Class LinuxFsI2C

java.lang.Object

com.pi4j.common.IdentityBase

com.pi4j.io.IOBase<I2C,I2CConfig,I2CProvider>

com.pi4j.io.i2c.I2CBase<LinuxFsI2CBus>

com.pi4j.plugin.linuxfs.provider.i2c.LinuxFsI2C

All Implemented Interfaces:

Describable, Identity, Lifecycle, Extension, I2C, I2CRegisterDataReader, I2CRegisterDataReaderWriter, I2CRegisterDataWriter, IO<I2C,I2CConfig,I2CProvider>, IODataReader, IODataWriter, AutoCloseable, Readable

public class LinuxFsI2C
extends I2CBase<LinuxFsI2CBus>
implements I2C

PiGpioI2C class.

Version:

$Id: $Id

Author:

Robert Savage (http://www.savagehomeautomation.com)

Field Summary

Fields inherited from class com.pi4j.io.i2c.I2CBase

isOpen

Fields inherited from class com.pi4j.io.IOBase

config, provider

Fields inherited from class com.pi4j.common.IdentityBase

description, id, logger, metadata, name

Constructor Summary

Constructors

Constructor	Description
LinuxFsI2C(LinuxFsI2CBus i2CBus, I2CProvider provider, I2CConfig config)	Constructor for PiGpioI2C.

Method Summary

Modifier and Type	Method	Description
int	read()
int	read(byte[] buffer, int offset, int length)
int	readRegister(byte[] register, byte[] buffer, int offset, int length)
int	readRegister(int register)
int	readRegister(int register, byte[] buffer, int offset, int length)
int	write(byte b)
int	write(byte[] data, int offset, int length)
int	writeReadRegisterWord(int register, int word)
int	writeRegister(byte[] register, byte[] data, int offset, int length)
int	writeRegister(int register, byte b)
int	writeRegister(int register, byte[] data, int offset, int length)

Methods inherited from class com.pi4j.io.i2c.I2CBase

close, execute, getRegister, isOpen, shutdown

Methods inherited from class com.pi4j.io.IOBase

config, context, describe, description, initialize, name, provider

Methods inherited from class com.pi4j.common.IdentityBase

description, id, metadata, name

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.pi4j.io.i2c.I2C

bus, close, device, execute, getBus, getDevice, getRegister, isOpen, register, writeRead, writeRead

Methods inherited from interface com.pi4j.io.i2c.I2CRegisterDataReader

readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegister, readRegisterByte, readRegisterByteBuffer, readRegisterByteBuffer, readRegisterCharArray, readRegisterCharArray, readRegisterCharArray, readRegisterCharArray, readRegisterCharBuffer, readRegisterCharBuffer, readRegisterCharBuffer, readRegisterCharBuffer, readRegisterNBytes, readRegisterNBytes, readRegisterString, readRegisterString, readRegisterString, readRegisterString, readRegisterWord

Methods inherited from interface com.pi4j.io.i2c.I2CRegisterDataWriter

write, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegister, writeRegisterWord

Methods inherited from interface com.pi4j.common.Identity

description, getDescription, getId, getMetadata, getName, id, metadata, name

Methods inherited from interface com.pi4j.io.IO

config, description, name, provider, type

Methods inherited from interface com.pi4j.io.IODataReader

getInputStream, in, read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, read, readByte, readByteBuffer, readByteBuffer, readCharArray, readCharArray, readCharArray, readCharArray, readCharBuffer, readCharBuffer, readCharBuffer, readCharBuffer, readNBytes, readNBytes, readString, readString, readString, readString

Methods inherited from interface com.pi4j.io.IODataWriter

getOutputStream, out, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write, write

Methods inherited from interface com.pi4j.common.Lifecycle

initialize, shutdown

Constructor Details

LinuxFsI2C

public LinuxFsI2C(LinuxFsI2CBus i2CBus,
 I2CProvider provider,
 I2CConfig config)

Constructor for PiGpioI2C.

Parameters:

i2CBus -

provider - a I2CProvider object.

config - a I2CConfig object.

Method Details

write

public int write(byte b)

Specified by:

write in interface IODataWriter

write

public int write(byte[] data,
 int offset,
 int length)

Specified by:

write in interface IODataWriter

read

public int read()

Specified by:

read in interface IODataReader

read

public int read(byte[] buffer,
 int offset,
 int length)

Specified by:

read in interface IODataReader

writeRegister

public int writeRegister(int register,
 byte b)

Specified by:

writeRegister in interface I2CRegisterDataWriter

writeRegister

public int writeRegister(int register,
 byte[] data,
 int offset,
 int length)

Specified by:

writeRegister in interface I2CRegisterDataWriter

writeRegister

public int writeRegister(byte[] register,
 byte[] data,
 int offset,
 int length)

Specified by:

writeRegister in interface I2CRegisterDataWriter

readRegister

public int readRegister(int register)

Specified by:

readRegister in interface I2CRegisterDataReader

readRegister

public int readRegister(int register,
 byte[] buffer,
 int offset,
 int length)

Specified by:

readRegister in interface I2CRegisterDataReader

readRegister

public int readRegister(byte[] register,
 byte[] buffer,
 int offset,
 int length)

This function uses the IOCTL interface to the LinuxFS. This is required so the I2C transaction uses an I2C RESTART. The following details explain creating the ByteBuffers used to create the 'C" structures for the IOCTL.

i2c_msg: The space *buf will be used to set a pointer to the data buffer. This pointer must be aligned to the machines 4 or 8 byte alignment.

This alignment is accomplished when the pointer is 'put' into the ByteBuffer

• struct i2c_msg {
• __u16 addr;
• __u16 flags;
• __u16 len;
• __u8 *buf; wordSize
• u8 buffer
• };

The ioctl command is I2CConstants.I2C_RDWR, this command requires two i2c_msg entries.

The following describes the ByteBuffer, ioctlData, contents:

• two byte address entry one
• two byte len entry one
• Possible padding for alignment
• word size area for pointer to write data buffer
• two byte address entry two
• two byte flags entry two
• two byte len entry two
• Possible padding for alignment
• word size area for pointer to read data buffer
• Bytes required to contain write buffer contents
• Bytes required to contain read data buffer

There is a second byte buffer, offsets, this specifies the ByteBuffer offset of any pointer paired with the ByteBuffer offset of the data pointed to.

This ByteBuffer contents

• ByteBuffer position start of pointer to write data buffer
• ByteBuffer position start of write buffer contents
• ByteBuffer position start of pointer to read data buffer
• ByteBuffer position start of read buffer contents

Specified by:

readRegister in interface I2CRegisterDataReader

writeReadRegisterWord

public int writeReadRegisterWord(int register,
 int word)

Specified by:

writeReadRegisterWord in interface I2CRegisterDataReaderWriter