frc::TimeOfFlight Class Reference

#include <TimeOfFlight.h>

Inheritance diagram for frc::TimeOfFlight:

Public Types
enum	RangingMode { kShort = 0 , kMedium = 1 , kLong = 2 }
enum	Status {   kValid = 0 , kSigmaHigh = 1 , kReturnSignalLow = 2 , kReturnPhaseBad = 4 ,   kHardwareFailure = 5 , kWrappedTarget = 7 , kInternalError = 8 , kInvalid = 14 }

Public Member Functions
	TimeOfFlight (uint8_t sensorID)
virtual	~TimeOfFlight ()
	TimeOfFlight (const TimeOfFlight &)=delete
TimeOfFlight &	operator= (const TimeOfFlight &)=delete
	TimeOfFlight (TimeOfFlight &&)=default
TimeOfFlight &	operator= (TimeOfFlight &&)=default
void	IdentifySensor ()
uint32_t	GetFirmwareVersion () const
uint32_t	GetSerialNumber () const
bool	IsRangeValid () const
double	GetRange () const
double	GetRangeSigma () const
double	GetAmbientLightLevel () const
Status	GetStatus () const
void	SetRangingMode (RangingMode mode, double sampleTime)
void	SetRangeOfInterest (uint8_t topLeftX, uint8_t topLeftY, uint8_t bottomRightX, uint8_t bottomRightY)
void	InitSendable (wpi::SendableBuilder &builder) override

Member Enumeration Documentation

RangingMode

enum frc::TimeOfFlight::RangingMode

Enumerator
kShort
kMedium
kLong

Status

enum frc::TimeOfFlight::Status

Enumerator
kValid	Measured distance is valid
kSigmaHigh	Sigma estimator check is above internally defined threshold. The repeatability or standard deviation of the measurement is bad due to a decreasing signal noise ratio. Increasing the timing budget can improve the standard deviation.
kReturnSignalLow	Return signal value is below the internal defined threshold. The return signal is too week to return a good answer. The target may be too far, not reflective enough, or too small. Increasing the timing buget might help, but there may simply be no target available.
kReturnPhaseBad	Return signal phase is out of bounds. This means that the sensor is ranging in a "nonappropriated" zone and the measured result may be inconsistent. This status is considered as a warning but, in general, it happens when a target is at the maximum distance possible from the sensor.
kHardwareFailure	Hardware failure
kWrappedTarget	Wrapped target, non-matching phases. This situation may occur when the target is very reflective and the distance to the target/sensor is longer than the physical limited distance measurable by the sensor. For example, approximately 5m when the senor is in Long distance mode and approximately 1.3 m when the sensor is in Short distance mode.
kInternalError	Internal algorithm underflow or overflow
kInvalid	The measured distance is invalid

Constructor & Destructor Documentation

TimeOfFlight() [1/3]

TimeOfFlight::TimeOfFlight ( uint8_t  sensorID )

explicit

Create an instance of the CAN Time Of Flight sensor.

This is designed to support the Playing With Fusion (PWF) SEN-36005 time of flight sensor

Parameters

sensorID

The 6-bit identifier used to select a particular sensor on the CAN bus. This identifier may be set through the PWF Device configuration page on the roboRIO.

~TimeOfFlight()

TimeOfFlight::~TimeOfFlight ( )

virtual

TimeOfFlight() [2/3]

frc::TimeOfFlight::TimeOfFlight ( const TimeOfFlight &  )

delete

TimeOfFlight() [3/3]

frc::TimeOfFlight::TimeOfFlight ( TimeOfFlight &&  )

default

Member Function Documentation

GetAmbientLightLevel()

double TimeOfFlight::GetAmbientLightLevel

(

)

const

Get ambient lighting level in mega counts per second.

Returns

Ambient lighting level in mega counts per second.

GetFirmwareVersion()

uint32_t TimeOfFlight::GetFirmwareVersion

(

)

const

Determine the sensor firmware version

Returns

The sensor firmware version

GetRange()

double TimeOfFlight::GetRange

(

)

const

Get the distance between the sensor and the target

Returns

Distance to target in millimeters

GetRangeSigma()

double TimeOfFlight::GetRangeSigma

(

)

const

Get the standard deviation of the distance measurment in millimeters

Returns

Standard deviation of distance measurment in millimeters

GetSerialNumber()

uint32_t TimeOfFlight::GetSerialNumber

(

)

const

Determine the sensor hardware serial number

Returns

The sensor hardware serial number

GetStatus()

TimeOfFlight::Status TimeOfFlight::GetStatus

(

)

const

Get status of the last distance measurement.

Returns

Status of last measurement. See VL53L1X datasheet for more details

IdentifySensor()

void TimeOfFlight::IdentifySensor

(

)

Flash the time of flight sensor LED red and green to idicate the sensor asscioated with this instance of software

InitSendable()

void TimeOfFlight::InitSendable ( wpi::SendableBuilder &  builder )

override

IsRangeValid()

bool TimeOfFlight::IsRangeValid

(

)

const

Determine if the last measurment was valid

Returns

TRUE if the Time Of Flight Sensor sucessfully measured distance to an object

operator=() [1/2]

TimeOfFlight & frc::TimeOfFlight::operator= ( const TimeOfFlight &  )

delete

operator=() [2/2]

TimeOfFlight & frc::TimeOfFlight::operator= ( TimeOfFlight &&  )

default

SetRangeOfInterest()

void TimeOfFlight::SetRangeOfInterest	(	uint8_t	topLeftX,
		uint8_t	topLeftY,
		uint8_t	bottomRightX,
		uint8_t	bottomRightY
	)

Specify the region of the imaging sensor used for range measurement.

The region of interest refers to the pixels within the time of flight imaging sensor that are used to detect reflected laser light form the target. The sensor contains a 16x16 pixel grid. By default, all 256 pixels are used which results in a roughly 27 degree field of view.

The Field of view refers to a cone which grows from the time of flight sensor outward. By reducing the size of the region of interest (by using a smaller area of pixels) it is possible to reduce the field of view. This can be helpfull when measuring objects far away. The smaller the field of view, the smaller the area where the sensor can detect targets.

Reducing the region of interest will reduce the sensitivity of the sensor. It may be necessary to increase the reflectivity of the target or to increase the sample time to compensate.

The range of interest rows and columns must be greater or equal to zero and less than or equal to fifteen. The top left corner row/column must be smaller than the bottom right column/row. The region of interest must be at least four coulmns wide and four rows tall. For example, to specify a 4x4 region at the center of the image sensor use:

TimeOfFlight_SetRangeOfInterest(pHandle, 8, 8, 12, 12);

Parameters

topLeftX	Column of the top left corner of the region of interest.
topLeftY	Row of the top left corner of the region of interest.
bottomRightX	Column of the bottom right corner of the region of interest.
bottomRightY	Row of the bottom right corner of the region of interest.

SetRangingMode()

void TimeOfFlight::SetRangingMode	(	RangingMode	mode,
		double	sampleTime
	)

Configure the ranging mode as well as the sample rate of the time of flight sensor

The ranging mode specifies the trade off between maximum measure distance verses reliablity in bright situations. Short mode (default) works the best in bright lighting conditions, but can only measure 1.3 meters. Long mode can measure up to 4 meters in the dark, but may only be able to measure shorter distances depending on the lighting conditions. See the Vl53L1x datasheet for more information

The sample time specifies the how frequently the time of flight sensor attempts to measure the distance to a target. The sample time must be between 24 and 1000 milliseconds.

Parameters

mode	The desired sensor ranging mode (short, medium, long)
sampleTime	The desired sample time in milliseconds

---

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

• src/main/native/include/TimeOfFlight.h
• src/main/native/cpp/TimeOfFlight.cpp