Package io.helins.linux.i2c

Class SMBus

java.lang.Object

io.helins.linux.i2c.SMBus

public class SMBus
extends Object

SMBus is more or less a subset of I2C and has its own standard.

As such, the Linux kernel provides utilities for executing SMBus operations on an I2C bus.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SMBus.Block	Class representing a block of bytes for SMBus operations.

Method Summary

Modifier and Type	Method	Description
int	blockProcessCall(int command, SMBus.Block block)	SMBus RPC-like operation, writing several bytes after specifying a command and then reading several bytes as an answer.
int	blockProcessCall(int command, SMBus.Block blockWrite, SMBus.Block blockRead)	SMBus RPC-like operation, writing several bytes after specifying a command and then reading several bytes as an answer.
int	processCall(int command, int word)	SMBus RPC-like operation, writing a short after specifying a command and then reading the answer.
void	quick(boolean isWrite)	SMBus operation sending only the READ or WRITE bit, no data is carried.
int	readBlock(int command, SMBus.Block block)	SMBus operation reading several bytes after specifying a command.
int	readByte(int command)	SMBus operation reading a byte after specifying a command.
int	readByteDirectly()	SMBus operation reading a byte without a command.
void	readI2CBlock(int command, SMBus.Block block, int length)	SMBus-like operation reading several bytes after specifying a command where the length is part of the message.
int	readWord(int command)	SMBus operation reading a short after specifying a command.
void	usePEC(boolean usePEC)	Enables or disables packet error checking for SMBus commands.
void	writeBlock(int command, SMBus.Block block)	SMBus operation writing several bytes after specifying a command.
void	writeByte(int command, int b)	SMBus operation writing a byte after specifying a command.
void	writeByteDirectly(int b)	SMBus operation writing a byte without a command.
void	writeI2CBlock(int command, SMBus.Block block)	SMBus-like operation writing several bytes after specifying a command where the length is part of the message.
void	writeWord(int command, int word)	SMBus operation writing a short after specifying a command.

Methods inherited from class java.lang.Object

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

Method Detail

usePEC

public void usePEC(boolean usePEC)
            throws IOException

Enables or disables packet error checking for SMBus commands.

Is ignored unless the underlying driver provides this functionality.

Slave devices do not necessarely support this feature either.

Parameters:

usePEC - Should PEC be enabled ?

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

quick

public void quick(boolean isWrite)
           throws IOException

SMBus operation sending only the READ or WRITE bit, no data is carried.

Parameters:

isWrite - True if the WRITE bit must be set.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

readByteDirectly

public int readByteDirectly()
                     throws IOException

SMBus operation reading a byte without a command.

Returns:

Unsigned byte received from the slave.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

readByte

public int readByte(int command)
             throws IOException

SMBus operation reading a byte after specifying a command.

Parameters:

command - AKA "register".

Returns:

Unsigned byte received from the slave.

Throws:

IllegalStateException - When thelbus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

readWord

public int readWord(int command)
             throws IOException

SMBus operation reading a short after specifying a command.

Parameters:

command - AKA "register".

Returns:

Unsigned short received from the slave.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

readBlock

public int readBlock(int command,
                     SMBus.Block block)
              throws IOException

SMBus operation reading several bytes after specifying a command.

Parameters:

command - AKA "register".

block - Block of bytes the answer will be written to.

Returns:

Number of bytes read.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

readI2CBlock

public void readI2CBlock(int command,
                         SMBus.Block block,
                         int length)
                  throws IOException

SMBus-like operation reading several bytes after specifying a command where the length is part of the message.

This operation is not in the SMBus standard but is often supported nonetheless.

Parameters:

command - AKA "register".

block - Block of bytes the answer will be written to.

length - How many bytes should be read.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

writeByteDirectly

public void writeByteDirectly(int b)
                       throws IOException

SMBus operation writing a byte without a command.

Parameters:

b - Unsigned byte that needs to be sent.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

writeByte

public void writeByte(int command,
                      int b)
               throws IOException

SMBus operation writing a byte after specifying a command.

Parameters:

command - AKA "register".

b - Unsigned byte that needs to be sent.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

writeWord

public void writeWord(int command,
                      int word)
               throws IOException

SMBus operation writing a short after specifying a command.

Parameters:

command - AKA "register".

word - Unsigned short that needs to be sent.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

writeBlock

public void writeBlock(int command,
                       SMBus.Block block)
                throws IOException

SMBus operation writing several bytes after specifying a command.

After the command byte, the master also sends a byte count, how many bytes will be written.

Parameters:

command - AKA "register".

block - Block of bytes to write.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

writeI2CBlock

public void writeI2CBlock(int command,
                          SMBus.Block block)
                   throws IOException

SMBus-like operation writing several bytes after specifying a command where the length is part of the message.

This operation is not in the SMBus standard but is often supported nonetheless.

Unlike writeBlock, this operation does not send a byte count after the command.

Parameters:

command - AKA "register".

block - Block of bytes to write.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

processCall

public int processCall(int command,
                       int word)
                throws IOException

SMBus RPC-like operation, writing a short after specifying a command and then reading the answer.

Parameters:

command - AKA "register".

word - Unsigned short to be sent.

Returns:

Unsigned short given back by the slave.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

blockProcessCall

public int blockProcessCall(int command,
                            SMBus.Block block)
                     throws IOException

SMBus RPC-like operation, writing several bytes after specifying a command and then reading several bytes as an answer.

Parameters:

command - AKA "register".

block - Block of bytes to write, also where the answer will be written to.

Returns:

Number of bytes read.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.

blockProcessCall

public int blockProcessCall(int command,
                            SMBus.Block blockWrite,
                            SMBus.Block blockRead)
                     throws IOException

SMBus RPC-like operation, writing several bytes after specifying a command and then reading several bytes as an answer.

Parameters:

command - AKA "register".

blockWrite - Block of bytes to write.

blockRead - Block of bytes the answer will be written to (can be the same as blockWrite if it can be overwritten).

Returns:

Number of bytes read.

Throws:

IllegalStateException - When the underlying I2C bus has been closed.

IOException - When the bus is not a proper I2C bus or an unplanned error occured.