PCNT - Pulse Counter#

Pulse Counter (PCNT) Peripheral API.

This module contains functions to control the PCNT peripheral of Silicon Labs 32-bit MCUs and SoCs. The PCNT decodes incoming pulses. The module has a quadrature mode which may be used to decode the speed and direction of a mechanical shaft.

Modules#

PCNT_Init_TypeDef

PCNT_Filter_TypeDef

Enumerations#

enum
pcntModeDisable = PCNT_MODE_DISABLE
pcntModeOvsSingle = _PCNT_CFG_MODE_OVSSINGLE
pcntModeExtSingle = _PCNT_CFG_MODE_EXTCLKSINGLE
pcntModeExtQuad = _PCNT_CFG_MODE_EXTCLKQUAD
pcntModeOvsQuad1 = _PCNT_CFG_MODE_OVSQUAD1X
pcntModeOvsQuad2 = _PCNT_CFG_MODE_OVSQUAD2X
pcntModeOvsQuad4 = _PCNT_CFG_MODE_OVSQUAD4X
}

Mode selection.

enum
pcntCntEventBoth = _PCNT_CTRL_CNTEV_BOTH
pcntCntEventUp = _PCNT_CTRL_CNTEV_UP
pcntCntEventDown = _PCNT_CTRL_CNTEV_DOWN
pcntCntEventNone = PCNT_CNT_EVENT_NONE
}

Counter event selection.

enum
pcntPRSInputS0 = 0
pcntPRSInputS1 = 1
}

PRS inputs of PCNT.

Typedefs#

typedef unsigned int

PRS sources for s0PRS and s1PRS.

Functions#

void
PCNT_CounterReset(PCNT_TypeDef *pcnt)

Reset PCNT counters and TOP register.

void
PCNT_Enable(PCNT_TypeDef *pcnt, PCNT_Mode_TypeDef mode)

Set PCNT operational mode.

bool
PCNT_IsEnabled(PCNT_TypeDef *pcnt)

Returns if the PCNT module is enabled or not.

void
PCNT_CounterTopSet(PCNT_TypeDef *pcnt, uint32_t count, uint32_t top)

Set the counter and top values.

void
PCNT_PRSInputEnable(PCNT_TypeDef *pcnt, PCNT_PRSInput_TypeDef prsInput, bool enable)

Enable/disable the selected PRS input of PCNT.

void
PCNT_Init(PCNT_TypeDef *pcnt, const PCNT_Init_TypeDef *init)

Initialize the pulse counter.

void
PCNT_Reset(PCNT_TypeDef *pcnt)

Reset PCNT to the same state that it was in after a hardware reset.

void
PCNT_FilterConfiguration(PCNT_TypeDef *pcnt, const PCNT_Filter_TypeDef *config, bool enable)

Set the filter configuration.

void
PCNT_TopBufferSet(PCNT_TypeDef *pcnt, uint32_t val)

Set top buffer value.

void
PCNT_TopSet(PCNT_TypeDef *pcnt, uint32_t val)

Set the top value.

uint32_t
PCNT_CounterGet(PCNT_TypeDef *pcnt)

Get the pulse counter value.

uint32_t
PCNT_AuxCounterGet(PCNT_TypeDef *pcnt)

Get the auxiliary counter value.

void
PCNT_CounterSet(PCNT_TypeDef *pcnt, uint32_t count)

Set a counter value.

void
PCNT_IntClear(PCNT_TypeDef *pcnt, uint32_t flags)

Clear one or more pending PCNT interrupts.

void
PCNT_IntDisable(PCNT_TypeDef *pcnt, uint32_t flags)

Disable one or more PCNT interrupts.

void
PCNT_IntEnable(PCNT_TypeDef *pcnt, uint32_t flags)

Enable one or more PCNT interrupts.

uint32_t
PCNT_IntGet(PCNT_TypeDef *pcnt)

Get pending PCNT interrupt flags.

uint32_t
PCNT_IntGetEnabled(PCNT_TypeDef *pcnt)

Get enabled and pending PCNT interrupt flags.

void
PCNT_IntSet(PCNT_TypeDef *pcnt, uint32_t flags)

Set one or more pending PCNT interrupts from SW.

void
PCNT_Lock(PCNT_TypeDef *pcnt)

Lock PCNT registers.

void
PCNT_Unlock(PCNT_TypeDef *pcnt)

Unlock PCNT registers.

uint32_t
PCNT_TopBufferGet(PCNT_TypeDef *pcnt)

Get the pulse counter top buffer value.

uint32_t
PCNT_TopGet(PCNT_TypeDef *pcnt)

Get the pulse counter top value.

void
PCNT_Sync(PCNT_TypeDef *pcnt, uint32_t mask)

Wait for an ongoing sync of register(s) to low-frequency domain to complete.

void
PCNT_StartMainCnt(PCNT_TypeDef *pcnt)

Start the main PCNT counter.

void
PCNT_StopMainCnt(PCNT_TypeDef *pcnt)

Stop the main PCNT counter.

void
PCNT_StartAuxCnt(PCNT_TypeDef *pcnt)

Start the auxiliary PCNT counter.

void
PCNT_StopAuxCnt(PCNT_TypeDef *pcnt)

Stop the auxiliary PCNT counter.

Macros#

#define
PCNT0_CNT_SIZE (16)

PCNT0 Counter register size.

#define
PCNT_MODE_DISABLE 0xFF

PCNT mode disable.

#define
PCNT_CNT_EVENT_NONE 0xFF

PCNT count event is none.

#define
DEFAULT_DEBUG_HALT true,

Default Debug.

#define
DEFAULT_MODE pcntModeDisable,

Default Mode.

#define
DEFAULT_HYST false,

Default Hysteresis.

#define
DEFAULT_CDIR true,

Default counter direction.

#define
DEFAULT_CNTEV pcntCntEventUp,

Default count event.

#define
DEFAULT_AUXCNTEV pcntCntEventNone,

Default auxiliary count event.

#define
DEFAULT_PRS_CH 0u,

Default selected PRS channel as S0IN and S1IN.

#define
PCNT_INIT_DEFAULT undefined

Default configuration for PCNT initialization structure.

#define
PCNT_FILTER_DEFAULT undefined

Default configuration for PCNT initialization structure.

Enumeration Documentation#

PCNT_Mode_TypeDef#

PCNT_Mode_TypeDef

Mode selection.

Enumerator
pcntModeDisable

Disable pulse counter.

pcntModeOvsSingle

Single input LFACLK oversampling mode (available in EM0-EM2).

pcntModeExtSingle

Externally clocked single input counter mode (available in EM0-EM3).

pcntModeExtQuad

Externally clocked quadrature decoder mode (available in EM0-EM3).

pcntModeOvsQuad1

LFACLK oversampling quadrature decoder 1X mode (available in EM0-EM2).

pcntModeOvsQuad2

LFACLK oversampling quadrature decoder 2X mode (available in EM0-EM2).

pcntModeOvsQuad4

LFACLK oversampling quadrature decoder 4X mode (available in EM0-EM2).


PCNT_CntEvent_TypeDef#

PCNT_CntEvent_TypeDef

Counter event selection.

Note: unshifted values are being used for enumeration because multiple configuration structure members use this type definition.

Enumerator
pcntCntEventBoth

Counts up on up-count and down on down-count events.

pcntCntEventUp

Only counts up on up-count events.

pcntCntEventDown

Only counts down on down-count events.

pcntCntEventNone

Never counts.


PCNT_PRSInput_TypeDef#

PCNT_PRSInput_TypeDef

PRS inputs of PCNT.

Enumerator
pcntPRSInputS0
pcntPRSInputS1

PRS input 0.


Typedef Documentation#

PCNT_PRSSel_TypeDef#

typedef unsigned int PCNT_PRSSel_TypeDef

PRS sources for s0PRS and s1PRS.


Variable Documentation#

initCntEvent#

PCNT_CntEvent_TypeDef initCntEvent

initAuxCntEvent#

PCNT_CntEvent_TypeDef initAuxCntEvent

Function Documentation#

PCNT_CounterReset#

void PCNT_CounterReset (PCNT_TypeDef * pcnt)

Reset PCNT counters and TOP register.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

Note

  • Notice that special SYNCBUSY handling is not applicable for the RSTEN bit of the control register, so we don't need to wait for it when only modifying RSTEN. (It would mean undefined wait time if clocked by an external clock.) The SYNCBUSY bit will however be set, leading to a synchronization in the LF domain, with, in reality, no changes.


PCNT_Enable#

void PCNT_Enable (PCNT_TypeDef * pcnt, PCNT_Mode_TypeDef mode)

Set PCNT operational mode.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

PCNT_Mode_TypeDef[in]mode

An operational mode to use for PCNT.

Notice that this function does not do any configuration. Setting operational mode is normally only required after initialization is done, and if not done as part of initialization or if requiring to disable/reenable pulse counter.

Note

  • This function may stall until synchronization to low-frequency domain is completed. For that reason, it should normally not be used when an external clock is used for the PCNT module, since stall time may be undefined.


PCNT_IsEnabled#

bool PCNT_IsEnabled (PCNT_TypeDef * pcnt)

Returns if the PCNT module is enabled or not.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

Notice that this function does not do any configuration.

Returns

  • Returns TRUE if the module is enabled.


PCNT_CounterTopSet#

void PCNT_CounterTopSet (PCNT_TypeDef * pcnt, uint32_t count, uint32_t top)

Set the counter and top values.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

uint32_t[in]count

A value to set in the counter register.

uint32_t[in]top

A value to set in the top register.

The pulse counter is disabled while changing these values and reenabled (if originally enabled) when values have been set.

Note

  • This function will stall until synchronization to low-frequency domain is completed. For that reason, it should normally not be used when an external clock is used for the PCNT module, since stall time may be undefined. The counter should normally only be set when operating in (or about to enable) pcntModeOvsSingle mode.


PCNT_PRSInputEnable#

void PCNT_PRSInputEnable (PCNT_TypeDef * pcnt, PCNT_PRSInput_TypeDef prsInput, bool enable)

Enable/disable the selected PRS input of PCNT.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

PCNT_PRSInput_TypeDef[in]prsInput

PRS input (S0 or S1) of the selected PCNT module.

bool[in]enable

Set to true to enable, false to disable the selected PRS input.

Notice that this function does not do any configuration.


PCNT_Init#

void PCNT_Init (PCNT_TypeDef * pcnt, const PCNT_Init_TypeDef * init)

Initialize the pulse counter.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

const PCNT_Init_TypeDef *[in]init

A pointer to the initialization structure.

This function will configure the pulse counter. The clock selection is configured as follows, depending on operational mode:

Notice that the LFACLK must be enabled in all modes, since some basic setup is done with this clock even if the external pin clock usage mode is chosen. The pulse counter clock for the selected instance must also be enabled prior to initialization.

Notice that pins used by the PCNT module must be properly configured by the user explicitly through setting the ROUTE register for the PCNT to work as intended.

Writing to CNT will not occur in external clock modes (EXTCLKQUAD and EXTCLKSINGLE) because the external clock rate is unknown. The user should handle it manually depending on the application.

TOPB is written for all modes but in external clock mode it will take 3 external clock cycles to sync to TOP.

Note

  • Initializing requires synchronization into the low-frequency domain. This may cause a delay.


PCNT_Reset#

void PCNT_Reset (PCNT_TypeDef * pcnt)

Reset PCNT to the same state that it was in after a hardware reset.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

Notice the LFACLK must be enabled, since some basic reset is done with this clock. The pulse counter clock for the selected instance must also be enabled prior to initialization.

Note

  • The ROUTE register is NOT reset by this function to allow for centralized setup of this feature.


PCNT_FilterConfiguration#

void PCNT_FilterConfiguration (PCNT_TypeDef * pcnt, const PCNT_Filter_TypeDef * config, bool enable)

Set the filter configuration.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

const PCNT_Filter_TypeDef *[in]config

A pointer to the configuration structure to be applied.

bool[in]enable

Indicates whether to enable or disable filtering.

This function will configure the PCNT input filter when the PCNT mode is configured to take an LFA-derived clock as an input clock.


PCNT_TopBufferSet#

void PCNT_TopBufferSet (PCNT_TypeDef * pcnt, uint32_t val)

Set top buffer value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

uint32_t[in]val

A value to set in the top buffer register.

Note

  • This function may stall until synchronization to low-frequency domain is completed. For that reason, it should normally not be used when an external clock is used for the PCNT module since stall time may be undefined.


PCNT_TopSet#

void PCNT_TopSet (PCNT_TypeDef * pcnt, uint32_t val)

Set the top value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

uint32_t[in]val

A value to set in the top register.

Note

  • This function will stall until synchronization to low-frequency domain is completed. For that reason, it should normally not be used when an external clock is used for the PCNT module since stall time may be undefined.


PCNT_CounterGet#

uint32_t PCNT_CounterGet (PCNT_TypeDef * pcnt)

Get the pulse counter value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Returns

  • Current pulse counter value.


PCNT_AuxCounterGet#

uint32_t PCNT_AuxCounterGet (PCNT_TypeDef * pcnt)

Get the auxiliary counter value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Returns

  • Current auxiliary counter value.


PCNT_CounterSet#

void PCNT_CounterSet (PCNT_TypeDef * pcnt, uint32_t count)

Set a counter value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

uint32_t[in]count

Value to set in counter register.

Pulse counter is disabled while changing counter value and re-enabled (if originally enabled) when counter value has been set.

Note

  • This function will stall until synchronization to low-frequency domain is completed. For that reason, it should normally not be used when using an external clock to clock the PCNT module since stall time may be undefined in that case. The counter should normally only be set when operating in (or about to enable) pcntModeOvsSingle mode.


PCNT_IntClear#

void PCNT_IntClear (PCNT_TypeDef * pcnt, uint32_t flags)

Clear one or more pending PCNT interrupts.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

uint32_t[in]flags

Pending PCNT interrupt source to clear. Use a bitwise logic OR combination of valid interrupt flags for the PCNT module (PCNT_IF_nnn).


PCNT_IntDisable#

void PCNT_IntDisable (PCNT_TypeDef * pcnt, uint32_t flags)

Disable one or more PCNT interrupts.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

uint32_t[in]flags

PCNT interrupt sources to disable. Use a bitwise logic OR combination of valid interrupt flags for PCNT module (PCNT_IF_nnn).


PCNT_IntEnable#

void PCNT_IntEnable (PCNT_TypeDef * pcnt, uint32_t flags)

Enable one or more PCNT interrupts.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

uint32_t[in]flags

PCNT interrupt sources to enable. Use a bitwise logic OR combination of valid interrupt flags for PCNT module (PCNT_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 PCNT_IntClear() prior to enabling the interrupt.


PCNT_IntGet#

uint32_t PCNT_IntGet (PCNT_TypeDef * pcnt)

Get pending PCNT interrupt flags.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Note

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

Returns

  • PCNT interrupt sources pending. A bitwise logic OR combination of valid interrupt flags for PCNT module (PCNT_IF_nnn).


PCNT_IntGetEnabled#

uint32_t PCNT_IntGetEnabled (PCNT_TypeDef * pcnt)

Get enabled and pending PCNT interrupt flags.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to thePCNT peripheral register block.

Useful for handling more interrupt sources in the same interrupt handler.

Note

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

Returns

  • Pending and enabled PCNT interrupt sources. The return value is the bitwise AND combination of

    • the OR combination of enabled interrupt sources in PCNT_IEN_nnn register (PCNT_IEN_nnn) and

    • the OR combination of valid interrupt flags of the PCNT module (PCNT_IF_nnn).


PCNT_IntSet#

void PCNT_IntSet (PCNT_TypeDef * pcnt, uint32_t flags)

Set one or more pending PCNT interrupts from SW.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

uint32_t[in]flags

PCNT interrupt sources to set to pending. Use a bitwise logic OR combination of valid interrupt flags for PCNT module (PCNT_IF_nnn).


PCNT_Lock#

void PCNT_Lock (PCNT_TypeDef * pcnt)

Lock PCNT registers.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Note

  • When PCNT registers are locked PCNT_CFG, PCNT_EN, PCNT_SWRST, PCNT_CMD, PCNT_CTRL, PCNT_OVSCTRL, PCNT_CNT, PCNT_TOP, and PCNT_TOPB registers cannot be written to.


PCNT_Unlock#

void PCNT_Unlock (PCNT_TypeDef * pcnt)

Unlock PCNT registers.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to thePCNT peripheral register block.


PCNT_TopBufferGet#

uint32_t PCNT_TopBufferGet (PCNT_TypeDef * pcnt)

Get the pulse counter top buffer value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Returns

  • Current pulse counter top buffer value.


PCNT_TopGet#

uint32_t PCNT_TopGet (PCNT_TypeDef * pcnt)

Get the pulse counter top value.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

Pointer to the PCNT peripheral register block.

Returns

  • Current pulse counter top value.


PCNT_Sync#

void PCNT_Sync (PCNT_TypeDef * pcnt, uint32_t mask)

Wait for an ongoing sync of register(s) to low-frequency domain to complete.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

uint32_t[in]mask

A bitmask corresponding to SYNCBUSY register defined bits indicating registers that must complete any ongoing synchronization.


PCNT_StartMainCnt#

void PCNT_StartMainCnt (PCNT_TypeDef * pcnt)

Start the main PCNT counter.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

This function will send a start command to the PCNT peripheral. The PCNT peripheral will use some LF clock ticks before the command is executed. The PCNT_Sync() function can be used to wait for the start command to be executed.

Note

  • This function requires the PCNT to be enabled.


PCNT_StopMainCnt#

void PCNT_StopMainCnt (PCNT_TypeDef * pcnt)

Stop the main PCNT counter.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

This function will send a stop command to the PCNT peripheral. The PCNT peripheral will use some LF clock ticks before the command is executed. The PCNT_Sync() function can be used to wait for the stop command to be executed.

Note

  • This function requires the PCNT to be enabled.


PCNT_StartAuxCnt#

void PCNT_StartAuxCnt (PCNT_TypeDef * pcnt)

Start the auxiliary PCNT counter.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

This function will send a start command to the PCNT peripheral. The PCNT peripheral will use some LF clock ticks before the command is executed. The PCNT_Sync() function can be used to wait for the start command to be executed.

Note

  • This function requires the PCNT to be enabled.


PCNT_StopAuxCnt#

void PCNT_StopAuxCnt (PCNT_TypeDef * pcnt)

Stop the auxiliary PCNT counter.

Parameters
TypeDirectionArgument NameDescription
PCNT_TypeDef *[in]pcnt

A pointer to the PCNT peripheral register block.

This function will send a stop command to the PCNT peripheral. The PCNT peripheral will use some LF clock ticks before the command is executed. The PCNT_Sync() function can be used to wait for the stop command to be executed.

Note

  • This function requires the PCNT to be enabled.