---

lejos.nxt.addon
Class NXTBee

java.lang.Object
  lejos.nxt.addon.NXTBee

All Implemented Interfaces:

Runnable

---

public class NXTBee
extends Object
implements Runnable

Send and receive data using a Dexter Industries NXTBee attached to Port 4 The NXTBee uses a RS485 serial link. By default it operates at 9600 baud, but this can be changed For more details on the NXTBee see: http://www.dexterindustries.com/NXTBee.html, The NXTBee class has two modes of operation; by default a thread can be started by calling the NXTBee nb = new NXTBee(); new Thread(nb).start(); The thread will act as a data pump continually polling the RS485 port and storing data received on the port in an internal circular buffer, and reading data from the circular buffer and writing it onto the RS485 port. Direct read/write access to the RS485 port is supported by calling the stop() and statrt() methods which pause the internal data reading thread. The NXTBee class returns an InputStream and an OutputStream object which can be used by programs to read and write data to and from the NXTBee. Use of the Stream objects is recommended over direct access to the RS485 port. For example, the standard DataInputStream/DataOutputStream classes provide a clean interface for reading/writing basic Java types. The NXTBee configuration is changed by entering a dedicated command mode by sending the sequence +++ with a one second pause before and after the +++ characters. In this mode the configuration of the NXTBee can be changed. To exit the command mode the sequence ATCN\n is sent. Portions of this class use code from Stephen Ostermiller's Java utilities: http://ostermiller.org/utils/CircularBuffer.html

Version:

0.1

Author:

Mark Crosbie ([email protected]), http://mastincrosbie.com/Marks_LEGO_projects/LEGO_Projects.html

---

Nested Class Summary
protected class	NXTBee.NXTBeeInputStream Class for reading from the NXTBee, returns a standard Java InputStream that can be used as an input source Based on CircularByteBuffer from Ostermiller Java utils.
protected class	NXTBee.NXTBeeOutputStream Class for writing to a circular byte buffer.

Field Summary
protected boolean	inputStreamClosed
protected boolean	outputStreamClosed

Constructor Summary
NXTBee() Default constructor initialises a NXTBee object at 9600 baud Enables the internal data reading thread
NXTBee(boolean runThread) Constuctor for the NXTBee running at default 9600 baud.
NXTBee(int baud) Constructor to create a NXTBee object at a specified baud rate
NXTBee(int baud, boolean runThread, boolean debugEnabled) Constructor to create a NXTBee object to communicate at a specified baud rate and to select if the internal data reading thread is running.

Method Summary
boolean	enterCommandMode() Force the NXTBee to go into a direct command mode.
boolean	exitCommandMode() Force the NXTBee to exit direct command mode.
InputStream	getInputStream() Return an Input stream for receiving data from the NXTBee
OutputStream	getOutputStream() Return an Output stream for writing to the NXTBee
int	read(byte[] b, int off, int len) Read bytes directly from the NXTBee RS485 buffer to get data if available Bypasses the internal circular buffer.
void	resetNXTBee() Reset the NXTBee to the default configuration See the NXTBee documentation for more details.
void	run() When an object implementing interface Runnable is used to create a thread, starting the thread causes the object's run method to be called in that separately executing thread.
void	saveConfiguration() Save the configuration on the device into FLASH so that it survives a power cycle See the NXTBee documentation for more details.
boolean	setNXTBeeBaudrate(int baud) Set the baud rate used by the NXTBee.
boolean	setPinmode() Set the D7 pin to the correct mode
void	start() Start the internal data reading thread, The data reading thread acts as a data pump to an internal circular buffer, filling the buffer with data received from the RS485 port, and sending data on the port when the buffer is filled.
void	stop() Stop the internal data reading thread, allowing direct access to the underlying sensor on port 4 The data reading thread acts as a data pump to an internal circular buffer, filling the buffer with data received from the RS485 port, and sending data on the port when the buffer is filled.
int	write(byte[] b, int offset, int len) Write bytes directly to the RS485 port for transmission by the NXTBee Bypasses the internal circular buffer.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

outputStreamClosed

protected boolean outputStreamClosed

---

inputStreamClosed

protected boolean inputStreamClosed

Constructor Detail

NXTBee

public NXTBee()

Default constructor initialises a NXTBee object at 9600 baud Enables the internal data reading thread

---

NXTBee

public NXTBee(boolean runThread)

Constuctor for the NXTBee running at default 9600 baud.

Parameters:

runThread - If true the internal data reading thread is started, if false the thread does not read/write data and all data transfer must be performed manually using the read/write methods.

---

NXTBee

public NXTBee(int baud,
              boolean runThread,
              boolean debugEnabled)

Constructor to create a NXTBee object to communicate at a specified baud rate and to select if the internal data reading thread is running.

Parameters:

baud - - baud rate to select when communicating with the NXTBee.

runThread - If true the internal data reading thread is started, if false the thread does not read/write data and all data transfer must be performed manually using the read/write methods.

debugEnabled - If true then debug output is written to RConsole. Can be disabled using the setDebug call. You must open RConsole to get any output on it first.

---

NXTBee

public NXTBee(int baud)

Constructor to create a NXTBee object at a specified baud rate

Parameters:

baud - Baud rate used to communicate with the NXTBee on port 4

Method Detail

getInputStream

public InputStream getInputStream()

Return an Input stream for receiving data from the NXTBee

Returns:

an input stream for the NXTBee

---

getOutputStream

public OutputStream getOutputStream()

Return an Output stream for writing to the NXTBee

Returns:

an output stream for the NXTBee

---

stop

public void stop()

Stop the internal data reading thread, allowing direct access to the underlying sensor on port 4 The data reading thread acts as a data pump to an internal circular buffer, filling the buffer with data received from the RS485 port, and sending data on the port when the buffer is filled. If you want to communicate directly with the NXTBee then call the stop() method to halt the buffer thread. Call start() to re-start the data reading thread. The contents of the circular data buffer are unaffected by calling start() and stop()

---

start

public void start()

Start the internal data reading thread, The data reading thread acts as a data pump to an internal circular buffer, filling the buffer with data received from the RS485 port, and sending data on the port when the buffer is filled. If you want to communicate directly with the NXTBee then call the stop() method to halt the buffer thread. Call start() to re-start the data reading thread. The contents of the circular data buffer are unaffected by calling start() and stop()

---

read

public int read(byte[] b,
                int off,
                int len)

Read bytes directly from the NXTBee RS485 buffer to get data if available Bypasses the internal circular buffer. It is not recommend to call this method if the internal data reading thread is running. The recommended method of calling is to first call stop(), then read(), then start() so as to avoid collisions between the data reading thread and this method.

Parameters:

b - - byte buffer to place the data into

off - - the offset in b to start storing data read into.

len - - the number of bytes to read. The contract of read is to read anywhere from 0 up to len bytes and store them in b[off]..b[off+len-1].

Returns:

The number of bytes read

---

write

public int write(byte[] b,
                 int offset,
                 int len)

Write bytes directly to the RS485 port for transmission by the NXTBee Bypasses the internal circular buffer. It is not recommend to call this method if the internal data reading thread is running. The recommended method of calling is to first call stop(), then write(), then start() so as to avoid collisions between the data reading thread and this method.

Parameters:

b - - the byte buffer to write data from

offset - - start writing bytes from the byte buffer at b[offset]

len - - write len bytes from b[offset] to the RS485 port

Returns:

The number of bytes written

---

run

public void run()

Description copied from interface: Runnable

When an object implementing interface Runnable is used to create a thread, starting the thread causes the object's run method to be called in that separately executing thread.

Specified by:

run in interface Runnable

---

enterCommandMode

public boolean enterCommandMode()

Force the NXTBee to go into a direct command mode. This mode bypasses the usual data exchange and allows the configuration of the NXTBee to be changed. To enter command mode the sequence +++ must be sent with a one-second guard on either side of the bytes. Once in command mode the NXTBee will not forward data received on the wireless antenna. To exit command mode call exitCommandMode(). Commands can be sent to the NXTBee using the write() method, or by calling hsWrite directly. The contents of the circular buffer are not read/written to the RS485 port while in command mode. However data can still be stored in the circular buffer for future transmission when command mode is exited.

Returns:

A boolean true if command mode entered successfully, else false

---

exitCommandMode

public boolean exitCommandMode()

Force the NXTBee to exit direct command mode. This mode reverts the NXTBee to normal operation where data sent and received on the RS485 port is transmitted over the wireless link. The character sequence to exit command mode is ATCN\n. If a OK reply is received then command mode is disabled and normal data reading resumes. If no OK is received then data reading/writing is not enabled and the NXTBee remains in command mode.

---

saveConfiguration

public void saveConfiguration()

Save the configuration on the device into FLASH so that it survives a power cycle See the NXTBee documentation for more details. You must call enterCommandMode() prior to calling this function.

---

resetNXTBee

public void resetNXTBee()

Reset the NXTBee to the default configuration See the NXTBee documentation for more details. You must call enterCommandMode() prior to calling this function

---

setPinmode

public boolean setPinmode()

Set the D7 pin to the correct mode

Returns:

True if the pin mode was set, else false

---

setNXTBeeBaudrate

public boolean setNXTBeeBaudrate(int baud)

Set the baud rate used by the NXTBee. This command will change the baud rate the NXTBee communicates at, so you will have to reset the baud rate that leJOS for the RS485 port by calling RS485.hsEnable() Supported baud rates are: 1200, 2400, 4800, 9600 (default), 19200, 38400, 57600, 115200 If a baud rate is selected that is not one of these values then no change is made to the baud rate of the NXTBee.

Parameters:

baud - The baud rate to set the the NXTBee to use. Can only be one of the values above

Returns:

True if the baud rate was set, else false

---