jdk.dio.uart

Interface UART

All Superinterfaces:

java.lang.AutoCloseable, BufferAccess<java.nio.ByteBuffer>, java.nio.channels.ByteChannel, java.nio.channels.Channel, java.io.Closeable, Device<UART>, java.nio.channels.ReadableByteChannel, java.nio.channels.WritableByteChannel

All Known Subinterfaces:

ModemUART

public interface UART
extends Device<UART>, java.nio.channels.ByteChannel, BufferAccess<java.nio.ByteBuffer>

The UART interface provides methods for controlling and accessing a UART (Universal Asynchronous Receiver/Transmitter).

A UART device may be identified by the numerical ID and by the name (if any defined) that correspond to its registered configuration. A UART instance can be opened by a call to one of the DeviceManager.open(id,...) methods using its ID or by a call to one of the DeviceManager.open(name,...) methods using its name. When a UART instance is opened with an ad-hoc UARTConfig configuration (which includes its hardware addressing information) using one of the DeviceManager.open(config,...) it is not assigned any ID nor name.

Once opened, an application can read the received data bytes and write the data bytes to be transmitted through the UART using methods of the ByteChannel interface.

An application can register a UARTEventListener instance which will get asynchronously notified of input data availability, input buffer overrun and/or empty output buffer conditions. Note that the input and output buffers for which these events may be notified may not necessarily correspond to the transmit and receive FIFO buffers of the UART hardware but may be buffers allocated by the underlying native driver. To register a UARTEventListener instance, the application must call the setEventListener method. The registered listener can later on be removed by calling the same method with a null listener parameter.

When done, an application should call the UART.close method to close the UART. Any further attempt to access or control a UART which has been closed will result in a ClosedDeviceException been thrown.

See Also:

UARTPermission, ClosedDeviceException

Field Summary

Fields inherited from interface jdk.dio.Device

BIG_ENDIAN, LITTLE_ENDIAN, MIXED_ENDIAN

Method Summary

Methods

Modifier and Type	Method and Description
void	generateBreak(int duration) Generates a break condition for the specified duration.
int	getBaudRate() Gets the current baud rate.
int	getDataBits() Gets the current number of bits per character.
int	getParity() Gets the current parity.
int	getReceiveTimeout() Gets the current receive timeout.
int	getReceiveTriggerLevel() Gets the current receive trigger level.
int	getStopBits() Gets the current number of stop bits per character.
int	read(java.nio.ByteBuffer dst) Reads a sequence of bytes from this UART into the given buffer.
void	setBaudRate(int baudRate) Sets the baud rate.
void	setDataBits(int dataBits) Sets the number of bits per character.
void	setEventListener(int eventId, UARTEventListener listener) Registers a UARTEventListener instance to monitor input data availability, input buffer overrun and/or empty output buffer conditions.
void	setParity(int parity) Sets the parity.
void	setReceiveTimeout(int timeout) Sets the receive timeout.
void	setReceiveTriggerLevel(int level) Sets the receive trigger level.
void	setStopBits(int stopBits) Sets the number of stop bits per character.
void	startReading(java.nio.ByteBuffer dst1, java.nio.ByteBuffer dst2, InputRoundListener<UART,java.nio.ByteBuffer> listener) Starts asynchronous reading in successive rounds.
void	startReading(java.nio.ByteBuffer dst, InputRoundListener<UART,java.nio.ByteBuffer> listener) Starts asynchronous reading in successive rounds - reading data into the provided buffer.
void	startWriting(java.nio.ByteBuffer src1, java.nio.ByteBuffer src2, OutputRoundListener<UART,java.nio.ByteBuffer> listener) Starts asynchronous writing in successive rounds.
void	startWriting(java.nio.ByteBuffer src, OutputRoundListener<UART,java.nio.ByteBuffer> listener) Starts asynchronous writing in successive rounds - initially writing the data remaining in the provided buffer.
void	stopReading() Stops (cancels) the currently active reading session.
void	stopWriting() Stops (cancels) the currently active writing session.
int	write(java.nio.ByteBuffer src) Writes a sequence of bytes to this UART from the given buffer.

Methods inherited from interface jdk.dio.Device

close, getDescriptor, isOpen, tryLock, unlock

Methods inherited from interface jdk.dio.BufferAccess

getInputBuffer, getOutputBuffer

Method Detail

getBaudRate

int getBaudRate()
                throws java.io.IOException,
                       UnavailableDeviceException,
                       ClosedDeviceException

Gets the current baud rate. If the baud rate was not set previously using setBaudRate the device configuration-specific default value is returned.

Returns:

the current baud rate.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

getDataBits

int getDataBits()
                throws java.io.IOException,
                       UnavailableDeviceException,
                       ClosedDeviceException

Gets the current number of bits per character.

Returns:

the number bits per character: UARTConfig.DATABITS_5, UARTConfig.DATABITS_6, UARTConfig.DATABITS_7, UARTConfig.DATABITS_8 or UARTConfig.DATABITS_9.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

getParity

int getParity()
              throws java.io.IOException,
                     UnavailableDeviceException,
                     ClosedDeviceException

Gets the current parity.

Returns:

the speed parity: UARTConfig.PARITY_ODD, UARTConfig.PARITY_EVEN, UARTConfig.PARITY_MARK, UARTConfig.PARITY_SPACE, or UARTConfig.PARITY_NONE.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

getStopBits

int getStopBits()
                throws java.io.IOException,
                       UnavailableDeviceException,
                       ClosedDeviceException

Gets the current number of stop bits per character.

Returns:

the number of stop bits per character: UARTConfig.STOPBITS_1, UARTConfig.STOPBITS_1_5, or UARTConfig.STOPBITS_2.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

setBaudRate

void setBaudRate(int baudRate)
                 throws java.io.IOException,
                        UnavailableDeviceException,
                        ClosedDeviceException

Sets the baud rate.

Parameters:

baudRate - the baud rate to set.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested baud rate.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

setDataBits

void setDataBits(int dataBits)
                 throws java.io.IOException,
                        UnavailableDeviceException,
                        ClosedDeviceException

Sets the number of bits per character.

Parameters:

dataBits - the number bits per character: UARTConfig.DATABITS_5, UARTConfig.DATABITS_6, UARTConfig.DATABITS_7, UARTConfig.DATABITS_8 or UARTConfig.DATABITS_9.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested number of bits per character.

java.lang.IllegalArgumentException - if dataBits is not one of the defined values.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

setEventListener

void setEventListener(int eventId,
                    UARTEventListener listener)
                      throws java.io.IOException,
                             UnavailableDeviceException,
                             ClosedDeviceException

Registers a UARTEventListener instance to monitor input data availability, input buffer overrun and/or empty output buffer conditions. While the listener can be triggered by hardware interrupts, there are no real-time guarantees of when the listener will be called.

A list of event type IDs is defined in UARTEvent.

If this UART is open in DeviceManager.SHARED access mode the listeners registered by all the applications sharing the underlying device will get notified of the events they registered for.

If listener is null then listener previously registered for the specified event type will be removed.

Only one listener can be registered at a particular time for a particular event type.

Parameters:

eventId - ID of the native event to listen to: UARTEvent.INPUT_DATA_AVAILABLE, UARTEvent.INPUT_BUFFER_OVERRUN, UARTEvent.OUTPUT_BUFFER_EMPTY, UARTEvent.BREAK_INTERRUPT, UARTEvent.FRAMING_ERROR or UARTEvent.PARITY_ERROR.

listener - the UARTEventListener instance to be notified upon occurrence of the designated event.

Throws:

java.lang.IllegalArgumentException - if eventId does not correspond to any of the supported event types.

java.lang.IllegalStateException - if listener is not null and a listener is already registered for the specified event type.

ClosedDeviceException - if the device has been closed.

java.lang.UnsupportedOperationException - if this UART does not support asynchronous event notification of the requested conditions (eg. input data availability, input buffer overrun, empty output buffer and/or error conditions).

java.io.IOException - if some other I/O error occurs.

UnavailableDeviceException

setParity

void setParity(int parity)
               throws java.io.IOException,
                      UnavailableDeviceException,
                      ClosedDeviceException

Sets the parity.

Parameters:

parity - the speed parity: UARTConfig.PARITY_ODD, UARTConfig.PARITY_EVEN, UARTConfig.PARITY_MARK, UARTConfig.PARITY_SPACE, or UARTConfig.PARITY_NONE.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested parity.

java.lang.IllegalArgumentException - if parity is not one of the defined values.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

setStopBits

void setStopBits(int stopBits)
                 throws java.io.IOException,
                        UnavailableDeviceException,
                        ClosedDeviceException

Sets the number of stop bits per character.

Parameters:

stopBits - the number of stop bits per character: UARTConfig.STOPBITS_1, UARTConfig.STOPBITS_1_5, or UARTConfig.STOPBITS_2.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested number of stop bits per character.

java.lang.IllegalArgumentException - if stopBits is not one of the defined values.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

startWriting

void startWriting(java.nio.ByteBuffer src,
                OutputRoundListener<UART,java.nio.ByteBuffer> listener)
                  throws java.io.IOException,
                         UnavailableDeviceException,
                         ClosedDeviceException

Starts asynchronous writing in successive rounds - initially writing the data remaining in the provided buffer. Additional rounds are asynchronously fetched by notifying the provided OutputRoundListener instance once the initial data have been written. The initial data to be written is retrieved from the provided buffer; the data to write during the subsequent rounds is retrieved from that very same buffer upon invocation of the provided OutputRoundListener instance.

Writing can be stopped by a call to stopWriting.

r bytes will be written to this UART, where r is the number of bytes remaining in the buffer (possibly 0), that is, src.remaining(), at the moment this method is initially invoked and then subsequently when the listener is returning.

Suppose that a byte sequence of length n is written, where 0 <= n <= r. This byte sequence will be transferred from the buffer starting at index p, where p is the buffer's position at the moment this method is initially invoked and then subsequently when the listener is returning; the index of the last byte written will be p + n - 1. Upon invocation of the listener for fetching more data to write the buffer's position will be equal to p + n; its limit will not have changed.
The buffer's position upon stopping this asynchronous operation by a call to stopWriting is not predictable unless called from within the listener.

The data will be written according to the current baud rate as returned by getBaudRate. The baud rate and other configuration parameters can be changed by the provided OutputRoundListener instance upon notification of each round.

Note that a buffer with 0 bytes remaining to be written (that is a buffer already empty), at the moment this method is initially invoked or then subsequently when the listener is returning will not stop the asynchronous operation; the listener is guaranteed to be called back again at the latest as soon as all other events pending at the time of notification have been dispatched.

Interfering with the asynchronous operation by accessing and modifying the provided buffer concurrently may yield unpredictable results.

Only one write operation (synchronous or asynchronous) can be going on at any time.
Note therefore that while empty output buffer conditions (UARTEvent.OUTPUT_BUFFER_EMPTY) may be notified to the registered UARTEventListener independently to the invocation of the provided OutputRoundListener attempting to call the write method from within the registered UARTEventListener will result in an exception.

Parameters:

src - the buffer for the data to be written.

listener - the OutputRoundListener instance to be notified when the all the data remaining in the buffer has been written.

Throws:

java.lang.NullPointerException - If src or listener is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.lang.IllegalStateException - if another synchronous or asynchronous output operation is already active.

java.io.IOException - if some other I/O error occurs such as the device is not writable.

startWriting

void startWriting(java.nio.ByteBuffer src1,
                java.nio.ByteBuffer src2,
                OutputRoundListener<UART,java.nio.ByteBuffer> listener)
                  throws java.io.IOException,
                         UnavailableDeviceException,
                         ClosedDeviceException

Starts asynchronous writing in successive rounds.

This method behaves identically to startWriting(ByteBuffer, OutputRoundListener) excepts that it uses double-buffering. Notification will happen when all the data remaining in the current working buffer (initially src1) has been written and writing will proceed with the alternate buffer (which will become the current working buffer). Writing will only be suspended if the previous event has not yet been handled.

Note that a working buffer with 0 bytes remaining to be written (that is a buffer already empty), at the moment this method is initially invoked or then subsequently when the listener is returning will not stop the asynchronous operation; the listener is guaranteed to be called back again at the latest as soon as all other events pending at the time of notification have been dispatched.

Only one write operation (synchronous or asynchronous) can be going on at any time.
Note therefore that while empty output buffer conditions (UARTEvent.OUTPUT_BUFFER_EMPTY) may be notified to the registered UARTEventListener independently from the invocation of the provided OutputRoundListener attempting to call the write method from within the registered UARTEventListener will result in an exception.

Parameters:

src1 - the first buffer for the data to be written.

src2 - the second buffer for the data to be written.

listener - the OutputRoundListener instance to be notified when all the data remaining in the working buffer has been written.

Throws:

java.lang.NullPointerException - If src1, src2 or listener is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.lang.IllegalStateException - if another synchronous or asynchronous output operation is already active.

java.io.IOException - if some other I/O error occurs such as the device is not writable.

stopWriting

void stopWriting()
                 throws java.io.IOException,
                        UnavailableDeviceException,
                        ClosedDeviceException

Stops (cancels) the currently active writing session.

This method return silently if no writing session is currently active.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

startReading

void startReading(java.nio.ByteBuffer dst,
                InputRoundListener<UART,java.nio.ByteBuffer> listener)
                  throws java.io.IOException,
                         UnavailableDeviceException,
                         ClosedDeviceException

Starts asynchronous reading in successive rounds - reading data into the provided buffer. The provided InputRoundListener is cyclicly notified when the provided buffer has been filled with input data. Reading into the buffer and notification will only resume once the event has been handled. Reading and notification will immediately start and will repeat until it is stopped by a call to stopReading.

r bytes will be read from this UART, where r is the number of bytes remaining in the buffer (possibly 0), that is, dst.remaining(), at the moment this method is initially invoked and then subsequently when the listener is returning.

Suppose that a byte sequence of length n is read, where 0 <= n <= r. This byte sequence will be transferred into the buffer so that the first byte in the sequence is at index p and the last byte is at index p + n - 1, where p is the buffer's position at the moment this method is initially invoked and then subsequently when the listener is returning. Upon invocation of the listener for fetching more data to write the buffer's position will be equal to p + n; its limit will not have changed.
The buffer's position upon stopping this asynchronous operation by a call to stopReading is not predictable unless called from within the listener..

The data will be read according to the current baud rate as returned by getBaudRate. The baud rate and other configuration parameters can be changed by the provided InputRoundListener instance upon notification of each round.

Note that a buffer with 0 bytes remaining to be read (that is a buffer already full), at the moment this method is initially invoked or then subsequently when the listener is returning will not stop the asynchronous operation; the listener is guaranteed to be called back again at the latest as soon as all other events pending at the time of notification have been dispatched.

Interfering with the asynchronous operation by accessing and modifying the provided buffer concurrently may yield unpredictable results.

Only one read operation (synchronous or asynchronous) can be going on at any time.
Note therefore that while the availability of new input data (UARTEvent.INPUT_DATA_AVAILABLE) may be notified to the registered UARTEventListener independently from the invocation of the provided InputRoundListener attempting to call the read method from within the registered UARTEventListener will result in an exception.

Parameters:

dst - the buffer for the data to be read.

listener - the InputRoundListener instance to be notified when the all remaining space in the buffer has been filled with input data.

Throws:

java.lang.NullPointerException - If src or listener is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.lang.IllegalStateException - if another synchronous or asynchronous input operation is already active.

java.io.IOException - if some other I/O error occurs such as the device is not readable.

startReading

void startReading(java.nio.ByteBuffer dst1,
                java.nio.ByteBuffer dst2,
                InputRoundListener<UART,java.nio.ByteBuffer> listener)
                  throws java.io.IOException,
                         UnavailableDeviceException,
                         ClosedDeviceException

Starts asynchronous reading in successive rounds.

This method behaves identically to startReading(ByteBuffer, InputRoundListener) excepts that it uses double-buffering. Notification will happen when all the remaining space in the current working buffer (initially dst1) has been filled and reading will proceed with the alternate buffer (which will become the current working buffer). Reading will only be suspended if the previous event has not yet been handled.

Note that a buffer with 0 bytes remaining to be read (that is a buffer already full), at the moment this method is initially invoked or then subsequently when the listener is returning will not stop the asynchronous operation; the listener is guaranteed to be called back again at the latest as soon as all other events pending at the time of notification have been dispatched.

Only one read operation (synchronous or asynchronous) can be going on at any time.
Note therefore that while the availability of new input data (UARTEvent.INPUT_DATA_AVAILABLE) may be notified to the registered UARTEventListener independently from the invocation of the provided InputRoundListener attempting to call the read method from within the registered UARTEventListener will result in an exception.

Parameters:

dst1 - the first buffer for the data to be read.

dst2 - the second buffer for the data to be read.

listener - the InputRoundListener instance to be notified when all the space remaining in the working buffer has been filled with input data.

Throws:

java.lang.NullPointerException - If dst1, dst2 or listener is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.lang.IllegalStateException - if another synchronous or asynchronous input operation is already active.

java.io.IOException - if some other I/O error occurs such as the device is not readable.

stopReading

void stopReading()
                 throws java.io.IOException,
                        UnavailableDeviceException,
                        ClosedDeviceException

Stops (cancels) the currently active reading session.

This method return silently if no reading session is currently active.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

generateBreak

void generateBreak(int duration)
                   throws java.io.IOException,
                          UnavailableDeviceException,
                          ClosedDeviceException

Generates a break condition for the specified duration.

Parameters:

duration - duration of the break condition to generate.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested receive trigger level.

java.io.IOException - if some other I/O error occurs.

setReceiveTriggerLevel

void setReceiveTriggerLevel(int level)
                            throws java.io.IOException,
                                   UnavailableDeviceException,
                                   ClosedDeviceException

Sets the receive trigger level. The UARTEventListener instance registered for UARTEvent.INPUT_DATA_AVAILABLE events (if any) will get notified after the specified number of bytes have been received in the input buffer. If a synchronous read operation is on-going it may then immediately return with the number of bytes already read.

Parameters:

level - the trigger level, in bytes.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested receive trigger level.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

getReceiveTriggerLevel

int getReceiveTriggerLevel()
                           throws java.io.IOException,
                                  UnavailableDeviceException,
                                  ClosedDeviceException

Gets the current receive trigger level.

Returns:

the trigger level, in bytes or 0 if this feature is not supported.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

setReceiveTimeout

void setReceiveTimeout(int timeout)
                       throws java.io.IOException,
                              UnavailableDeviceException,
                              ClosedDeviceException

Sets the receive timeout. The UARTEventListener instance registered for UARTEvent.INPUT_DATA_AVAILABLE events (if any) will get notified if there is at least one byte in the input buffer and the specified timeout has elapsed. If a synchronous read operation is on-going it may then immediately return with the number of bytes already read.

Parameters:

timeout - the timeout, in milliseconds.

Throws:

java.lang.UnsupportedOperationException - if this UART cannot be configured with the requested receive timeout.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

getReceiveTimeout

int getReceiveTimeout()
                      throws java.io.IOException,
                             UnavailableDeviceException,
                             ClosedDeviceException

Gets the current receive timeout.

Returns:

the timeout, in milliseconds or 0 if this feature is not supported.

Throws:

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if some other I/O error occurs.

read

int read(java.nio.ByteBuffer dst)
         throws java.io.IOException,
                UnavailableDeviceException,
                ClosedDeviceException

Reads a sequence of bytes from this UART into the given buffer. The method will block until the requested number of bytes are read or the receive trigger level (if set) has been reached or the receive timeout (if set) has elapsed.

Note that the availability of new input data may be notified through an UARTEvent with ID UARTEvent.INPUT_DATA_AVAILABLE according to the receive trigger level or receive timeout (if set).

Specified by:

read in interface java.nio.channels.ReadableByteChannel

Parameters:

dst - The buffer into which bytes are to be transferred

Returns:

The number of bytes read into dst, possibly zero, or -1 if the device has reached end-of-stream

Throws:

java.lang.NullPointerException - If dst is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if an I/O error occurred such as the device is not readable.

See Also:

setReceiveTriggerLevel, setReceiveTimeout

write

int write(java.nio.ByteBuffer src)
          throws java.io.IOException,
                 UnavailableDeviceException,
                 ClosedDeviceException

Writes a sequence of bytes to this UART from the given buffer.

Note that an empty output buffer condition may be notified through an UARTEvent with ID UARTEvent.OUTPUT_BUFFER_EMPTY.

Specified by:

write in interface java.nio.channels.WritableByteChannel

Parameters:

src - The buffer from which bytes are to be retrieved

Returns:

The number of bytes written from src, possibly zero.

Throws:

java.lang.NullPointerException - If src is null.

UnavailableDeviceException - if this device is not currently available - such as it is locked by another application.

ClosedDeviceException - if the device has been closed.

java.io.IOException - if an I/O error occurred such as the device is not writable.