edu.wpi.first.wpilibj

Class Ultrasonic

java.lang.Object

edu.wpi.first.wpilibj.SensorBase

edu.wpi.first.wpilibj.Ultrasonic

All Implemented Interfaces:

LiveWindowSendable, PIDSource, Sendable

public class Ultrasonic
extends SensorBase
implements PIDSource, LiveWindowSendable

Ultrasonic rangefinder class. The Ultrasonic rangefinder measures absolute distance based on the round-trip time of a ping generated by the controller. These sensors use two transducers, a speaker and a microphone both tuned to the ultrasonic range. A common ultrasonic sensor, the Daventech SRF04 requires a short pulse to be generated on a digital channel. This causes the chirp to be emmitted. A second line becomes high as the ping is transmitted and goes low when the echo is received. The time that the line is high determines the round trip distance (time of flight).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Ultrasonic.Unit The units to return when PIDGet is called.

Field Summary

Fields

Modifier and Type	Field and Description
protected PIDSourceType	m_pidSource

Fields inherited from class edu.wpi.first.wpilibj.SensorBase

kAnalogInputChannels, kAnalogOutputChannels, kDigitalChannels, kPCMModules, kPDPChannels, kPDPModules, kPwmChannels, kRelayChannels, kSolenoidChannels, kSystemClockTicksPerMicrosecond

Constructor Summary

Constructors

Constructor and Description
Ultrasonic(DigitalOutput pingChannel, DigitalInput echoChannel) Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo channel and a DigitalOutput for the ping channel.
Ultrasonic(DigitalOutput pingChannel, DigitalInput echoChannel, Ultrasonic.Unit units) Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo channel and a DigitalOutput for the ping channel.
Ultrasonic(int pingChannel, int echoChannel) Create an instance of the Ultrasonic Sensor.
Ultrasonic(int pingChannel, int echoChannel, Ultrasonic.Unit units) Create an instance of the Ultrasonic Sensor.

Method Summary

Modifier and Type	Method and Description
void	free() Destructor for the ultrasonic sensor.
Ultrasonic.Unit	getDistanceUnits() Get the current DistanceUnit that is used for the PIDSource base object.
PIDSourceType	getPIDSourceType() Get which parameter of the device you are using as a process control variable.
double	getRangeInches() Get the range in inches from the ultrasonic sensor.
double	getRangeMM() Get the range in millimeters from the ultrasonic sensor.
java.lang.String	getSmartDashboardType() Live Window code, only does anything if live window is activated.
ITable	getTable() The table that is associated with this Sendable.
void	initTable(ITable subtable) Initializes a table for this Sendable object.
boolean	isEnabled() Is the ultrasonic enabled.
boolean	isRangeValid() Check if there is a valid range measurement.
double	pidGet() Get the range in the current DistanceUnit for the PIDSource base object.
void	ping() Single ping to ultrasonic sensor.
void	setAutomaticMode(boolean enabling) Turn Automatic mode on/off.
void	setDistanceUnits(Ultrasonic.Unit units) Set the current DistanceUnit that should be used for the PIDSource base object.
void	setEnabled(boolean enable) Set if the ultrasonic is enabled.
void	setPIDSourceType(PIDSourceType pidSource) Set which parameter of the device you are using as a process control variable.
void	startLiveWindowMode() Start having this sendable object automatically respond to value changes reflect the value on the table.
void	stopLiveWindowMode() Stop having this sendable object automatically respond to value changes.
void	updateTable() Update the table for this sendable object with the latest values.

Methods inherited from class edu.wpi.first.wpilibj.SensorBase

checkAnalogInputChannel, checkAnalogOutputChannel, checkDigitalChannel, checkPDPChannel, checkPDPModule, checkPWMChannel, checkRelayChannel, checkSolenoidChannel, checkSolenoidModule, getDefaultSolenoidModule, setDefaultSolenoidModule

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_pidSource

protected PIDSourceType m_pidSource

Constructor Detail

Ultrasonic

public Ultrasonic(int pingChannel,
                  int echoChannel,
                  Ultrasonic.Unit units)

Create an instance of the Ultrasonic Sensor. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors.

Parameters:

pingChannel - The digital output channel that sends the pulse to initiate the sensor sending the ping.

echoChannel - The digital input channel that receives the echo. The length of time that the echo is high represents the round trip time of the ping, and the distance.

units - The units returned in either kInches or kMilliMeters

Ultrasonic

public Ultrasonic(int pingChannel,
                  int echoChannel)

Create an instance of the Ultrasonic Sensor. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors. Default unit is inches.

Parameters:

pingChannel - The digital output channel that sends the pulse to initiate the sensor sending the ping.

echoChannel - The digital input channel that receives the echo. The length of time that the echo is high represents the round trip time of the ping, and the distance.

Ultrasonic

public Ultrasonic(DigitalOutput pingChannel,
                  DigitalInput echoChannel,
                  Ultrasonic.Unit units)

Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo channel and a DigitalOutput for the ping channel.

Parameters:

pingChannel - The digital output object that starts the sensor doing a ping. Requires a 10uS pulse to start.

echoChannel - The digital input object that times the return pulse to determine the range.

units - The units returned in either kInches or kMilliMeters

Ultrasonic

public Ultrasonic(DigitalOutput pingChannel,
                  DigitalInput echoChannel)

Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo channel and a DigitalOutput for the ping channel. Default unit is inches.

Parameters:

pingChannel - The digital output object that starts the sensor doing a ping. Requires a 10uS pulse to start.

echoChannel - The digital input object that times the return pulse to determine the range.

Method Detail

free

public void free()

Destructor for the ultrasonic sensor. Delete the instance of the ultrasonic sensor by freeing the allocated digital channels. If the system was in automatic mode (round robin), then it is stopped, then started again after this sensor is removed (provided this wasn't the last sensor).

Overrides:

free in class SensorBase

setAutomaticMode

public void setAutomaticMode(boolean enabling)

Turn Automatic mode on/off. When in Automatic mode, all sensors will fire in round robin, waiting a set time between each sensor.

Parameters:

enabling - Set to true if round robin scheduling should start for all the ultrasonic sensors. This scheduling method assures that the sensors are non-interfering because no two sensors fire at the same time. If another scheduling algorithm is preffered, it can be implemented by pinging the sensors manually and waiting for the results to come back.

ping

public void ping()

Single ping to ultrasonic sensor. Send out a single ping to the ultrasonic sensor. This only works if automatic (round robin) mode is disabled. A single ping is sent out, and the counter should count the semi-period when it comes in. The counter is reset to make the current value invalid.

isRangeValid

public boolean isRangeValid()

Check if there is a valid range measurement. The ranges are accumulated in a counter that will increment on each edge of the echo (return) signal. If the count is not at least 2, then the range has not yet been measured, and is invalid.

Returns:

true if the range is valid

getRangeInches

public double getRangeInches()

Get the range in inches from the ultrasonic sensor. If there is no valid value yet, i.e. at least one measurement hasn't completed, then return 0.

Returns:

double Range in inches of the target returned from the ultrasonic sensor.

getRangeMM

public double getRangeMM()

Get the range in millimeters from the ultrasonic sensor. If there is no valid value yet, i.e. at least one measurement hasn't completed, then return 0.

Returns:

double Range in millimeters of the target returned by the ultrasonic sensor.

setPIDSourceType

public void setPIDSourceType(PIDSourceType pidSource)

Description copied from interface: PIDSource

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

Specified by:

setPIDSourceType in interface PIDSource

Parameters:

pidSource - An enum to select the parameter.

getPIDSourceType

public PIDSourceType getPIDSourceType()

Description copied from interface: PIDSource

Get which parameter of the device you are using as a process control variable.

Specified by:

getPIDSourceType in interface PIDSource

Returns:

the currently selected PID source parameter

pidGet

public double pidGet()

Get the range in the current DistanceUnit for the PIDSource base object.

Specified by:

pidGet in interface PIDSource

Returns:

The range in DistanceUnit

setDistanceUnits

public void setDistanceUnits(Ultrasonic.Unit units)

Set the current DistanceUnit that should be used for the PIDSource base object.

Parameters:

units - The DistanceUnit that should be used.

getDistanceUnits

public Ultrasonic.Unit getDistanceUnits()

Get the current DistanceUnit that is used for the PIDSource base object.

Returns:

The type of DistanceUnit that is being used.

isEnabled

public boolean isEnabled()

Is the ultrasonic enabled.

Returns:

true if the ultrasonic is enabled

setEnabled

public void setEnabled(boolean enable)

Set if the ultrasonic is enabled.

Parameters:

enable - set to true to enable the ultrasonic

getSmartDashboardType

public java.lang.String getSmartDashboardType()

Live Window code, only does anything if live window is activated.

Specified by:

getSmartDashboardType in interface Sendable

Returns:

The type of this Sendable.

initTable

public void initTable(ITable subtable)

Description copied from interface: Sendable

Initializes a table for this Sendable object.

Specified by:

initTable in interface Sendable

Parameters:

subtable - The table to put the values in.

getTable

public ITable getTable()

Description copied from interface: Sendable

The table that is associated with this Sendable.

Specified by:

getTable in interface Sendable

Returns:

the table that is currently associated with the Sendable.

updateTable

public void updateTable()

Description copied from interface: LiveWindowSendable

Update the table for this sendable object with the latest values.

Specified by:

updateTable in interface LiveWindowSendable

startLiveWindowMode

public void startLiveWindowMode()

Description copied from interface: LiveWindowSendable

Start having this sendable object automatically respond to value changes reflect the value on the table.

Specified by:

startLiveWindowMode in interface LiveWindowSendable

stopLiveWindowMode

public void stopLiveWindowMode()

Description copied from interface: LiveWindowSendable

Stop having this sendable object automatically respond to value changes.

Specified by:

stopLiveWindowMode in interface LiveWindowSendable