com.pi4j.io.i2c.impl

Class I2CBusImpl

java.lang.Object

com.pi4j.io.i2c.impl.I2CBusImpl

All Implemented Interfaces:

I2CBus

public class I2CBusImpl
extends Object
implements I2CBus

This is implementation of i2c bus. This class keeps underlying linux file descriptor of particular bus. As all reads and writes from/to i2c bus are blocked I/Os current implementation uses only one file per bus for all devices. Device implementations use this class file handle. Hint: For concurrency-locking the methods lock() and unlock() are provided. This requires that there is exactly one I2CBus-instance per bus-number what is guaranteed by the I2CFactory class. The locking is done by I2CDeviceImpl by using those methods. The reason for this is to enable other locking-strategies than the simple "lock before and release after access"-strategy.

Author:

Daniel Sendula, refactored by RasPelikan

Field Summary

Fields

Modifier and Type	Field and Description
protected int	busNumber Used to identifiy the i2c bus within Pi4J
protected LinuxFile	file File handle for this i2c bus
protected String	filename File name of this i2c bus
protected int	lastAddress
protected long	lockAquireTimeout
protected TimeUnit	lockAquireTimeoutUnit

Fields inherited from interface com.pi4j.io.i2c.I2CBus

BUS_0, BUS_1, BUS_10, BUS_11, BUS_12, BUS_13, BUS_14, BUS_15, BUS_16, BUS_17, BUS_2, BUS_3, BUS_4, BUS_5, BUS_6, BUS_7, BUS_8, BUS_9

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	I2CBusImpl(int busNumber, String fileName, long lockAquireTimeout, TimeUnit lockAquireTimeoutUnit) Constructor of i2c bus implementation.

Method Summary

Modifier and Type	Method and Description
void	close() Closes this i2c bus.
int	getBusNumber()
I2CDevice	getDevice(int address) Returns i2c device implementation (I2CDeviceImpl).
void	ioctl(I2CDevice device, long command, ByteBuffer values, IntBuffer offsets)
void	ioctl(I2CDevice device, long command, int value)
protected void	open() Opens the bus.
int	readByte(I2CDevice device, int localAddress)
int	readByteDirect(I2CDevice device)
int	readBytes(I2CDevice device, int localAddress, int size, int offset, byte[] buffer)
int	readBytesDirect(I2CDevice device, int size, int offset, byte[] buffer)
<T> T	runBusLockedDeviceAction(I2CDevice device, Callable<T> action) Selects a device on the bus for an action, and locks parallel access around file descriptor operations.
protected void	selectBusSlave(I2CDevice device) Selects the slave device if not already selected on this bus.
protected void	testForProperOperationConditions(I2CDevice device)
String	toString()
int	writeAndReadBytesDirect(I2CDevice device, int writeSize, int writeOffset, byte[] writeBuffer, int readSize, int readOffset, byte[] readBuffer)
void	writeByte(I2CDevice device, int localAddress, byte data)
void	writeByteDirect(I2CDevice device, byte data)
void	writeBytes(I2CDevice device, int localAddress, int size, int offset, byte[] buffer)
void	writeBytesDirect(I2CDevice device, int size, int offset, byte[] buffer)

Methods inherited from class java.lang.Object

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

Field Detail

file

protected LinuxFile file

File handle for this i2c bus

lastAddress

protected int lastAddress

filename

protected String filename

File name of this i2c bus

busNumber

protected int busNumber

Used to identifiy the i2c bus within Pi4J

lockAquireTimeout

protected long lockAquireTimeout

lockAquireTimeoutUnit

protected TimeUnit lockAquireTimeoutUnit

Constructor Detail

I2CBusImpl

protected I2CBusImpl(int busNumber,
                     String fileName,
                     long lockAquireTimeout,
                     TimeUnit lockAquireTimeoutUnit)

Constructor of i2c bus implementation.

Parameters:

busNumber - used to identifiy the i2c bus within Pi4J

Throws:

IOException - thrown in case that file cannot be opened

Method Detail

getDevice

public I2CDevice getDevice(int address)
                    throws IOException

Returns i2c device implementation (I2CDeviceImpl).

Specified by:

getDevice in interface I2CBus

Parameters:

address - address of i2c device

Returns:

implementation of i2c device with given address

Throws:

IOException - never in this implementation

open

protected void open()
             throws IOException

Opens the bus.

Throws:

IOException - thrown in case there are problems opening the i2c bus.

close

public void close()
           throws IOException

Closes this i2c bus. Can be used in a thread safe way during bus operations.

Specified by:

close in interface I2CBus

Throws:

IOException - never in this implementation

readByteDirect

public int readByteDirect(I2CDevice device)
                   throws IOException

Throws:

IOException

readBytesDirect

public int readBytesDirect(I2CDevice device,
                           int size,
                           int offset,
                           byte[] buffer)
                    throws IOException

Throws:

IOException

readByte

public int readByte(I2CDevice device,
                    int localAddress)
             throws IOException

Throws:

IOException

readBytes

public int readBytes(I2CDevice device,
                     int localAddress,
                     int size,
                     int offset,
                     byte[] buffer)
              throws IOException

Throws:

IOException

writeByteDirect

public void writeByteDirect(I2CDevice device,
                            byte data)
                     throws IOException

Throws:

IOException

writeBytesDirect

public void writeBytesDirect(I2CDevice device,
                             int size,
                             int offset,
                             byte[] buffer)
                      throws IOException

Throws:

IOException

writeByte

public void writeByte(I2CDevice device,
                      int localAddress,
                      byte data)
               throws IOException

Throws:

IOException

writeBytes

public void writeBytes(I2CDevice device,
                       int localAddress,
                       int size,
                       int offset,
                       byte[] buffer)
                throws IOException

Throws:

IOException

writeAndReadBytesDirect

public int writeAndReadBytesDirect(I2CDevice device,
                                   int writeSize,
                                   int writeOffset,
                                   byte[] writeBuffer,
                                   int readSize,
                                   int readOffset,
                                   byte[] readBuffer)
                            throws IOException

Throws:

IOException

ioctl

public void ioctl(I2CDevice device,
                  long command,
                  int value)
           throws IOException

Throws:

IOException

ioctl

public void ioctl(I2CDevice device,
                  long command,
                  ByteBuffer values,
                  IntBuffer offsets)
           throws IOException

Throws:

IOException

runBusLockedDeviceAction

public <T> T runBusLockedDeviceAction(I2CDevice device,
                                      Callable<T> action)
                               throws IOException

Selects a device on the bus for an action, and locks parallel access around file descriptor operations. Multiple bus instances may be used in parallel, but a single bus instance must limit parallel access.

The timeout used for the acquisition of the lock may be defined on getting the I2CBus from I2CFactory.

The 'run'-method of 'action' may throw an 'IOExceptionWrapperException' to wrap IOExceptions. The wrapped IOException is unwrapped by this method and rethrown as IOException.

Type Parameters:

T - The result-type of the method

Parameters:

device - Device to be selected on the bus

action - The action to be run

Throws:

RuntimeException - thrown by the custom code

IOException - see method description above

See Also:

I2CFactory.getInstance(int, long, java.util.concurrent.TimeUnit)

selectBusSlave

protected void selectBusSlave(I2CDevice device)
                       throws IOException

Selects the slave device if not already selected on this bus. Uses SharedSecrets to get the POSIX file descriptor, and runs the required ioctl's via JNI.

Parameters:

device - Device to select

Throws:

IOException

testForProperOperationConditions

protected void testForProperOperationConditions(I2CDevice device)
                                         throws IOException

Throws:

IOException

getBusNumber

public int getBusNumber()

Specified by:

getBusNumber in interface I2CBus

Returns:

The bus' number

toString

public String toString()

Overrides:

toString in class Object