Package edu.wpi.first.hal.can

Class CANJNI

java.lang.Object

edu.wpi.first.hal.JNIWrapper

edu.wpi.first.hal.can.CANJNI

public class CANJNI
extends JNIWrapper

CAN API HAL JNI Functions.

See Also:

• "hal/CAN.h"

Nested Class Summary

Nested classes/interfaces inherited from class edu.wpi.first.hal.JNIWrapper

JNIWrapper.Helper

Field Summary

Fields

Modifier and Type	Field	Description
static final int	CAN_IS_FRAME_11BIT	Mask for "is frame 11 bits" in message ID.
static final int	CAN_IS_FRAME_REMOTE	Mask for "is frame remote" in message ID.
static final int	CAN_SEND_PERIOD_NO_REPEAT	Flag for sending a CAN message once.
static final int	CAN_SEND_PERIOD_STOP_REPEATING	Flag for stopping periodic CAN message sends.

Constructor Summary

Constructors

Constructor	Description
CANJNI()	Default constructor.

Method Summary

Modifier and Type	Method	Description
static void	closeCANStreamSession(int sessionHandle)	Closes a CAN stream session.
static void	getCANStatus(int busId, CANStatus status)	Retrieves the current status of the CAN bus.
static int	openCANStreamSession(int busId, int messageId, int messageIDMask, int maxMessages)	Opens a new CAN stream session for receiving CAN messages with specified filters.
static int	readCANStreamSession(int sessionHandle, CANStreamMessage[] messages, int messagesToRead)	Reads messages from a CAN stream session.
static int	receiveMessage(int busId, int messageId, CANReceiveMessage message)	Receives a CAN message.
static int	sendMessage(int busId, int messageId, byte[] data, int dataLength, int flags, int periodMs)	Sends a CAN message.

Methods inherited from class edu.wpi.first.hal.JNIWrapper

forceLoad, suppressUnused

Methods inherited from class java.lang.Object

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

Field Details

CAN_SEND_PERIOD_NO_REPEAT

public static final int CAN_SEND_PERIOD_NO_REPEAT

Flag for sending a CAN message once.

See Also:

• Constant Field Values

CAN_SEND_PERIOD_STOP_REPEATING

public static final int CAN_SEND_PERIOD_STOP_REPEATING

Flag for stopping periodic CAN message sends.

See Also:

• Constant Field Values

CAN_IS_FRAME_REMOTE

public static final int CAN_IS_FRAME_REMOTE

Mask for "is frame remote" in message ID.

See Also:

• Constant Field Values

CAN_IS_FRAME_11BIT

public static final int CAN_IS_FRAME_11BIT

Mask for "is frame 11 bits" in message ID.

See Also:

• Constant Field Values

Constructor Details

CANJNI

public CANJNI()

Default constructor.

Method Details

sendMessage

public static int sendMessage(int busId,
 int messageId,
 byte[] data,
 int dataLength,
 int flags,
 int periodMs)

Sends a CAN message.

Parameters:

busId - The bus ID.

messageId - The ID of the CAN message.

data - the data to send.

dataLength - the length of data to send

flags - the message flags

periodMs - The period in milliseconds at which to send the message, use CAN_SEND_PERIOD_NO_REPEAT for a single send.

Returns:

send status, 0 on success.

receiveMessage

public static int receiveMessage(int busId,
 int messageId,
 CANReceiveMessage message)

Receives a CAN message.

Parameters:

busId - The bus ID.

messageId - message id to look for.

message - The message.

Returns:

receive status, 0 on success.

getCANStatus

public static void getCANStatus(int busId,
 CANStatus status)

Retrieves the current status of the CAN bus.

Parameters:

busId - The bus ID.

status - The CANStatus object to hold the retrieved status.

openCANStreamSession

public static int openCANStreamSession(int busId,
 int messageId,
 int messageIDMask,
 int maxMessages)

Opens a new CAN stream session for receiving CAN messages with specified filters.

Parameters:

busId - The bus ID.

messageId - The CAN messageId to match against. The bits of the messageId are bitwise ANDed with the messageIDMask.

messageIDMask - The CAN messageIDMask is a bit-wise mask of bits in the messageId to match against. This allows matching against multiple frames. For example, providing an messageId of 0x2050001 and a mask of 0x1FFF003F would match all REV motor controller frames for a device with CAN ID 1. Providing a mask of 0x1FFFFFFF means that only the exact messageId will be matched. Providing a mask of 0 would match any frame of any type.

maxMessages - The maximum number of messages that can be buffered in the session.

Returns:

The handle to the opened CAN stream session.

closeCANStreamSession

public static void closeCANStreamSession(int sessionHandle)

Closes a CAN stream session.

Parameters:

sessionHandle - The handle of the CAN stream session to be closed.

readCANStreamSession

public static int readCANStreamSession(int sessionHandle,
 CANStreamMessage[] messages,
 int messagesToRead)
                                throws CANStreamOverflowException

Reads messages from a CAN stream session.

Parameters:

sessionHandle - The handle of the CAN stream session.

messages - An array to hold the CANStreamMessage objects (output parameter).

messagesToRead - The number of messages to read from the session.

Returns:

The number of messages read into the buffer

Throws:

CANStreamOverflowException - If the number of messages to read exceeds the capacity of the provided messages array.