Package edu.wpi.first.wpilibj

Class Ultrasonic

java.lang.Object
edu.wpi.first.wpilibj.Ultrasonic
All Implemented Interfaces:
Sendable, AutoCloseable
public class Ultrasonic
extends Object
implements Sendable, AutoCloseable
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 emitted. 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).

  • Constructor Details

    • Ultrasonic

      public Ultrasonic​(int pingChannel, int echoChannel)
      Create an instance of the Ultrasonic Sensor. This is designed to support 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.

    • 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.
      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 Details

    • getEchoChannel

      public int getEchoChannel()
      Returns the echo channel.
      Returns:
      The echo channel.

    • close

      public void close()
      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).
      Specified by:
      close in interface AutoCloseable

    • setAutomaticMode

      public static void setAutomaticMode​(boolean enabling)
      Turn Automatic mode on/off for all sensors.

      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 preferred, 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.

    • 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

    • initSendable

      public void initSendable​(SendableBuilder builder)
      Description copied from interface: Sendable
      Initializes this Sendable object.
      Specified by:
      initSendable in interface Sendable
      Parameters:
      builder - sendable builder