com.dalsemi.comm
Class CanBus

java.lang.Object
  |
  +--com.dalsemi.comm.CanBus

public class CanBus

extends Object

Class allowing access to DS80C390 CAN Bus Controllers. Each controller can access 15 message centers numbered 1 - 15. Each message center can be programmed to either transmit or receive, except message center 15. Message center 15 can only receive (not transmit) and can also buffer two back-to-back frames.
With an 18.432MHz system clock, CAN bit rates of 20, 50, and 125Kbps can be achieved.

         Prescaler  tqu      tseg1   tseg2
 20Kbps  71         3.852us  5       7
 50Kbps  41         2.224us  3       5
 125Kbps 7          3.798us  13      7
 

See Also:

CanFrame

Field Summary

static byte	CANBUS0 Passed to constructor to create object to access CAN Bus 0
static byte	CANBUS1 Passed to constructor to create object to access CAN Bus 1

Constructor Summary

CanBus(byte portnum)
Creates a new CanBus instance on the specified port.

Method Summary

void	autoAnswerRemoteFrameRequest(int messageCenter, int ID, byte[] data) Sets up a message center to auto reply to remote frame requests.
void	close() Closes this CAN Bus Controller.
void	disableController() Shuts down this CAN controller.
void	disableMessageCenter(int messageCenter) Shuts down this message center for changes.
void	enableController() Starts up this CAN controller, and connects to the bus.
void	enableControllerPassive() Starts up this CAN controller, but doesn't connect CAN transmit to the bus.
void	enableMessageCenter(int messageCenter) Starts up this message center.
int	getRXErrorCount() Gets the receiver error count.
int	getTXErrorCount() Gets the transmitter error count.
void	open() Opens this CAN Bus Controller.
void	receive(CanFrame frame) Receives a CAN data frame.
int	receiveFramesAvailable() Gets number of frames in the receive queue.
boolean	receivePoll(CanFrame frame) Receives a CAN data frame.
void	resetController() Resets this CAN controller.
void	sendDataFrame(int ID, boolean extendedID, byte[] data) Sends a CAN Data Frame from first available message center without using an explicit CanFrame.
void	sendFrame(CanFrame frame) Sends a CAN frame from first available message center.
void	sendRemoteFrameRequest(int ID, boolean extendedID, byte[] data) Sends a CAN Remote Frame Request from first available message center without using an explicit CanFrame.
void	set11BitGlobalIDMask(int mask) Sets the 11 Bit (STANDARD) Global ID Mask.
void	set11BitMessageCenterArbitrationID(int messageCenter, int ID) Sets an 11 Bit Arbitration ID for a message center.
void	set29BitGlobalIDMask(int mask) Sets the 29 Bit (EXTENDED) Global ID Mask.
void	set29BitMessageCenter15IDMask(int mask) Sets the 29 Bit Message Center 15 ID Mask.
void	set29BitMessageCenterArbitrationID(int messageCenter, int ID) Sets a 29 Bit Arbitration ID for a message center.
void	setBaudRatePrescaler(int prescaler) Sets the baud rate prescaler from the CPU crystal.
void	setMessageCenterMessageIDMaskEnable(int messageCenter, boolean maskEnable) Enables or disables Message ID Masking for a specific message center.
void	setMessageCenterRXMode(int messageCenter) Sets a specific message center as receiver.
void	setMessageCenterTXMode(int messageCenter) Sets a specific message center as transmitter.
void	setMessageCenterWriteOverEnable(int messageCenter, boolean writeover) Sets the state of write over in a specific message center.
void	setReceiveQueueLimit(int numframes) Sets receive queue frame limit.
void	setSampleRate(int sampleRate) Sets SMP (Sample Rate) which is whether to use one or three samples per bit time during CAN communication.
void	setSiestaMode() Puts the CAN Controller in SIESTA (low power) mode.
void	setSynchronizationJumpWidth(int jumpWidth) Sets the SJW (Synchronization Jump Width) necessary for adjusting TSEG1 and TSEG2 to compensate for sync problems during CAN communication.
void	setTransmitQueueLimit(int numframes) Sets transmit queue frame limit.
void	setTSEG1(int tseg1) Sets TSEG1 (Timing Segment 1 = PROP_SEG + PHASE_SEG1) to a specified number of time quanta.
void	setTSEG2(int tseg2) Sets TSEG2 (Timing Segment 2 = PHASE_SEG2) to a specified number of time quanta.

Methods inherited from class java.lang.Object

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

Field Detail

CANBUS0

public static final byte CANBUS0

Passed to constructor to create object to access CAN Bus 0

CANBUS1

public static final byte CANBUS1

Passed to constructor to create object to access CAN Bus 1

Constructor Detail

CanBus

public CanBus(byte portnum)
       throws CanBusException

Creates a new CanBus instance on the specified port. This opens and resets the specified CAN Controller and readies it for operation. The controller will be in a disabled state. Calling enableController will place the controller on the bus. All message centers start up disabled.

Parameters:

portnum - either CANBUS0 or CANBUS1

Throws:

CanBusException - if port is already open, or the controller will not reset

Method Detail

open

public void open()
          throws CanBusException

Opens this CAN Bus Controller. Assigns ownership of the controller to the calling process. The constructor calls this automatically when a new CanBus object is created.

Throws:

CanBusException - if controller is already open

close

public void close()
           throws CanBusException

Closes this CAN Bus Controller. Reliquishes ownership of the controller and releases all resources for this CAN controller.

Throws:

CanBusException - if controller is not open

setBaudRatePrescaler

public void setBaudRatePrescaler(int prescaler)
                          throws CanBusException

Sets the baud rate prescaler from the CPU crystal. This method sets the basic time quantum (tqu) necessary for CAN communication. The divisor divides straight off the external crystal on the processor.
For instance, at 18.432MHz, a divisor of 7 will give you a tqu of 379.774ns.
tqu = 7 * 1/18.432MHz

Parameters:

prescaler - 1 to 256

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if prescaler is out of range

setSynchronizationJumpWidth

public void setSynchronizationJumpWidth(int jumpWidth)
                                 throws CanBusException

Sets the SJW (Synchronization Jump Width) necessary for adjusting TSEG1 and TSEG2 to compensate for sync problems during CAN communication.
TSEG1 may be lengthened during resync.
TSEG2 may be shortened during resync.

Parameters:

jumpWidth - 1 to 4 (1tqu to 4tqu)

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if SJW is out of range

setSampleRate

public void setSampleRate(int sampleRate)
                   throws CanBusException

Sets SMP (Sample Rate) which is whether to use one or three samples per bit time during CAN communication.

Parameters:

sampleRate - 1 or 3

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if SMP is out of range

setTSEG1

public void setTSEG1(int tseg1)
              throws CanBusException

Sets TSEG1 (Timing Segment 1 = PROP_SEG + PHASE_SEG1) to a specified number of time quanta. This is the timing segment before the bit sample.

Parameters:

tseg1 - 2 to 16 (2tqu to 16tqu)

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if TSEG1 is out of range

setTSEG2

public void setTSEG2(int tseg2)
              throws CanBusException

Sets TSEG2 (Timing Segment 2 = PHASE_SEG2) to a specified number of time quanta. This is the timing segment after the bit sample.

Parameters:

tseg2 - 2 to 8 (2tqu to 8tqu)

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if TSEG2 is out of range

resetController

public void resetController()
                     throws CanBusException

Resets this CAN controller. No more transmissions, or receptions will be processed. The CAN controller is disconnected from the bus. All message centers reset to power on defaults.
ALL SETTINGS WILL BE LOST!

Throws:

CanBusException - if controller is not open

disableController

public void disableController()
                       throws CanBusException

Shuts down this CAN controller. No more transmissions, or receptions will be processed. The CAN controller is disconnected from the bus. User is free to change timing and other communication critical parameters. Message centers remain intact.

Throws:

CanBusException - if controller is not open

enableController

public void enableController()
                      throws CanBusException

Starts up this CAN controller, and connects to the bus. All critical timing parameters must already be set. Message centers remain intact.

Throws:

CanBusException - if controller is not open

enableControllerPassive

public void enableControllerPassive()
                             throws CanBusException

Starts up this CAN controller, but doesn't connect CAN transmit to the bus. Become a quiet listener on the bus. All critical timing parameters must already be set. Message centers remain intact.

Throws:

CanBusException - if controller is not open

enableMessageCenter

public void enableMessageCenter(int messageCenter)
                         throws CanBusException

Starts up this message center. All mode changes must be complete. Message center becomes operational and able to send or receive messages depending on mode.

Parameters:

messageCenter - message center to enable

Throws:

CanBusException - if controller is not open

disableMessageCenter

public void disableMessageCenter(int messageCenter)
                          throws CanBusException

Shuts down this message center for changes. No more transmissions, or receptions will be processed at this message center.

Parameters:

messageCenter - message center to enable

Throws:

CanBusException - if controller is not open

setReceiveQueueLimit

public void setReceiveQueueLimit(int numframes)
                          throws CanBusException

Sets receive queue frame limit. If the limit is set to zero, reads will block until a frame is received, or bus error. Maximum limit is 255 frames.

Parameters:

numframes - maximum number of frames to store in queue

Throws:

CanBusException - if controller is not open, or if queue could not be allocated

IllegalArgumentException - if number of frames is out of range

receiveFramesAvailable

public int receiveFramesAvailable()
                           throws CanBusException

Gets number of frames in the receive queue. If the receive queue limit is set to zero, the return value will be zero.

Returns:

number of frames pending in receive queue

Throws:

CanBusException - if controller is not open

receive

public void receive(CanFrame frame)
             throws CanBusException

Receives a CAN data frame. This method blocks until a frame is received.

Parameters:

frame - a frame in which to place the incoming data

Throws:

CanBusException - if controller is not open, or if bus error occurs

receivePoll

public boolean receivePoll(CanFrame frame)
                    throws CanBusException

Receives a CAN data frame. This method returns immediately and does not block.

Parameters:

frame - frame in which to place the incoming data

Returns:

true if frame has been received

Throws:

CanBusException - if controller is not open, or if bus error occurs

setTransmitQueueLimit

public void setTransmitQueueLimit(int numframes)
                           throws CanBusException

Sets transmit queue frame limit. If the limit is set to zero, writes will block until frame is transmitted, or bus error. Maximum limit is 255 frames.

Parameters:

numframes - maximum number of frames to store in queue

Throws:

CanBusException - if controller is not open

IllegalArgumentException - if number of frames is out of range

sendFrame

public void sendFrame(CanFrame frame)
               throws CanBusException

Sends a CAN frame from first available message center. If transmit queue size is one, this method will block until the message has been successfully transmitted, or an error has occurred. If transmit queue size is greater than one, messages will be queued for transmit and method will return immediately.

Parameters:

frame - frame to send

Throws:

CanBusException - if controller is not open, or if bus error occurs

sendDataFrame

public void sendDataFrame(int ID,
                          boolean extendedID,
                          byte[] data)
                   throws CanBusException

Sends a CAN Data Frame from first available message center without using an explicit CanFrame. If transmit queue size is one, this method will block until the message has been successfully transmitted, or an error has occurred. If transmit queue size is greater than one, messages will be queued for transmit and method will return immediately.

Parameters:

ID - 11 or 29 bit ID for frame

extendedID - true for extended ID (29 bit), or false for standard ID (11 bit)

data - to send in frame (max 8 bytes)

Throws:

CanBusException - if controller is not open, or if bus error occurs

sendRemoteFrameRequest

public void sendRemoteFrameRequest(int ID,
                                   boolean extendedID,
                                   byte[] data)
                            throws CanBusException

Sends a CAN Remote Frame Request from first available message center without using an explicit CanFrame. If transmit queue size is one, this method will block until the message has been successfully transmitted, or an error has occurred. If transmit queue size is greater than one, messages will be queued for transmit and method will return immediately.

Parameters:

ID - 11 or 29 bit ID for frame

extendedID - true for extended ID (29 bit), or false for standard ID (11 bit)

data - to send in frame (max 8 bytes)

Throws:

CanBusException - if controller is not open, or if bus error occurs

autoAnswerRemoteFrameRequest

public void autoAnswerRemoteFrameRequest(int messageCenter,
                                         int ID,
                                         byte[] data)
                                  throws CanBusException

Sets up a message center to auto reply to remote frame requests.
Note: This resets the state of a message center for this purpose only. Also, the message center becomes enabled during this method.

Parameters:

messageCenter - message center to use for this reply

ID - 11 or 29 bit ID for frame

data - to send in frame (max 8 bytes)

Throws:

CanBusException - if controller is not open, or if bus error occurs

set11BitGlobalIDMask

public void set11BitGlobalIDMask(int mask)
                          throws CanBusException

Sets the 11 Bit (STANDARD) Global ID Mask. The Global ID Mask is used to denote which bits to match in the incoming frame ID.

Parameters:

mask - 11 bit mask

Throws:

CanBusException - if controller is not open, or if bus error occurs

set29BitGlobalIDMask

public void set29BitGlobalIDMask(int mask)
                          throws CanBusException

Sets the 29 Bit (EXTENDED) Global ID Mask. The Global ID Mask is used to denote which bits to match in the incoming frame ID.

Parameters:

mask - 29 bit mask

Throws:

CanBusException - if controller is not open, or if bus error occurs

set29BitMessageCenter15IDMask

public void set29BitMessageCenter15IDMask(int mask)
                                   throws CanBusException

Sets the 29 Bit Message Center 15 ID Mask. Message Center 15 has it's own ID Mask. The Message Center 15 ID Mask is used to denote which bits to match in the Message Center 15 ID.

Parameters:

mask - 29 bit mask

Throws:

CanBusException - if controller is not open, or if bus error occurs

set11BitMessageCenterArbitrationID

public void set11BitMessageCenterArbitrationID(int messageCenter,
                                               int ID)
                                        throws CanBusException

Sets an 11 Bit Arbitration ID for a message center. When this value matches an incoming frame ID subject to the Global ID Mask or Message Center 15 Mask, the incoming frame will be received.
Note: This will change the specified message center to only respond to 11 bit messages.

Parameters:

messageCenter - message center to change

ID - 11 bit ID

Throws:

CanBusException - if controller is not open, or if bus error occurs

set29BitMessageCenterArbitrationID

public void set29BitMessageCenterArbitrationID(int messageCenter,
                                               int ID)
                                        throws CanBusException

Sets a 29 Bit Arbitration ID for a message center. When this value matches an incoming frame ID subject to the Global ID Mask or Message Center 15 Mask, the incoming frame will be received.
Note: This will change the specified message center to only respond to 29 bit messages.

Parameters:

messageCenter - message center to change

ID - 29 bit ID

Throws:

CanBusException - if controller is not open, or if bus error occurs

setMessageCenterWriteOverEnable

public void setMessageCenterWriteOverEnable(int messageCenter,
                                            boolean writeover)
                                     throws CanBusException

Sets the state of write over in a specific message center. This allows incoming frames to overwrite received frames that haven't been moved out of the message center.

Parameters:

messageCenter - message center to change

writeover - set to true to allow overwrite.

Throws:

CanBusException - if controller is not open, or if bus error occurs

setMessageCenterTXMode

public void setMessageCenterTXMode(int messageCenter)
                            throws CanBusException

Sets a specific message center as transmitter.
Note: Message Center 15 is always RECEIVE only.

Parameters:

messageCenter - message center to change

Throws:

CanBusException - if controller is not open, or if bus error occurs

IllegalArgumentException - if message center is out of range

setMessageCenterRXMode

public void setMessageCenterRXMode(int messageCenter)
                            throws CanBusException

Sets a specific message center as receiver.
Note: Message Center 15 is always RECEIVE only.

Parameters:

messageCenter - message center to change

Throws:

CanBusException - if controller is not open, or if bus error occurs

setMessageCenterMessageIDMaskEnable

public void setMessageCenterMessageIDMaskEnable(int messageCenter,
                                                boolean maskEnable)
                                         throws CanBusException

Enables or disables Message ID Masking for a specific message center.
Note: If masking is disabled, this message center ID must match ALL bits of incoming ID.

Parameters:

messageCenter - message center to change

maskEnable - true to allow Global Mask, false to require exact match of ID

Throws:

CanBusException - if controller is not open, or if bus error occurs

getTXErrorCount

public int getTXErrorCount()
                    throws CanBusException

Gets the transmitter error count.

Returns:

transmitter error count

Throws:

CanBusException - if controller is not open, or if bus error occurs

getRXErrorCount

public int getRXErrorCount()
                    throws CanBusException

Gets the receiver error count.

Returns:

receiver error count

Throws:

CanBusException - if controller is not open, or if bus error occurs

setSiestaMode

public void setSiestaMode()
                   throws CanBusException

Puts the CAN Controller in SIESTA (low power) mode. When Bus activity is detected, the controller will wake up and participate on the bus.

Throws:

CanBusException - if controller is not open, or if bus error occurs