Class for counting the number of ticks on a digital input channel. More...

#include <frc/Counter.h>

Inheritance diagram for frc::Counter:

Public Types
enum	Mode { kTwoPulse = 0 , kSemiperiod = 1 , kPulseLength = 2 , kExternalDirection = 3 }

Public Types inherited from frc::CounterBase
enum	EncodingType { k1X , k2X , k4X }

Public Member Functions
	Counter (Mode mode=kTwoPulse)
	Create an instance of a counter where no sources are selected. More...

	Counter (int channel)
	Create an instance of a Counter object. More...

	Counter (DigitalSource *source)
	Create an instance of a counter from a Digital Source (such as a Digital Input). More...

	Counter (std::shared_ptr< DigitalSource > source)
	Create an instance of a counter from a Digital Source (such as a Digital Input). More...

	Counter (const AnalogTrigger &trigger)
	Create an instance of a Counter object. More...

	Counter (EncodingType encodingType, DigitalSource upSource, DigitalSource downSource, bool inverted)
	Create an instance of a Counter object. More...

	Counter (EncodingType encodingType, std::shared_ptr< DigitalSource > upSource, std::shared_ptr< DigitalSource > downSource, bool inverted)
	Create an instance of a Counter object. More...

	~Counter () override

	Counter (Counter &&)=default

Counter &	operator= (Counter &&)=default

void	SetUpSource (int channel)
	Set the upsource for the counter as a digital input channel. More...

void	SetUpSource (AnalogTrigger *analogTrigger, AnalogTriggerType triggerType)
	Set the up counting source to be an analog trigger. More...

void	SetUpSource (std::shared_ptr< AnalogTrigger > analogTrigger, AnalogTriggerType triggerType)
	Set the up counting source to be an analog trigger. More...

void	SetUpSource (DigitalSource *source)

void	SetUpSource (std::shared_ptr< DigitalSource > source)
	Set the source object that causes the counter to count up. More...

void	SetUpSource (DigitalSource &source)
	Set the source object that causes the counter to count up. More...

void	SetUpSourceEdge (bool risingEdge, bool fallingEdge)
	Set the edge sensitivity on an up counting source. More...

void	ClearUpSource ()
	Disable the up counting source to the counter. More...

void	SetDownSource (int channel)
	Set the down counting source to be a digital input channel. More...

void	SetDownSource (AnalogTrigger *analogTrigger, AnalogTriggerType triggerType)
	Set the down counting source to be an analog trigger. More...

void	SetDownSource (std::shared_ptr< AnalogTrigger > analogTrigger, AnalogTriggerType triggerType)
	Set the down counting source to be an analog trigger. More...

void	SetDownSource (DigitalSource *source)
	Set the source object that causes the counter to count down. More...

void	SetDownSource (DigitalSource &source)
	Set the source object that causes the counter to count down. More...

void	SetDownSource (std::shared_ptr< DigitalSource > source)

void	SetDownSourceEdge (bool risingEdge, bool fallingEdge)
	Set the edge sensitivity on a down counting source. More...

void	ClearDownSource ()
	Disable the down counting source to the counter. More...

void	SetUpDownCounterMode ()
	Set standard up / down counting mode on this counter. More...

void	SetExternalDirectionMode ()
	Set external direction mode on this counter. More...

void	SetSemiPeriodMode (bool highSemiPeriod)
	Set Semi-period mode on this counter. More...

void	SetPulseLengthMode (double threshold)
	Configure the counter to count in up or down based on the length of the input pulse. More...

void	SetReverseDirection (bool reverseDirection)
	Set the Counter to return reversed sensing on the direction. More...

void	SetSamplesToAverage (int samplesToAverage)
	Set the Samples to Average which specifies the number of samples of the timer to average when calculating the period. More...

int	GetSamplesToAverage () const
	Get the Samples to Average which specifies the number of samples of the timer to average when calculating the period. More...

int	GetFPGAIndex () const

void	SetDistancePerPulse (double distancePerPulse)
	Set the distance per pulse for this counter. More...

double	GetDistance () const
	Read the current scaled counter value. More...

double	GetRate () const
	Get the current rate of the Counter. More...

int	Get () const override
	Read the current counter value. More...

void	Reset () override
	Reset the Counter to zero. More...

units::second_t	GetPeriod () const override
	Get the Period of the most recent count. More...

void	SetMaxPeriod (units::second_t maxPeriod) final
	Set the maximum period where the device is still considered "moving". More...

void	SetUpdateWhenEmpty (bool enabled)
	Select whether you want to continue updating the event timer output when there are no samples captured. More...

bool	GetStopped () const override
	Determine if the clock is stopped. More...

bool	GetDirection () const override
	The last direction the counter value changed. More...

void	InitSendable (wpi::SendableBuilder &builder) override
	Initializes this Sendable object. More...

Public Member Functions inherited from frc::CounterBase
	CounterBase ()=default

virtual	~CounterBase ()=default

	CounterBase (CounterBase &&)=default

CounterBase &	operator= (CounterBase &&)=default

virtual int	Get () const =0

virtual void	Reset ()=0

virtual units::second_t	GetPeriod () const =0

virtual void	SetMaxPeriod (units::second_t maxPeriod)=0

virtual bool	GetStopped () const =0

virtual bool	GetDirection () const =0

Public Member Functions inherited from wpi::Sendable
virtual	~Sendable ()=default

virtual void	InitSendable (SendableBuilder &builder)=0
	Initializes this Sendable object. More...

Public Member Functions inherited from wpi::SendableHelper< Counter >
	SendableHelper (const SendableHelper &rhs)=default

	SendableHelper (SendableHelper &&rhs)

SendableHelper &	operator= (const SendableHelper &rhs)=default

SendableHelper &	operator= (SendableHelper &&rhs)

Protected Attributes
std::shared_ptr< DigitalSource >	m_upSource
	Makes the counter count up. More...

std::shared_ptr< DigitalSource >	m_downSource
	Makes the counter count down. More...

hal::Handle< HAL_CounterHandle >	m_counter
	The FPGA counter object. More...

Friends
class	DMA

class	DMASample

class	DigitalGlitchFilter

Additional Inherited Members
Protected Member Functions inherited from wpi::SendableHelper< Counter >
	SendableHelper ()=default

	~SendableHelper ()

Detailed Description

Class for counting the number of ticks on a digital input channel.

This is a general purpose class for counting repetitive events. It can return the number of counts, the period of the most recent cycle, and detect when the signal being counted has stopped by supplying a maximum cycle time.

All counters will immediately start counting - Reset() them if you need them to be zeroed before use.

Member Enumeration Documentation

◆ Mode

enum frc::Counter::Mode

Enumerator
kTwoPulse
kSemiperiod
kPulseLength
kExternalDirection

Constructor & Destructor Documentation

◆ Counter() [1/8]

frc::Counter::Counter ( Mode mode = kTwoPulse )

explicit

Create an instance of a counter where no sources are selected.

They all must be selected by calling functions to specify the upsource and the downsource independently.

This creates a ChipObject counter and initializes status variables appropriately.

The counter will start counting immediately.

Parameters

mode	The counter mode

◆ Counter() [2/8]

frc::Counter::Counter ( int channel )

explicit

Create an instance of a Counter object.

Create an up-Counter instance given a channel.

The counter will start counting immediately.

Parameters

channel The DIO channel to use as the up source. 0-9 are on-board, 10-25 are on the MXP

◆ Counter() [3/8]

frc::Counter::Counter ( DigitalSource * source )

explicit

Create an instance of a counter from a Digital Source (such as a Digital Input).

This is used if an existing digital input is to be shared by multiple other objects such as encoders or if the Digital Source is not a Digital Input channel (such as an Analog Trigger).

The counter will start counting immediately.

Parameters

source A pointer to the existing DigitalSource object. It will be set as the Up Source.

◆ Counter() [4/8]

frc::Counter::Counter ( std::shared_ptr< DigitalSource > source )

explicit

Create an instance of a counter from a Digital Source (such as a Digital Input).

This is used if an existing digital input is to be shared by multiple other objects such as encoders or if the Digital Source is not a Digital Input channel (such as an Analog Trigger).

The counter will start counting immediately.

Parameters

source A pointer to the existing DigitalSource object. It will be set as the Up Source.

◆ Counter() [5/8]

frc::Counter::Counter ( const AnalogTrigger & trigger )

explicit

Create an instance of a Counter object.

Create an instance of a simple up-Counter given an analog trigger. Use the trigger state output from the analog trigger.

The counter will start counting immediately.

Parameters

trigger The reference to the existing AnalogTrigger object.

◆ Counter() [6/8]

frc::Counter::Counter	(	EncodingType	encodingType,
		DigitalSource *	upSource,
		DigitalSource *	downSource,
		bool	inverted
	)

Create an instance of a Counter object.

Creates a full up-down counter given two Digital Sources.

Parameters

encodingType	The quadrature decoding mode (1x or 2x)
upSource	The pointer to the DigitalSource to set as the up source
downSource	The pointer to the DigitalSource to set as the down source
inverted	True to invert the output (reverse the direction)

◆ Counter() [7/8]

frc::Counter::Counter	(	EncodingType	encodingType,
		std::shared_ptr< DigitalSource >	upSource,
		std::shared_ptr< DigitalSource >	downSource,
		bool	inverted
	)

Create an instance of a Counter object.

Creates a full up-down counter given two Digital Sources.

Parameters

encodingType	The quadrature decoding mode (1x or 2x)
upSource	The pointer to the DigitalSource to set as the up source
downSource	The pointer to the DigitalSource to set as the down source
inverted	True to invert the output (reverse the direction)

◆ ~Counter()

frc::Counter::~Counter ( )

override

◆ Counter() [8/8]

frc::Counter::Counter ( Counter && )

default

Member Function Documentation

◆ ClearDownSource()

void frc::Counter::ClearDownSource ( )

Disable the down counting source to the counter.

◆ ClearUpSource()

void frc::Counter::ClearUpSource ( )

Disable the up counting source to the counter.

◆ Get()

int frc::Counter::Get ( ) const

overridevirtual

Read the current counter value.

Read the value at this instant. It may still be running, so it reflects the current value. Next time it is read, it might have a different value.

Implements frc::CounterBase.

◆ GetDirection()

bool frc::Counter::GetDirection ( ) const

overridevirtual

The last direction the counter value changed.

Returns: The last direction the counter value changed.

Implements frc::CounterBase.

◆ GetDistance()

double frc::Counter::GetDistance ( ) const

Read the current scaled counter value.

Read the value at this instant, scaled by the distance per pulse (defaults to 1).

Returns: The distance since the last reset

◆ GetFPGAIndex()

int frc::Counter::GetFPGAIndex ( ) const

◆ GetPeriod()

units::second_t frc::Counter::GetPeriod ( ) const

overridevirtual

Get the Period of the most recent count.

Returns the time interval of the most recent count. This can be used for velocity calculations to determine shaft speed.

Returns: The period between the last two pulses in units of seconds.

Implements frc::CounterBase.

◆ GetRate()

double frc::Counter::GetRate ( ) const

Get the current rate of the Counter.

Read the current rate of the counter accounting for the distance per pulse value. The default value for distance per pulse (1) yields units of pulses per second.

Returns: The rate in units/sec

◆ GetSamplesToAverage()

int frc::Counter::GetSamplesToAverage ( ) const

Get the Samples to Average which specifies the number of samples of the timer to average when calculating the period.

Perform averaging to account for mechanical imperfections or as oversampling to increase resolution.

Returns: The number of samples being averaged (from 1 to 127)

◆ GetStopped()

bool frc::Counter::GetStopped ( ) const

overridevirtual

Determine if the clock is stopped.

Determine if the clocked input is stopped based on the MaxPeriod value set using the SetMaxPeriod method. If the clock exceeds the MaxPeriod, then the device (and counter) are assumed to be stopped and it returns true.

Returns: Returns true if the most recent counter period exceeds the MaxPeriod value set by SetMaxPeriod.

Implements frc::CounterBase.

◆ InitSendable()

void frc::Counter::InitSendable ( wpi::SendableBuilder & builder )

overridevirtual

Initializes this Sendable object.

Parameters

builder sendable builder

Implements wpi::Sendable.

◆ operator=()

Counter & frc::Counter::operator= ( Counter && )

default

◆ Reset()

void frc::Counter::Reset ( )

overridevirtual

Reset the Counter to zero.

Set the counter value to zero. This doesn't effect the running state of the counter, just sets the current value to zero.

Implements frc::CounterBase.

◆ SetDistancePerPulse()

void frc::Counter::SetDistancePerPulse ( double distancePerPulse )

Set the distance per pulse for this counter.

This sets the multiplier used to determine the distance driven based on the count value from the encoder. Set this value based on the Pulses per Revolution and factor in any gearing reductions. This distance can be in any units you like, linear or angular.

Parameters

distancePerPulse The scale factor that will be used to convert pulses to useful units.

◆ SetDownSource() [1/6]

void frc::Counter::SetDownSource	(	AnalogTrigger *	analogTrigger,
		AnalogTriggerType	triggerType
	)

Set the down counting source to be an analog trigger.

Parameters

analogTrigger	The analog trigger object that is used for the Down Source
triggerType	The analog trigger output that will trigger the counter.

◆ SetDownSource() [2/6]

void frc::Counter::SetDownSource ( DigitalSource & source )

Set the source object that causes the counter to count down.

Set the down counting DigitalSource.

Parameters

source Reference to the DigitalSource object to set as the down source

◆ SetDownSource() [3/6]

void frc::Counter::SetDownSource ( DigitalSource * source )

Set the source object that causes the counter to count down.

Set the down counting DigitalSource.

Parameters

source Pointer to the DigitalSource object to set as the down source

◆ SetDownSource() [4/6]

void frc::Counter::SetDownSource ( int channel )

Set the down counting source to be a digital input channel.

Parameters

channel The DIO channel to use as the up source. 0-9 are on-board, 10-25 are on the MXP

◆ SetDownSource() [5/6]

void frc::Counter::SetDownSource	(	std::shared_ptr< AnalogTrigger >	analogTrigger,
		AnalogTriggerType	triggerType
	)

Set the down counting source to be an analog trigger.

Parameters

analogTrigger	The analog trigger object that is used for the Down Source
triggerType	The analog trigger output that will trigger the counter.

◆ SetDownSource() [6/6]

void frc::Counter::SetDownSource ( std::shared_ptr< DigitalSource > source )

◆ SetDownSourceEdge()

void frc::Counter::SetDownSourceEdge	(	bool	risingEdge,
		bool	fallingEdge
	)

Set the edge sensitivity on a down counting source.

Set the down source to either detect rising edges or falling edges.

Parameters

risingEdge	True to trigger on rising edges
fallingEdge	True to trigger on falling edges

◆ SetExternalDirectionMode()

void frc::Counter::SetExternalDirectionMode ( )

Set external direction mode on this counter.

Counts are sourced on the Up counter input. The Down counter input represents the direction to count.

◆ SetMaxPeriod()

void frc::Counter::SetMaxPeriod ( units::second_t maxPeriod )

finalvirtual

Set the maximum period where the device is still considered "moving".

Sets the maximum period where the device is considered moving. This value is used to determine the "stopped" state of the counter using the GetStopped method.

Parameters

maxPeriod The maximum period where the counted device is considered moving in seconds.

Implements frc::CounterBase.

◆ SetPulseLengthMode()

void frc::Counter::SetPulseLengthMode ( double threshold )

Configure the counter to count in up or down based on the length of the input pulse.

This mode is most useful for direction sensitive gear tooth sensors.

Parameters

threshold The pulse length beyond which the counter counts the opposite direction. Units are seconds.

◆ SetReverseDirection()

void frc::Counter::SetReverseDirection ( bool reverseDirection )

Set the Counter to return reversed sensing on the direction.

This allows counters to change the direction they are counting in the case of 1X and 2X quadrature encoding only. Any other counter mode isn't supported.

Parameters

reverseDirection true if the value counted should be negated.

◆ SetSamplesToAverage()

void frc::Counter::SetSamplesToAverage ( int samplesToAverage )

Set the Samples to Average which specifies the number of samples of the timer to average when calculating the period.

Perform averaging to account for mechanical imperfections or as oversampling to increase resolution.

Parameters

samplesToAverage The number of samples to average from 1 to 127.

◆ SetSemiPeriodMode()

void frc::Counter::SetSemiPeriodMode ( bool highSemiPeriod )

Set Semi-period mode on this counter.

Counts up on both rising and falling edges.

◆ SetUpdateWhenEmpty()

void frc::Counter::SetUpdateWhenEmpty ( bool enabled )

Select whether you want to continue updating the event timer output when there are no samples captured.

The output of the event timer has a buffer of periods that are averaged and posted to a register on the FPGA. When the timer detects that the event source has stopped (based on the MaxPeriod) the buffer of samples to be averaged is emptied. If you enable the update when empty, you will be notified of the stopped source and the event time will report 0 samples. If you disable update when empty, the most recent average will remain on the output until a new sample is acquired. You will never see 0 samples output (except when there have been no events since an FPGA reset) and you will likely not see the stopped bit become true (since it is updated at the end of an average and there are no samples to average).

Parameters

enabled True to enable update when empty

◆ SetUpDownCounterMode()

void frc::Counter::SetUpDownCounterMode ( )

Set standard up / down counting mode on this counter.

Up and down counts are sourced independently from two inputs.

◆ SetUpSource() [1/6]

void frc::Counter::SetUpSource	(	AnalogTrigger *	analogTrigger,
		AnalogTriggerType	triggerType
	)

Set the up counting source to be an analog trigger.

Parameters

analogTrigger	The analog trigger object that is used for the Up Source
triggerType	The analog trigger output that will trigger the counter.

◆ SetUpSource() [2/6]

void frc::Counter::SetUpSource ( DigitalSource & source )

Set the source object that causes the counter to count up.

Set the up counting DigitalSource.

Parameters

source Reference to the DigitalSource object to set as the up source

◆ SetUpSource() [3/6]

void frc::Counter::SetUpSource ( DigitalSource * source )

◆ SetUpSource() [4/6]

void frc::Counter::SetUpSource ( int channel )

Set the upsource for the counter as a digital input channel.

Parameters

channel The DIO channel to use as the up source. 0-9 are on-board, 10-25 are on the MXP

◆ SetUpSource() [5/6]

void frc::Counter::SetUpSource	(	std::shared_ptr< AnalogTrigger >	analogTrigger,
		AnalogTriggerType	triggerType
	)

Set the up counting source to be an analog trigger.

Parameters

analogTrigger	The analog trigger object that is used for the Up Source
triggerType	The analog trigger output that will trigger the counter.

◆ SetUpSource() [6/6]

void frc::Counter::SetUpSource ( std::shared_ptr< DigitalSource > source )

Set the source object that causes the counter to count up.

Set the up counting DigitalSource.

Parameters

source Pointer to the DigitalSource object to set as the up source

◆ SetUpSourceEdge()

void frc::Counter::SetUpSourceEdge	(	bool	risingEdge,
		bool	fallingEdge
	)

Set the edge sensitivity on an up counting source.

Set the up source to either detect rising edges or falling edges or both.

Parameters

risingEdge	True to trigger on rising edges
fallingEdge	True to trigger on falling edges

Friends And Related Function Documentation

◆ DigitalGlitchFilter

friend class DigitalGlitchFilter

friend

◆ DMA

friend class DMA

friend

◆ DMASample

friend class DMASample

friend

Member Data Documentation

◆ m_counter

hal::Handle<HAL_CounterHandle> frc::Counter::m_counter

protected

The FPGA counter object.

◆ m_downSource

std::shared_ptr<DigitalSource> frc::Counter::m_downSource

protected

Makes the counter count down.

◆ m_upSource

std::shared_ptr<DigitalSource> frc::Counter::m_upSource

protected

Makes the counter count up.

The documentation for this class was generated from the following file:

frc/Counter.h

Public Types

Public Member Functions

Protected Attributes

Friends

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ Mode

Constructor & Destructor Documentation

◆ Counter() [1/8]

◆ Counter() [2/8]

◆ Counter() [3/8]

◆ Counter() [4/8]

◆ Counter() [5/8]

◆ Counter() [6/8]

◆ Counter() [7/8]

◆ ~Counter()

◆ Counter() [8/8]

Member Function Documentation

◆ ClearDownSource()

◆ ClearUpSource()

◆ Get()

◆ GetDirection()

◆ GetDistance()

◆ GetFPGAIndex()

◆ GetPeriod()

◆ GetRate()

◆ GetSamplesToAverage()

◆ GetStopped()

◆ InitSendable()

◆ operator=()

◆ Reset()

◆ SetDistancePerPulse()

◆ SetDownSource() [1/6]

◆ SetDownSource() [2/6]

◆ SetDownSource() [3/6]

◆ SetDownSource() [4/6]

◆ SetDownSource() [5/6]

◆ SetDownSource() [6/6]

◆ SetDownSourceEdge()

◆ SetExternalDirectionMode()

◆ SetMaxPeriod()

◆ SetPulseLengthMode()

◆ SetReverseDirection()

◆ SetSamplesToAverage()

◆ SetSemiPeriodMode()

◆ SetUpdateWhenEmpty()

◆ SetUpDownCounterMode()

◆ SetUpSource() [1/6]

◆ SetUpSource() [2/6]

◆ SetUpSource() [3/6]

◆ SetUpSource() [4/6]

◆ SetUpSource() [5/6]

◆ SetUpSource() [6/6]

◆ SetUpSourceEdge()

Friends And Related Function Documentation

◆ DigitalGlitchFilter

◆ DMA

◆ DMASample

Member Data Documentation

◆ m_counter

◆ m_downSource

◆ m_upSource