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 final int
    kTeamDeviceType
    Team device type.
    static final int
    kTeamManufacturer
    Team manufacturer.

  • Constructor Summary

    Constructors
    Constructor
    Description
    CAN(int busId, int deviceId)
    Create a new CAN communication interface with the specific device ID.
    CAN(int busId, 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.
    boolean
    readPacketLatest(int apiId, CANReceiveMessage data)
    Read a CAN packet.
    boolean
    readPacketNew(int apiId, CANReceiveMessage data)
    Read a new CAN packet.
    boolean
    readPacketTimeout(int apiId, CANReceiveMessage data, int timeoutMs)
    Read a CAN packet.
    void
    stopPacketRepeating(int apiId)
    Stop a repeating packet with a specific ID.
    void
    writePacket(int apiId, byte[] data, int dataLength, int flags)
    Write a packet to the CAN device with a specific ID.
    int
    writePacketNoThrow(int apiId, byte[] data, int dataLength, int flags)
    Write a packet to the CAN device with a specific ID.
    void
    writePacketRepeating(int apiId, byte[] data, int dataLength, int flags, int repeatMs)
    Write a repeating packet to the CAN device with a specific ID.
    int
    writePacketRepeatingNoThrow(int apiId, byte[] data, int dataLength, int flags, int repeatMs)
    Write a repeating packet to the CAN device with a specific ID.
    void
    writeRTRFrame(int apiId, byte[] data, int dataLength, int flags)
    Write an RTR frame to the CAN device with a specific ID.
    int
    writeRTRFrameNoThrow(int apiId, byte[] data, int dataLength, int flags)
    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 busId, 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:
      busId - The bus ID
      deviceId - The device id

    • CAN

      public CAN(int busId, 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:
      busId - The bus ID
      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(int apiId, byte[] data, int dataLength, int flags)
      Write a packet to the CAN device with a specific ID. This ID is 10 bits.
      Parameters:
      apiId - The API ID to write.
      data - The data to write
      dataLength - The data length
      flags - The flags

    • writePacketRepeating

      public void writePacketRepeating(int apiId, byte[] data, int dataLength, int flags, 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:
      apiId - The API ID to write.
      data - The data to write
      dataLength - The data length
      flags - The flags
      repeatMs - The period to repeat the packet at.

    • writeRTRFrame

      public void writeRTRFrame(int apiId, byte[] data, int dataLength, int flags)
      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:
      apiId - The API ID to write.
      data - The data to write
      dataLength - The data length
      flags - The flags

    • writePacketNoThrow

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

    • writePacketRepeatingNoThrow

      public int writePacketRepeatingNoThrow(int apiId, byte[] data, int dataLength, int flags, 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:
      apiId - The API ID to write.
      data - The data to write
      dataLength - The data length
      flags - The flags
      repeatMs - The period to repeat the packet at.
      Returns:
      TODO

    • writeRTRFrameNoThrow

      public int writeRTRFrameNoThrow(int apiId, byte[] data, int dataLength, int flags)
      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:
      apiId - The API ID to write.
      data - The data to write
      dataLength - The data length
      flags - The flags
      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, CANReceiveMessage 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, CANReceiveMessage 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, CANReceiveMessage data, int timeoutMs)
      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.