Encoder Class Reference

#include <Encoder.h>

Inheritance diagram for Encoder:

Public Member Functions
	Encoder (uint32_t aChannel, uint32_t bChannel, bool reverseDirection=false, EncodingType encodingType=k4X)
	Encoder (uint8_t aModuleNumber, uint32_t aChannel, uint8_t bModuleNumber, uint32_t _bChannel, bool reverseDirection=false, EncodingType encodingType=k4X)
	Encoder (DigitalSource *aSource, DigitalSource *bSource, bool reverseDirection=false, EncodingType encodingType=k4X)
	Encoder (DigitalSource &aSource, DigitalSource &bSource, bool reverseDirection=false, EncodingType encodingType=k4X)
virtual	~Encoder ()
void	Start ()
int32_t	Get ()
int32_t	GetRaw ()
void	Reset ()
void	Stop ()
double	GetPeriod ()
void	SetMaxPeriod (double maxPeriod)
bool	GetStopped ()
bool	GetDirection ()
double	GetDistance ()
double	GetRate ()
void	SetMinRate (double minRate)
void	SetDistancePerPulse (double distancePerPulse)
void	SetReverseDirection (bool reverseDirection)
void	SetSamplesToAverage (int samplesToAverage)
int	GetSamplesToAverage ()
void	SetPIDSourceParameter (PIDSourceParameter pidSource)
double	PIDGet ()
void	UpdateTable ()
void	StartLiveWindowMode ()
void	StopLiveWindowMode ()
std::string	GetSmartDashboardType ()
void	InitTable (ITable *subTable)
ITable *	GetTable ()
Public Member Functions inherited from SensorBase
	SensorBase ()
virtual	~SensorBase ()
Public Member Functions inherited from ErrorBase
virtual Error &	GetError ()
	Retrieve the current error. Get the current error information associated with this sensor.
virtual const Error &	GetError () const
virtual void	SetErrnoError (const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber) const
	Set error information associated with a C library call that set an error to the "errno" global variable. More...
virtual void	SetImaqError (int success, const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber) const
	Set the current error information associated from the nivision Imaq API. More...
virtual void	SetError (Error::Code code, const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber) const
	Set the current error information associated with this sensor. More...
virtual void	SetWPIError (const char *errorMessage, const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber) const
	Set the current error information associated with this sensor. More...
virtual void	CloneError (ErrorBase *rhs) const
virtual void	ClearError () const
	Clear the current error information associated with this sensor.
virtual bool	StatusIsFatal () const
	Check if the current error code represents a fatal error. More...

Additional Inherited Members
Public Types inherited from CounterBase
enum	EncodingType { k1X, k2X, k4X }
Public Types inherited from PIDSource
enum	PIDSourceParameter { kDistance, kRate, kAngle }
Static Public Member Functions inherited from SensorBase
static void	DeleteSingletons ()
static uint32_t	GetDefaultAnalogModule ()
static uint32_t	GetDefaultDigitalModule ()
static uint32_t	GetDefaultSolenoidModule ()
static bool	CheckAnalogModule (uint8_t moduleNumber)
static bool	CheckDigitalModule (uint8_t moduleNumber)
static bool	CheckPWMModule (uint8_t moduleNumber)
static bool	CheckRelayModule (uint8_t moduleNumber)
static bool	CheckSolenoidModule (uint8_t moduleNumber)
static bool	CheckDigitalChannel (uint32_t channel)
static bool	CheckRelayChannel (uint32_t channel)
static bool	CheckPWMChannel (uint32_t channel)
static bool	CheckAnalogChannel (uint32_t channel)
static bool	CheckSolenoidChannel (uint32_t channel)
Static Public Member Functions inherited from ErrorBase
static void	SetGlobalError (Error::Code code, const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber)
static void	SetGlobalWPIError (const char *errorMessage, const char *contextMessage, const char *filename, const char *function, uint32_t lineNumber)
static Error &	GetGlobalError ()
Static Public Attributes inherited from SensorBase
static const uint32_t	kSystemClockTicksPerMicrosecond = 40
static const uint32_t	kDigitalChannels = 14
static const uint32_t	kAnalogChannels = 8
static const uint32_t	kAnalogModules = 2
static const uint32_t	kDigitalModules = 2
static const uint32_t	kSolenoidChannels = 8
static const uint32_t	kSolenoidModules = 2
static const uint32_t	kPwmChannels = 10
static const uint32_t	kRelayChannels = 8
static const uint32_t	kChassisSlots = 8
Protected Member Functions inherited from SensorBase
void	AddToSingletonList ()
Protected Member Functions inherited from ErrorBase
	ErrorBase ()
	Initialize the instance status to 0 for now.
Protected Attributes inherited from ErrorBase
Error	m_error
Static Protected Attributes inherited from ErrorBase
static SEM_ID	_globalErrorMutex = semMCreate(SEM_Q_PRIORITY | SEM_DELETE_SAFE | SEM_INVERSION_SAFE)
static Error	_globalError

Detailed Description

Class to read quad encoders. Quadrature encoders are devices that count shaft rotation and can sense direction. The output of the QuadEncoder class is an integer that can count either up or down, and can go negative for reverse direction counting. When creating QuadEncoders, a direction is supplied that changes the sense of the output to make code more readable if the encoder is mounted such that forward movement generates negative values. Quadrature encoders have two digital outputs, an A Channel and a B Channel that are out of phase with each other to allow the FPGA to do direction sensing.

Constructor & Destructor Documentation

Encoder::~Encoder ( )

virtual

Free the resources for an Encoder. Frees the FPGA resources associated with an Encoder.

Member Function Documentation

int32_t Encoder::Get ( )

virtual

Gets the current count. Returns the current count on the Encoder. This method compensates for the decoding type.

Returns

Current count from the Encoder adjusted for the 1x, 2x, or 4x scale factor.

Implements CounterBase.

bool Encoder::GetDirection ( )

virtual

The last direction the encoder value changed.

Returns

The last direction the encoder value changed.

Implements CounterBase.

double Encoder::GetDistance

(

)

Get the distance the robot has driven since the last reset.

Returns

The distance driven since the last reset as scaled by the value from SetDistancePerPulse().

double Encoder::GetPeriod ( )

virtual

Returns the period of the most recent pulse. Returns the period of the most recent Encoder pulse in seconds. This method compenstates for the decoding type.

Deprecated:

Use GetRate() in favor of this method. This returns unscaled periods and GetRate() scales using value from SetDistancePerPulse().

Returns

Period in seconds of the most recent pulse.

Implements CounterBase.

double Encoder::GetRate

(

)

Get the current rate of the encoder. Units are distance per second as scaled by the value from SetDistancePerPulse().

Returns

The current rate of the encoder.

int32_t Encoder::GetRaw

(

)

Gets the raw value from the encoder. The raw value is the actual count unscaled by the 1x, 2x, or 4x scale factor.

Returns

Current raw count from the encoder

int Encoder::GetSamplesToAverage

(

)

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

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

bool Encoder::GetStopped ( )

virtual

Determine if the encoder is stopped. Using the MaxPeriod value, a boolean is returned that is true if the encoder is considered stopped and false if it is still moving. A stopped encoder is one where the most recent pulse width exceeds the MaxPeriod.

Returns

True if the encoder is considered stopped.

Implements CounterBase.

double Encoder::PIDGet ( )

virtual

Implement the PIDSource interface.

Returns

The current value of the selected source parameter.

Implements PIDSource.

void Encoder::Reset ( )

virtual

Reset the Encoder distance to zero. Resets the current count to zero on the encoder.

Implements CounterBase.

void Encoder::SetDistancePerPulse

(

double

distancePerPulse

)

Set the distance per pulse for this encoder. This sets the multiplier used to determine the distance driven based on the count value from the encoder. Do not include the decoding type in this scale. The library already compensates for the decoding type. Set this value based on the encoder's rated Pulses per Revolution and factor in gearing reductions following the encoder shaft. 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.

void Encoder::SetMaxPeriod ( double  maxPeriod )

virtual

Sets the maximum period for stopped detection. Sets the value that represents the maximum period of the Encoder before it will assume that the attached device is stopped. This timeout allows users to determine if the wheels or other shaft has stopped rotating. This method compensates for the decoding type.

Deprecated:

Use SetMinRate() in favor of this method. This takes unscaled periods and SetMinRate() scales using value from SetDistancePerPulse().

Parameters

maxPeriod

The maximum time between rising and falling edges before the FPGA will report the device stopped. This is expressed in seconds.

Implements CounterBase.

void Encoder::SetMinRate

(

double

minRate

)

Set the minimum rate of the device before the hardware reports it stopped.

Parameters

minRate

The minimum rate. The units are in distance per second as scaled by the value from SetDistancePerPulse().

void Encoder::SetPIDSourceParameter

(

PIDSourceParameter

pidSource

)

Set which parameter of the encoder you are using as a process control variable.

Parameters

pidSource

An enum to select the parameter.

void Encoder::SetReverseDirection

(

bool

reverseDirection

)

Set the direction sensing for this encoder. This sets the direction sensing on the encoder so that it could count in the correct software direction regardless of the mounting.

Parameters

reverseDirection

true if the encoder direction should be reversed

void Encoder::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.

void Encoder::Start ( )

virtual

Start the Encoder. Starts counting pulses on the Encoder device.

Implements CounterBase.

void Encoder::Stop ( )

virtual

Stops counting pulses on the Encoder device. The value is not changed.

Implements CounterBase.

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

• Encoder.h
• Encoder.cpp