edu.wpi.first.wpilibj
Class Ultrasonic

java.lang.Object
  edu.wpi.first.wpilibj.SensorBase
      edu.wpi.first.wpilibj.Ultrasonic

All Implemented Interfaces:

LiveWindowSendable, IDevice, ISensor, PIDSource, Sendable

public class Ultrasonic
extends SensorBase
implements PIDSource, ISensor, 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).

Ultrasonic

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

Create an instance of the Ultrasonic Sensor using the default module. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors. This constructor assumes that both digital I/O channels are in the default digital module.

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 using the default module. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors. This constructor assumes that both digital I/O channels are in the default digital module. 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.

Ultrasonic

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

Create an instance of the Ultrasonic sensor using specified modules. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors. This constructors takes the channel and module slot for each of the required digital I/O channels.

Parameters:

pingSlot - The digital module that the pingChannel is in.

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

echoSlot - The digital module that the echoChannel is in.

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 pingSlot,
                  int pingChannel,
                  int echoSlot,
                  int echoChannel)

Create an instance of the Ultrasonic sensor using specified modules. This is designed to supchannel the Daventech SRF04 and Vex ultrasonic sensors. This constructors takes the channel and module slot for each of the required digital I/O channels. Defualt unit is inches.

Parameters:

pingSlot - The digital module that the pingChannel is in.

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

echoSlot - The digital module that the echoChannel is in.

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.

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.

Returns:

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

getRangeMM

public double getRangeMM()

Get the range in millimeters from the ultrasonic sensor.

Returns:

double Range in millimeters of the target returned by the ultrasonic sensor. If there is no valid value yet, i.e. at least one measurement hasn't complted, then return 0.

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 String getSmartDashboardType()

Specified by:

getSmartDashboardType in interface Sendable

Returns:

the string representation of the named data type that will be used by the smart dashboard for this sendable

initTable

public void initTable(ITable subtable)

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()

Specified by:

getTable in interface Sendable

Returns:

the table that is currently associated with the sendable

updateTable

public void updateTable()

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

Specified by:

updateTable in interface LiveWindowSendable

startLiveWindowMode

public void startLiveWindowMode()

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()

Stop having this sendable object automatically respond to value changes.

Specified by:

stopLiveWindowMode in interface LiveWindowSendable