Overview

The MCUXpresso SDK provides a peripheral driver for the Quadrature Encoder/Decoder (ENC) module of MCUXpresso SDK devices.

This section describes the programming interface of the ENC Peripheral driver. The ENC driver configures the ENC module and provides a functional interface for the user to build the ENC application.

Function groups

Initialization and De-initialization

This function group initializes default configuration structure for the ENC counter and initializes ENC counter with the normal configuration and de-initialize ENC module. Some APIs are also created to control the features.

Status

This function group get/clear the ENC status.

Interrupts

This function group enable/disable the ENC interrupts.

Value Operation

This function group get the counter/hold value of positions.

Typical use case

Polling Configuration

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/enc

Data Structures
struct	enc_config_t
	Define user configuration structure for ENC module. More...

struct	enc_self_test_config_t
	Define configuration structure for self test module. More...

Enumerations
enum	_enc_interrupt_enable { kENC_HOMETransitionInterruptEnable = (1U << 0U), kENC_INDEXPulseInterruptEnable = (1U << 1U), kENC_WatchdogTimeoutInterruptEnable = (1U << 2U), kENC_PositionCompareInerruptEnable = (1U << 3U), kENC_SimultBothPhaseChangeInterruptEnable, kENC_PositionRollOverInterruptEnable = (1U << 5U), kENC_PositionRollUnderInterruptEnable = (1U << 6U) }
	Interrupt enable/disable mask. More...

enum	_enc_status_flags { kENC_HOMETransitionFlag = (1U << 0U), kENC_INDEXPulseFlag = (1U << 1U), kENC_WatchdogTimeoutFlag = (1U << 2U), kENC_PositionCompareFlag = (1U << 3U), kENC_SimultBothPhaseChangeFlag = (1U << 4U), kENC_PositionRollOverFlag = (1U << 5U), kENC_PositionRollUnderFlag = (1U << 6U), kENC_LastCountDirectionFlag = (1U << 7U) }
	Status flag mask. More...

enum	_enc_signal_status_flags { kENC_RawHOMEStatusFlag = ENC_IMR_HOME_MASK, kENC_RawINDEXStatusFlag = ENC_IMR_INDEX_MASK, kENC_RawPHBStatusFlag = ENC_IMR_PHB_MASK, kENC_RawPHAEXStatusFlag = ENC_IMR_PHA_MASK, kENC_FilteredHOMEStatusFlag = ENC_IMR_FHOM_MASK, kENC_FilteredINDEXStatusFlag = ENC_IMR_FIND_MASK, kENC_FilteredPHBStatusFlag = ENC_IMR_FPHB_MASK, kENC_FilteredPHAStatusFlag = ENC_IMR_FPHA_MASK }
	Signal status flag mask. More...

enum	enc_home_trigger_mode_t { kENC_HOMETriggerDisabled = 0U, kENC_HOMETriggerOnRisingEdge, kENC_HOMETriggerOnFallingEdge }
	Define HOME signal's trigger mode. More...

enum	enc_index_trigger_mode_t { kENC_INDEXTriggerDisabled = 0U, kENC_INDEXTriggerOnRisingEdge, kENC_INDEXTriggerOnFallingEdge }
	Define INDEX signal's trigger mode. More...

enum	enc_decoder_work_mode_t { kENC_DecoderWorkAsNormalMode = 0U, kENC_DecoderWorkAsSignalPhaseCountMode }
	Define type for decoder work mode. More...

enum	enc_position_match_mode_t { kENC_POSMATCHOnPositionCounterEqualToComapreValue = 0U, kENC_POSMATCHOnReadingAnyPositionCounter }
	Define type for the condition of POSMATCH pulses. More...

enum	enc_revolution_count_condition_t { kENC_RevolutionCountOnINDEXPulse = 0U, kENC_RevolutionCountOnRollOverModulus }
	Define type for determining how the revolution counter (REV) is incremented/decremented. More...

enum	enc_self_test_direction_t { kENC_SelfTestDirectionPositive = 0U, kENC_SelfTestDirectionNegative }
	Define type for direction of self test generated signal. More...

Initialization and De-initialization
void	ENC_Init (ENC_Type base, const enc_config_t config)
	Initialization for the ENC module. More...

void	ENC_Deinit (ENC_Type *base)
	De-initialization for the ENC module. More...

void	ENC_GetDefaultConfig (enc_config_t *config)
	Get an available pre-defined settings for ENC's configuration. More...

void	ENC_DoSoftwareLoadInitialPositionValue (ENC_Type *base)
	Load the initial position value to position counter. More...

void	ENC_SetSelfTestConfig (ENC_Type base, const enc_self_test_config_t config)
	Enable and configure the self test function. More...

void	ENC_EnableWatchdog (ENC_Type *base, bool enable)
	Enable watchdog for ENC module. More...

void	ENC_SetInitialPositionValue (ENC_Type *base, uint32_t value)
	Set initial position value for ENC module. More...

Status
uint32_t	ENC_GetStatusFlags (ENC_Type *base)
	Get the status flags. More...

void	ENC_ClearStatusFlags (ENC_Type *base, uint32_t mask)
	Clear the status flags. More...

static uint16_t	ENC_GetSignalStatusFlags (ENC_Type *base)
	Get the signals' real-time status. More...

Interrupts
void	ENC_EnableInterrupts (ENC_Type *base, uint32_t mask)
	Enable the interrupts. More...

void	ENC_DisableInterrupts (ENC_Type *base, uint32_t mask)
	Disable the interrupts. More...

uint32_t	ENC_GetEnabledInterrupts (ENC_Type *base)
	Get the enabled interrupts' flags. More...

Value Operation
uint32_t	ENC_GetPositionValue (ENC_Type *base)
	Get the current position counter's value. More...

uint32_t	ENC_GetHoldPositionValue (ENC_Type *base)
	Get the hold position counter's value. More...

static uint16_t	ENC_GetPositionDifferenceValue (ENC_Type *base)
	Get the position difference counter's value. More...

static uint16_t	ENC_GetHoldPositionDifferenceValue (ENC_Type *base)
	Get the hold position difference counter's value. More...

static uint16_t	ENC_GetRevolutionValue (ENC_Type *base)
	Get the position revolution counter's value. More...

static uint16_t	ENC_GetHoldRevolutionValue (ENC_Type *base)
	Get the hold position revolution counter's value. More...

Data Structure Documentation

struct enc_config_t

Data Fields
bool	enableReverseDirection
	Enable reverse direction counting. More...

enc_decoder_work_mode_t	decoderWorkMode
	Enable signal phase count mode. More...

enc_home_trigger_mode_t	HOMETriggerMode
	Enable HOME to initialize position counters. More...

enc_index_trigger_mode_t	INDEXTriggerMode
	Enable INDEX to initialize position counters. More...

bool	enableTRIGGERClearPositionCounter
	Clear POSD, REV, UPOS and LPOS on rising edge of TRIGGER, or not. More...

bool	enableTRIGGERClearHoldPositionCounter
	Enable update of hold registers on rising edge of TRIGGER, or not.

bool	enableWatchdog
	Enable the watchdog to detect if the target is moving or not. More...

uint16_t	watchdogTimeoutValue
	Watchdog timeout count value. More...

uint16_t	filterCount
	Input Filter Sample Count. More...

uint16_t	filterSamplePeriod
	Input Filter Sample Period. More...

enc_position_match_mode_t	positionMatchMode
	The condition of POSMATCH pulses. More...

uint32_t	positionCompareValue
	Position compare value. More...

enc_revolution_count_condition_t	revolutionCountCondition
	Revolution Counter Modulus Enable. More...

bool	enableModuloCountMode
	Enable Modulo Counting. More...

uint32_t	positionModulusValue
	Position modulus value. More...

uint32_t	positionInitialValue
	Position initial value. More...

Field Documentation

bool enc_config_t::enableReverseDirection

enc_decoder_work_mode_t enc_config_t::decoderWorkMode

enc_home_trigger_mode_t enc_config_t::HOMETriggerMode

enc_index_trigger_mode_t enc_config_t::INDEXTriggerMode

bool enc_config_t::enableTRIGGERClearPositionCounter

bool enc_config_t::enableWatchdog

uint16_t enc_config_t::watchdogTimeoutValue

It stores the timeout count for the quadrature decoder module watchdog timer. This field is only available when "enableWatchdog" = true. The available value is a 16-bit unsigned number.

uint16_t enc_config_t::filterCount

This value should be chosen to reduce the probability of noisy samples causing an incorrect transition to be recognized. The value represent the number of consecutive samples that must agree prior to the input filter accepting an input transition. A value of 0x0 represents 3 samples. A value of 0x7 represents 10 samples. The Available range is 0 - 7.

uint16_t enc_config_t::filterSamplePeriod

This value should be set such that the sampling period is larger than the period of the expected noise. This value represents the sampling period (in IPBus clock cycles) of the decoder input signals. The available range is 0 - 255.

enc_position_match_mode_t enc_config_t::positionMatchMode

uint32_t enc_config_t::positionCompareValue

The available value is a 32-bit number.

enc_revolution_count_condition_t enc_config_t::revolutionCountCondition

bool enc_config_t::enableModuloCountMode

uint32_t enc_config_t::positionModulusValue

This value would be available only when "enableModuloCountMode" = true. The available value is a 32-bit number.

uint32_t enc_config_t::positionInitialValue

The available value is a 32-bit number.

struct enc_self_test_config_t

The self test module provides a quadrature test signal to the inputs of the quadrature decoder module. This is a factory test feature. It is also useful to customers' software development and testing.

Data Fields
enc_self_test_direction_t	signalDirection
	Direction of self test generated signal. More...

uint16_t	signalCount
	Hold the number of quadrature advances to generate. More...

uint16_t	signalPeriod
	Hold the period of quadrature phase in IPBus clock cycles. More...

Field Documentation

enc_self_test_direction_t enc_self_test_config_t::signalDirection

uint16_t enc_self_test_config_t::signalCount

The available range is 0 - 255.

uint16_t enc_self_test_config_t::signalPeriod

The available range is 0 - 31.

Enumeration Type Documentation

enum _enc_interrupt_enable

Enumerator
kENC_HOMETransitionInterruptEnable	HOME interrupt enable.
kENC_INDEXPulseInterruptEnable	INDEX pulse interrupt enable.
kENC_WatchdogTimeoutInterruptEnable	Watchdog timeout interrupt enable.
kENC_PositionCompareInerruptEnable	Position compare interrupt enable.
kENC_SimultBothPhaseChangeInterruptEnable	Simultaneous PHASEA and PHASEB change interrupt enable.
kENC_PositionRollOverInterruptEnable	Roll-over interrupt enable.
kENC_PositionRollUnderInterruptEnable	Roll-under interrupt enable.

enum _enc_status_flags

These flags indicate the counter's events.

Enumerator
kENC_HOMETransitionFlag	HOME signal transition interrupt request.
kENC_INDEXPulseFlag	INDEX Pulse Interrupt Request.
kENC_WatchdogTimeoutFlag	Watchdog timeout interrupt request.
kENC_PositionCompareFlag	Position compare interrupt request.
kENC_SimultBothPhaseChangeFlag	Simultaneous PHASEA and PHASEB change interrupt request.
kENC_PositionRollOverFlag	Roll-over interrupt request.
kENC_PositionRollUnderFlag	Roll-under interrupt request.
kENC_LastCountDirectionFlag	Last count was in the up direction, or the down direction.

enum _enc_signal_status_flags

These flags indicate the counter's signal.

Enumerator
kENC_RawHOMEStatusFlag	Raw HOME input.
kENC_RawINDEXStatusFlag	Raw INDEX input.
kENC_RawPHBStatusFlag	Raw PHASEB input.
kENC_RawPHAEXStatusFlag	Raw PHASEA input.
kENC_FilteredHOMEStatusFlag	The filtered version of HOME input.
kENC_FilteredINDEXStatusFlag	The filtered version of INDEX input.
kENC_FilteredPHBStatusFlag	The filtered version of PHASEB input.
kENC_FilteredPHAStatusFlag	The filtered version of PHASEA input.

enum enc_home_trigger_mode_t

The ENC would count the trigger from HOME signal line.

Enumerator
kENC_HOMETriggerDisabled	HOME signal's trigger is disabled.
kENC_HOMETriggerOnRisingEdge	Use positive going edge-to-trigger initialization of position counters.
kENC_HOMETriggerOnFallingEdge	Use negative going edge-to-trigger initialization of position counters.

enum enc_index_trigger_mode_t

The ENC would count the trigger from INDEX signal line.

Enumerator
kENC_INDEXTriggerDisabled	INDEX signal's trigger is disabled.
kENC_INDEXTriggerOnRisingEdge	Use positive going edge-to-trigger initialization of position counters.
kENC_INDEXTriggerOnFallingEdge	Use negative going edge-to-trigger initialization of position counters.

enum enc_decoder_work_mode_t

The normal work mode uses the standard quadrature decoder with PHASEA and PHASEB. When in signal phase count mode, a positive transition of the PHASEA input generates a count signal while the PHASEB input and the reverse direction control the counter direction. If the reverse direction is not enabled, PHASEB = 0 means counting up and PHASEB = 1 means counting down. Otherwise, the direction is reversed.

Enumerator
kENC_DecoderWorkAsNormalMode	Use standard quadrature decoder with PHASEA and PHASEB.
kENC_DecoderWorkAsSignalPhaseCountMode	PHASEA input generates a count signal while PHASEB input control the direction.

enum enc_position_match_mode_t

Enumerator
kENC_POSMATCHOnPositionCounterEqualToComapreValue	POSMATCH pulses when a match occurs between the position counters (POS) and the compare value (COMP).
kENC_POSMATCHOnReadingAnyPositionCounter	POSMATCH pulses when any position counter register is read.

enum enc_revolution_count_condition_t

Enumerator
kENC_RevolutionCountOnINDEXPulse	Use INDEX pulse to increment/decrement revolution counter.
kENC_RevolutionCountOnRollOverModulus	Use modulus counting roll-over/under to increment/decrement revolution counter.

enum enc_self_test_direction_t

Enumerator
kENC_SelfTestDirectionPositive	Self test generates the signal in positive direction.
kENC_SelfTestDirectionNegative	Self test generates the signal in negative direction.

Function Documentation

void ENC_Init	(	ENC_Type *	base,
		const enc_config_t *	config
	)

This function is to make the initialization for the ENC module. It should be called firstly before any operation to the ENC with the operations like:

Enable the clock for ENC module.
Configure the ENC's working attributes.

Parameters

base	ENC peripheral base address.
config	Pointer to configuration structure. See to "enc_config_t".

void ENC_Deinit ( ENC_Type * base )

This function is to make the de-initialization for the ENC module. It could be called when ENC is no longer used with the operations like:

Disable the clock for ENC module.

Parameters

base	ENC peripheral base address.

void ENC_GetDefaultConfig ( enc_config_t * config )

This function initializes the ENC configuration structure with an available settings, the default value are:

*   config->enableReverseDirection                = false;
*   config->decoderWorkMode                       = kENC_DecoderWorkAsNormalMode;
*   config->HOMETriggerMode                       = kENC_HOMETriggerDisabled;
*   config->INDEXTriggerMode                      = kENC_INDEXTriggerDisabled;
*   config->enableTRIGGERClearPositionCounter     = false;
*   config->enableTRIGGERClearHoldPositionCounter = false;
*   config->enableWatchdog                        = false;
*   config->watchdogTimeoutValue                  = 0U;
*   config->filterCount                           = 0U;
*   config->filterSamplePeriod                    = 0U;
*   config->positionMatchMode                     = kENC_POSMATCHOnPositionCounterEqualToComapreValue;
*   config->positionCompareValue                  = 0xFFFFFFFFU;
*   config->revolutionCountCondition              = kENC_RevolutionCountOnINDEXPulse;
*   config->enableModuloCountMode                 = false;
*   config->positionModulusValue                  = 0U;
*   config->positionInitialValue                  = 0U;
* 

Parameters

config Pointer to a variable of configuration structure. See to "enc_config_t".

void ENC_DoSoftwareLoadInitialPositionValue ( ENC_Type * base )

This function is to transfer the initial position value (UINIT and LINIT) contents to position counter (UPOS and LPOS), so that to provide the consistent operation the position counter registers.

Parameters

base	ENC peripheral base address.

void ENC_SetSelfTestConfig	(	ENC_Type *	base,
		const enc_self_test_config_t *	config
	)

This function is to enable and configuration the self test function. It controls and sets the frequency of a quadrature signal generator. It provides a quadrature test signal to the inputs of the quadrature decoder module. It is a factory test feature; however, it may be useful to customers' software development and testing.

Parameters

base	ENC peripheral base address.
config	Pointer to configuration structure. See to "enc_self_test_config_t". Pass "NULL" to disable.

void ENC_EnableWatchdog	(	ENC_Type *	base,
		bool	enable
	)

Parameters

base	ENC peripheral base address
enable	Enables or disables the watchdog

void ENC_SetInitialPositionValue	(	ENC_Type *	base,
		uint32_t	value
	)

Parameters

base	ENC peripheral base address
value	Positive initial value

uint32_t ENC_GetStatusFlags ( ENC_Type * base )

Parameters

base	ENC peripheral base address.

Returns: Mask value of status flags. For available mask, see to "_enc_status_flags".

void ENC_ClearStatusFlags	(	ENC_Type *	base,
		uint32_t	mask
	)

Parameters

base	ENC peripheral base address.
mask	Mask value of status flags to be cleared. For available mask, see to "_enc_status_flags".

static uint16_t ENC_GetSignalStatusFlags ( ENC_Type * base )

inlinestatic

Parameters

base	ENC peripheral base address.

Returns: Mask value of signals' real-time status. For available mask, see to "_enc_signal_status_flags"

void ENC_EnableInterrupts	(	ENC_Type *	base,
		uint32_t	mask
	)

Parameters

base	ENC peripheral base address.
mask	Mask value of interrupts to be enabled. For available mask, see to "_enc_interrupt_enable".

void ENC_DisableInterrupts	(	ENC_Type *	base,
		uint32_t	mask
	)

Parameters

base	ENC peripheral base address.
mask	Mask value of interrupts to be disabled. For available mask, see to "_enc_interrupt_enable".

uint32_t ENC_GetEnabledInterrupts ( ENC_Type * base )

Parameters

base	ENC peripheral base address.

Returns: Mask value of enabled interrupts.

uint32_t ENC_GetPositionValue ( ENC_Type * base )

Parameters

base	ENC peripheral base address.

Returns: Current position counter's value.

uint32_t ENC_GetHoldPositionValue ( ENC_Type * base )

When any of the counter registers is read, the contents of each counter register is written to the corresponding hold register. Taking a snapshot of the counters' values provides a consistent view of a system position and a velocity to be attained.

Parameters

base	ENC peripheral base address.

Returns: Hold position counter's value.

static uint16_t ENC_GetPositionDifferenceValue ( ENC_Type * base )

inlinestatic

Parameters

base	ENC peripheral base address.

Returns: The position difference counter's value.

static uint16_t ENC_GetHoldPositionDifferenceValue ( ENC_Type * base )

inlinestatic

When any of the counter registers is read, the contents of each counter register is written to the corresponding hold register. Taking a snapshot of the counters' values provides a consistent view of a system position and a velocity to be attained.

Parameters

base	ENC peripheral base address.

Returns: Hold position difference counter's value.

static uint16_t ENC_GetRevolutionValue ( ENC_Type * base )

inlinestatic

Parameters

base	ENC peripheral base address.

Returns: The position revolution counter's value.

static uint16_t ENC_GetHoldRevolutionValue ( ENC_Type * base )

inlinestatic

When any of the counter registers is read, the contents of each counter register is written to the corresponding hold register. Taking a snapshot of the counters' values provides a consistent view of a system position and a velocity to be attained.

Parameters

base	ENC peripheral base address.

Returns: Hold position revolution counter's value.

Overview

Function groups

Initialization and De-initialization

Status

Interrupts

Value Operation

Typical use case

Polling Configuration

Data Structures

Enumerations

Initialization and De-initialization

Status

Interrupts

Value Operation

Data Structure Documentation

Data Fields

Field Documentation

Data Fields

Field Documentation

Enumeration Type Documentation

Function Documentation