stamp.core
Class Uart

java.lang.Object
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  +--stamp.core.VirtualPeripheral
        |
        +--stamp.core.Uart

public class Uart

extends VirtualPeripheral

A virtual peripheral UART. Each instance of this class provides asynchronous serial communication in a single direction. For full-duplex communications create two Uart objects, one for each direction.

The Uart class uses 256 byte buffers for both transmit and receive. The buffer size is not configurable. If a handshaking pin is specified for a receive Uart then the peer will be signalled to stop transmitting when there are 16 bytes still free in the buffer.

Field Summary

static int	dirReceive The value to be using in the direction parameter to create a receiver.
static int	dirTransmit The value to be using in the direction parameter to create a transmitter.
static boolean	dontInvert The value for dataInvert and hsInvert to indicate that inverted logic should not be used.
static boolean	invert The value for dataInvert and hsInvert to indicate that inverted logic should be used.
static int	speed1200 The speed value for 1200 baud.
static int	speed14400 The speed value for 14400 baud.
static int	speed19200 The speed value for 19200 baud.
static int	speed2400 The speed value for 2400 baud.
static int	speed28800 The speed value for 28800 baud.
static int	speed38400 The speed value for 38400 baud.
static int	speed4800 The speed value for 4800 baud.
static int	speed57600 The speed value for 57600 baud.
static int	speed600 The speed value for 600 baud.
static int	speed7200 The speed value for 7200 baud.
static int	speed9600 The speed value for 9600 baud.
static int	stop1 Value to generate 1 stop bit.
static int	stop2 Value to generate 2 stop bits.
static int	stop3 Value to generate 3 stop bits.
static int	stop4 Value to generate 4 stop bits.
static int	stop5 Value to generate 5 stop bits.
static int	stop6 Value to generate 6 stop bits.
static int	stop7 Value to generate 7 stop bits.
static int	stop8 Value to generate 8 stop bits.

Constructor Summary

Uart(int direction, int dataPin, boolean dataInvert, int hsPin, boolean hsInvert, int baudRate, int stopBits)
Creates and initialises a new Uart for simplex communication using hardware (RTS/CTS) handshaking.

Uart(int direction, int dataPin, boolean dataInvert, int baudRate, int stopBits)
Creates and initialises a new Uart for simplex communication using no handshaking.

Uart(int direction, int dataPin, boolean dataInvert, int hsPin, int baudRate, int stopBits)
Creates and initialises a new Uart for simplex communication using hardware (RTS/CTS) handshaking.

Method Summary

boolean	byteAvailable() Test whether any bytes are available in the receive buffer.
int	receiveByte() Receives a byte from a receive Uart.
void	restart(int direction, int dataPin, boolean dataInvert, int hsPin, boolean hsInvert, int baudRate, int stopBits) Reinitialises a Uart for simplex communication using hardware (RTS/CTS) handshaking.
void	restart(int direction, int dataPin, boolean dataInvert, int baudRate, int stopBits) Reinitialises the Uart for simplex communication using no handshaking.
void	restart(int direction, int dataPin, boolean dataInvert, int hsPin, int baudRate, int stopBits) Reinitialises the Uart for simplex communication using hardware (RTS/CTS) handshaking.
boolean	sendBufferEmpty() Check space in the transmit buffer.
boolean	sendBufferFull() Check for space in the transmit buffer.
void	sendByte(int data) Adds a byte to the transmit buffer.
void	sendString(String data) Transmits a String.
void	setDirection(int direction) Change transmission direction.
void	start() Starts the Uart running.
void	stop() Stops the Uart.

Methods inherited from class java.lang.Object

equals

Field Detail

dirReceive

public static final int dirReceive

The value to be using in the direction parameter to create a receiver.

dirTransmit

public static final int dirTransmit

The value to be using in the direction parameter to create a transmitter.

speed600

public static final int speed600

The speed value for 600 baud.

speed1200

public static final int speed1200

The speed value for 1200 baud.

speed2400

public static final int speed2400

The speed value for 2400 baud.

speed4800

public static final int speed4800

The speed value for 4800 baud.

speed7200

public static final int speed7200

The speed value for 7200 baud.

speed9600

public static final int speed9600

The speed value for 9600 baud.

speed14400

public static final int speed14400

The speed value for 14400 baud.

speed19200

public static final int speed19200

The speed value for 19200 baud.

speed28800

public static final int speed28800

The speed value for 28800 baud.

speed38400

public static final int speed38400

The speed value for 38400 baud.

speed57600

public static final int speed57600

The speed value for 57600 baud.

invert

public static final boolean invert

The value for dataInvert and hsInvert to indicate that inverted logic should be used.

dontInvert

public static final boolean dontInvert

The value for dataInvert and hsInvert to indicate that inverted logic should not be used.

stop1

public static final int stop1

Value to generate 1 stop bit.

stop2

public static final int stop2

Value to generate 2 stop bits.

stop3

public static final int stop3

Value to generate 3 stop bits.

stop4

public static final int stop4

Value to generate 4 stop bits.

stop5

public static final int stop5

Value to generate 5 stop bits.

stop6

public static final int stop6

Value to generate 6 stop bits.

stop7

public static final int stop7

Value to generate 7 stop bits.

stop8

public static final int stop8

Value to generate 8 stop bits.

Constructor Detail

Uart

public Uart(int direction,
            int dataPin,
            boolean dataInvert,
            int baudRate,
            int stopBits)

Creates and initialises a new Uart for simplex communication using no handshaking. The constructor calls the start() method so the Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

Uart

public Uart(int direction,
            int dataPin,
            boolean dataInvert,
            int hsPin,
            int baudRate,
            int stopBits)

Creates and initialises a new Uart for simplex communication using hardware (RTS/CTS) handshaking. The constructor calls the start() method so the Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

hsPin - the pin to use for hardware handshaking.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

Uart

public Uart(int direction,
            int dataPin,
            boolean dataInvert,
            int hsPin,
            boolean hsInvert,
            int baudRate,
            int stopBits)

Creates and initialises a new Uart for simplex communication using hardware (RTS/CTS) handshaking. The constructor calls the start() method so the Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

hsPin - the pin to use for hardware handshaking.

hsInvert - whether the logic of the handshaking pin should be inverted or not.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

Method Detail

start

public void start()

Starts the Uart running. The constructor will start the Uart when it is first created. If it is later stopped with stop() then start() will start it again with the same set of parameters.

stop

public void stop()

Stops the Uart.

setDirection

public void setDirection(int direction)

Change transmission direction.

Parameters:

direction - new direction

restart

public void restart(int direction,
                    int dataPin,
                    boolean dataInvert,
                    int baudRate,
                    int stopBits)

Reinitialises the Uart for simplex communication using no handshaking. The Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

restart

public void restart(int direction,
                    int dataPin,
                    boolean dataInvert,
                    int hsPin,
                    int baudRate,
                    int stopBits)

Reinitialises the Uart for simplex communication using hardware (RTS/CTS) handshaking. The Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

hsPin - the pin to use for hardware handshaking.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

restart

public void restart(int direction,
                    int dataPin,
                    boolean dataInvert,
                    int hsPin,
                    boolean hsInvert,
                    int baudRate,
                    int stopBits)

Reinitialises a Uart for simplex communication using hardware (RTS/CTS) handshaking. The Uart will begin working immediately.

Parameters:

direction - whether the Uart is to be used transmit or receive mode. Valid options are Uart.dirTransmit and Uart.dirReceive.

dataPin - the Javelin Stamp I/O pin to use for sending or receiving data.

dataInvert - whether the data should be inverted or not. Valid options are Uart.invert and Uart.dontInvert.

hsPin - the pin to use for hardware handshaking

hsInvert - whether the logic of the handshaking pin should be inverted or not.

baudRate - the baud rate to use.

stopBits - the number of stop bits to use. Valid values are between Uart.stop1 and Uart.stop8.

sendBufferFull

public boolean sendBufferFull()

Check for space in the transmit buffer. If the VP is not install say that the buffer is full.

Returns:

transmit buffer is full

sendBufferEmpty

public boolean sendBufferEmpty()

Check space in the transmit buffer.

Returns:

transmit buffer is empty (and nothing being sent now)

sendByte

public void sendByte(int data)

Adds a byte to the transmit buffer. The byte is queued for transmit at the end of the buffer. If the buffer is already full then sendByte() will block until there is room in the buffer.

Parameters:

data - the data to transmit. Only the low 8 bits of the parameter are used.

sendString

public void sendString(String data)

Transmits a String.

Parameters:

data - the string to transmit.

receiveByte

public int receiveByte()

Receives a byte from a receive Uart. This method will block until a byte is available.

Returns:

the next byte in the receive buffer.

byteAvailable

public boolean byteAvailable()

Test whether any bytes are available in the receive buffer. Can also be used to test if the transmit buffer is empty.

Returns:

true if there is at least one byte available in the receive buffer, or at least one byte free in the transmit buffer.