Package edu.wpi.first.wpilibj

Class CAN

java.lang.Object
edu.wpi.first.wpilibj.CAN
All Implemented Interfaces:
Closeable, AutoCloseable
public class CAN
extends Object
implements Closeable
High level class for interfacing with CAN devices conforming to the standard CAN spec.

No packets that can be sent gets blocked by the RoboRIO, so all methods work identically in all robot modes.

All methods are thread safe, however the CANData object passed into the read methods and the byte[] passed into the write methods need to not be modified for the duration of their respective calls.

  • Field Summary

    Fields 
    Modifier and Type Field Description
    static int kTeamDeviceType  
    static int kTeamManufacturer  

  • Constructor Summary

    Constructors 
    Constructor Description
    CAN​(int deviceId)
    Create a new CAN communication interface with the specific device ID.
    CAN​(int deviceId, int deviceManufacturer, int deviceType)
    Create a new CAN communication interface with a specific device ID, manufacturer and device type.

  • Method Summary

    Modifier and Type Method Description
    void close()
    Closes the CAN communication.
    static long getTimestampBaseTime()
    Reads the current value of the millisecond-resolution timer that CANData timestamps are based on.
    boolean readPacketLatest​(int apiId, CANData data)
    Read a CAN packet.
    boolean readPacketNew​(int apiId, CANData data)
    Read a new CAN packet.
    boolean readPacketTimeout​(int apiId, int timeoutMs, CANData data)
    Read a CAN packet.
    void stopPacketRepeating​(int apiId)
    Stop a repeating packet with a specific ID.
    void writePacket​(byte[] data, int apiId)
    Write a packet to the CAN device with a specific ID.
    int writePacketNoThrow​(byte[] data, int apiId)
    Write a packet to the CAN device with a specific ID.
    void writePacketRepeating​(byte[] data, int apiId, int repeatMs)
    Write a repeating packet to the CAN device with a specific ID.
    int writePacketRepeatingNoThrow​(byte[] data, int apiId, int repeatMs)
    Write a repeating packet to the CAN device with a specific ID.
    void writeRTRFrame​(int length, int apiId)
    Write an RTR frame to the CAN device with a specific ID.
    int writeRTRFrameNoThrow​(int length, int apiId)
    Write an RTR frame to the CAN device with a specific ID.

    Methods inherited from class java.lang.Object

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

  • Field Details

  • Constructor Details

    • CAN

      public CAN​(int deviceId)
      Create a new CAN communication interface with the specific device ID. This uses the team manufacturer and device types. The device ID is 6 bits (0-63).
      Parameters:
      deviceId - The device id

    • CAN

      public CAN​(int deviceId, int deviceManufacturer, int deviceType)
      Create a new CAN communication interface with a specific device ID, manufacturer and device type. The device ID is 6 bits, the manufacturer is 8 bits, and the device type is 5 bits.
      Parameters:
      deviceId - The device ID
      deviceManufacturer - The device manufacturer
      deviceType - The device type

  • Method Details

    • close

      public void close()
      Closes the CAN communication.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable

    • writePacket

      public void writePacket​(byte[] data, int apiId)
      Write a packet to the CAN device with a specific ID. This ID is 10 bits.
      Parameters:
      data - The data to write (8 bytes max)
      apiId - The API ID to write.

    • writePacketRepeating

      public void writePacketRepeating​(byte[] data, int apiId, int repeatMs)
      Write a repeating packet to the CAN device with a specific ID. This ID is 10 bits. The RoboRIO will automatically repeat the packet at the specified interval
      Parameters:
      data - The data to write (8 bytes max)
      apiId - The API ID to write.
      repeatMs - The period to repeat the packet at.

    • writeRTRFrame

      public void writeRTRFrame​(int length, int apiId)
      Write an RTR frame to the CAN device with a specific ID. This ID is 10 bits. The length by spec must match what is returned by the responding device
      Parameters:
      length - The length to request (0 to 8)
      apiId - The API ID to write.

    • writePacketNoThrow

      public int writePacketNoThrow​(byte[] data, int apiId)
      Write a packet to the CAN device with a specific ID. This ID is 10 bits.
      Parameters:
      data - The data to write (8 bytes max)
      apiId - The API ID to write.
      Returns:
      TODO

    • writePacketRepeatingNoThrow

      public int writePacketRepeatingNoThrow​(byte[] data, int apiId, int repeatMs)
      Write a repeating packet to the CAN device with a specific ID. This ID is 10 bits. The RoboRIO will automatically repeat the packet at the specified interval
      Parameters:
      data - The data to write (8 bytes max)
      apiId - The API ID to write.
      repeatMs - The period to repeat the packet at.
      Returns:
      TODO

    • writeRTRFrameNoThrow

      public int writeRTRFrameNoThrow​(int length, int apiId)
      Write an RTR frame to the CAN device with a specific ID. This ID is 10 bits. The length by spec must match what is returned by the responding device
      Parameters:
      length - The length to request (0 to 8)
      apiId - The API ID to write.
      Returns:
      TODO

    • stopPacketRepeating

      public void stopPacketRepeating​(int apiId)
      Stop a repeating packet with a specific ID. This ID is 10 bits.
      Parameters:
      apiId - The API ID to stop repeating

    • readPacketNew

      public boolean readPacketNew​(int apiId, CANData data)
      Read a new CAN packet. This will only return properly once per packet received. Multiple calls without receiving another packet will return false.
      Parameters:
      apiId - The API ID to read.
      data - Storage for the received data.
      Returns:
      True if the data is valid, otherwise false.

    • readPacketLatest

      public boolean readPacketLatest​(int apiId, CANData data)
      Read a CAN packet. This will continuously return the last packet received, without accounting for packet age.
      Parameters:
      apiId - The API ID to read.
      data - Storage for the received data.
      Returns:
      True if the data is valid, otherwise false.

    • readPacketTimeout

      public boolean readPacketTimeout​(int apiId, int timeoutMs, CANData data)
      Read a CAN packet. This will return the last packet received until the packet is older than the requested timeout. Then it will return false.
      Parameters:
      apiId - The API ID to read.
      timeoutMs - The timeout time for the packet
      data - Storage for the received data.
      Returns:
      True if the data is valid, otherwise false.

    • getTimestampBaseTime

      public static long getTimestampBaseTime()
      Reads the current value of the millisecond-resolution timer that CANData timestamps are based on.
      Returns:
      Current value of timer used as a base time for CANData timestamps in milliseconds