned int	[in]	ch	A channel number to initialize.

VDAC_Channel0OutputSet#

void VDAC_Channel0OutputSet (VDAC_TypeDef * vdac, uint32_t value)

Set the output signal of VDAC channel 0 to a given value.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	value	Value to write to channel 0 output register CH0DATA.

This function sets the output signal of VDAC channel 0 by writing value to the CH0DATA register.

VDAC_Channel1OutputSet#

void VDAC_Channel1OutputSet (VDAC_TypeDef * vdac, uint32_t value)

Set the output signal of VDAC channel 1 to a given value.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	value	Value to write to channel 1 output register CH1DATA.

This function sets the output signal of VDAC channel 1 by writing value to the CH1DATA register.

VDAC_IntClear#

void VDAC_IntClear (VDAC_TypeDef * vdac, uint32_t flags)

Clear one or more pending VDAC interrupts.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	flags	Pending VDAC interrupt source to clear. Use a bitwise logic OR combination of valid interrupt flags for the VDAC module (VDAC_IF_nnn).

VDAC_IntDisable#

void VDAC_IntDisable (VDAC_TypeDef * vdac, uint32_t flags)

Disable one or more VDAC interrupts.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	flags	VDAC interrupt sources to disable. Use a bitwise logic OR combination of valid interrupt flags for the VDAC module (VDAC_IF_nnn).

VDAC_IntEnable#

void VDAC_IntEnable (VDAC_TypeDef * vdac, uint32_t flags)

Enable one or more VDAC interrupts.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	flags	VDAC interrupt sources to enable. Use a bitwise logic OR combination of valid interrupt flags for the VDAC module (VDAC_IF_nnn).

Note

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

VDAC_IntGet#

uint32_t VDAC_IntGet (VDAC_TypeDef * vdac)

Get pending VDAC interrupt flags.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.

Note

The event bits are not cleared by the use of this function.

Returns

VDAC interrupt sources pending. Use a bitwise logic OR combination of valid interrupt flags for the VDAC module (VDAC_IF_nnn).

VDAC_IntGetEnabled#

uint32_t VDAC_IntGetEnabled (VDAC_TypeDef * vdac)

Get enabled and pending VDAC interrupt flags.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.

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 VDAC interrupt sources. The return value is the bitwise AND combination of
- the OR combination of enabled interrupt sources in VDACx_IEN_nnn register (VDACx_IEN_nnn) and
- the OR combination of valid interrupt flags of the VDAC module (VDACx_IF_nnn).

VDAC_IntSet#

void VDAC_IntSet (VDAC_TypeDef * vdac, uint32_t flags)

Set one or more pending VDAC interrupts from SW.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	Pointer to VDAC peripheral register block.
uint32_t	[in]	flags	VDAC interrupt sources to set to pending. Use a bitwise logic OR combination of valid interrupt flags for the VDAC module (VDAC_IF_nnn).

VDAC_PrescaleCalc#

uint32_t VDAC_PrescaleCalc (uint32_t vdacFreq, bool syncMode, uint32_t hfperFreq)

Calculate the prescaler value used to determine VDAC clock.

Parameters

Type	Direction	Argument Name	Description
uint32_t	[in]	vdacFreq	VDAC frequency target. The frequency will automatically be adjusted to be below maximum allowed VDAC clock.
bool	[in]	syncMode	Set to true if you intend to use VDAC in synchronous mode.
uint32_t	[in]	hfperFreq	Frequency in Hz of HFPERCLK/HFPERCCLK oscillator. Set to 0 to use the currently defined HFPERCLK/HFPERCCLK clock setting. This parameter is only used when syncMode is set to true.

The VDAC clock is given by the input clock divided by the prescaler+1.

VDAC_CLK = IN_CLK / (prescale + 1)

The maximum VDAC clock is 1 MHz. The input clock is HFPERCLK/HFPERCCLK when VDAC synchronous mode is selected, or an internal oscillator of 10 MHz +/- 20% when asynchronous mode is selected.

Note

If the requested VDAC frequency is low and the maximum prescaler value can't adjust the actual VDAC frequency lower than requested, the maximum prescaler value is returned resulting in a higher VDAC frequency than requested.

Returns

A prescaler value to use for VDAC to achieve a clock value less than or equal to vdacFreq.

VDAC_Reset#

void VDAC_Reset (VDAC_TypeDef * vdac)

Reset VDAC to same state that it was in after a hardwares reset.

Parameters

Type	Direction	Argument Name	Description
VDAC_TypeDef *	[in]	vdac	A pointer to the VDAC peripheral register block.