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Pi4J Java API & Runtime Library
package com.pi4j.io.i2c.impl;
/*
* #%L
* **********************************************************************
* ORGANIZATION : Pi4J
* PROJECT : Pi4J :: Java Library (Core)
* FILENAME : I2CDeviceImpl.java
*
* This file is part of the Pi4J project. More information about
* this project can be found here: http://www.pi4j.com/
* **********************************************************************
* %%
* Copyright (C) 2012 - 2015 Pi4J
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import com.pi4j.io.i2c.I2CBus;
import com.pi4j.io.i2c.I2CDevice;
import com.pi4j.jni.I2C;
import java.io.IOException;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* Implementation of i2c device. This class only holds reference to i2c bus (so it can use its handle) and
* device address.
*
* @author Daniel Sendula
*
*/
public class I2CDeviceImpl implements I2CDevice {
/** Reference to i2c bus */
private I2CBus bus;
/** I2c device address */
private int deviceAddress;
private final static Lock lock = new ReentrantLock( true );
/**
* Constructor.
*
* @param bus i2c bus
* @param address i2c device address
*/
public I2CDeviceImpl(I2CBus bus, int address) {
this.bus = bus;
this.deviceAddress = address;
}
/**
* This method writes one byte to i2c device.
*
* @param data byte to be written
*
* @throws IOException thrown in case byte cannot be written to the i2c device or i2c bus
*/
@Override
public void write(byte data) throws IOException {
lock.lock();
try {
int ret = I2C.i2cWriteByteDirect(bus.getFileDescriptor(), deviceAddress, data);
if (ret < 0) {
throw new IOException("Error writing to " + makeDescription() + ". Got " + ret + ".");
}
} finally {
lock.unlock();
}
}
/**
* This method writes several bytes to the i2c device from given buffer at given offset.
*
* @param buffer buffer of data to be written to the i2c device in one go
* @param offset offset in buffer
* @param size number of bytes to be written
*
* @throws IOException thrown in case byte cannot be written to the i2c device or i2c bus
*/
@Override
public void write(byte[] buffer, int offset, int size) throws IOException {
lock.lock();
try {
int ret = I2C.i2cWriteBytesDirect(bus.getFileDescriptor(), deviceAddress, size, offset, buffer);
if (ret < 0) {
throw new IOException("Error writing to " + makeDescription() + ". Got " + ret + ".");
}
} finally {
lock.unlock();
}
}
/**
* This method writes one byte to i2c device.
*
* @param address local address in the i2c device
* @param data byte to be written
*
* @throws IOException thrown in case byte cannot be written to the i2c device or i2c bus
*/
@Override
public void write(int address, byte data) throws IOException {
lock.lock();
try {
int ret = I2C.i2cWriteByte(bus.getFileDescriptor(), deviceAddress, address, data);
if (ret < 0) {
throw new IOException("Error writing to " + makeDescription(address) + ". Got " + ret + ".");
}
} finally {
lock.unlock();
}
}
/**
* This method writes several bytes to the i2c device from given buffer at given offset.
*
* @param address local address in the i2c device
* @param buffer buffer of data to be written to the i2c device in one go
* @param offset offset in buffer
* @param size number of bytes to be written
*
* @throws IOException thrown in case byte cannot be written to the i2c device or i2c bus
*/
@Override
public void write(int address, byte[] buffer, int offset, int size) throws IOException {
lock.lock();
try {
int ret = I2C.i2cWriteBytes(bus.getFileDescriptor(), deviceAddress, address, size, offset, buffer);
if (ret < 0) {
throw new IOException("Error writing to " + makeDescription(address) + ". Got " + ret + ".");
}
} finally {
lock.unlock();
}
}
/**
* This method reads one byte from the i2c device.
* Result is between 0 and 255 if read operation was successful, else a negative number for an error.
*
* @return byte value read: positive number (or zero) to 255 if read was successful. Negative number if reading failed.
*
* @throws IOException thrown in case byte cannot be read from the i2c device or i2c bus
*/
@Override
public int read() throws IOException {
lock.lock();
try {
int ret = I2C.i2cReadByteDirect(bus.getFileDescriptor(), deviceAddress);
if (ret < 0) {
throw new IOException("Error reading from " + makeDescription() + ". Got " + ret + ".");
}
return ret;
} finally {
lock.unlock();
}
}
/**
* This method reads bytes from the i2c device to given buffer at asked offset.
*
* Note: Current implementation calls {@link #read(int)}. That means for each read byte
* i2c bus will send (next) address to i2c device.
*
*
* @param buffer buffer of data to be read from the i2c device in one go
* @param offset offset in buffer
* @param size number of bytes to be read
*
* @return number of bytes read
*
* @throws IOException thrown in case byte cannot be read from the i2c device or i2c bus
*/
@Override
public int read(byte[] buffer, int offset, int size) throws IOException {
lock.lock();
try {
// It doesn't work for some reason.
int ret = I2C.i2cReadBytesDirect(bus.getFileDescriptor(), deviceAddress, size, offset, buffer);
if (ret < 0) {
throw new IOException("Error reading from " + makeDescription() + ". Got " + ret + ".");
}
return ret;
} finally {
lock.unlock();
}
}
/**
* This method reads one byte from the i2c device.
* Result is between 0 and 255 if read operation was successful, else a negative number for an error.
*
* @param address local address in the i2c device
* @return byte value read: positive number (or zero) to 255 if read was successful. Negative number if reading failed.
*
* @throws IOException thrown in case byte cannot be read from the i2c device or i2c bus
*/
@Override
public int read(int address) throws IOException {
lock.lock();
try {
int ret = I2C.i2cReadByte(bus.getFileDescriptor(), deviceAddress, address);
if (ret < 0) {
throw new IOException("Error reading from " + makeDescription(address) + ". Got " + ret + ".");
}
return ret;
} finally {
lock.unlock();
}
}
/**
* This method reads bytes from the i2c device to given buffer at asked offset.
*
* Note: Current implementation calls {@link #read(int)}. That means for each read byte
* i2c bus will send (next) address to i2c device.
*
*
* @param address local address in the i2c device
* @param buffer buffer of data to be read from the i2c device in one go
* @param offset offset in buffer
* @param size number of bytes to be read
*
* @return number of bytes read
*
* @throws IOException thrown in case byte cannot be read from the i2c device or i2c bus
*/
@Override
public int read(int address, byte[] buffer, int offset, int size) throws IOException {
lock.lock();
try {
// It doesn't work for some reason.
int ret = I2C.i2cReadBytes(bus.getFileDescriptor(), deviceAddress, address, size, offset, buffer);
if (ret < 0) {
throw new IOException("Error reading from " + makeDescription(address) + ". Got " + ret + ".");
}
return ret;
} finally {
lock.unlock();
}
}
/**
* This method writes and reads bytes to/from the i2c device in a single method call
*
* @param writeBuffer buffer of data to be written to the i2c device in one go
* @param writeOffset offset in write buffer
* @param writeSize number of bytes to be written from buffer
* @param readBuffer buffer of data to be read from the i2c device in one go
* @param readOffset offset in read buffer
* @param readSize number of bytes to be read
*
* @return number of bytes read
*
* @throws IOException thrown in case byte cannot be read from the i2c device or i2c bus
*/
@Override
public int read(byte[] writeBuffer, int writeOffset, int writeSize, byte[] readBuffer, int readOffset, int readSize) throws IOException {
lock.lock();
try {
int ret = I2C.i2cWriteAndReadBytes(bus.getFileDescriptor(), deviceAddress, writeSize, writeOffset, writeBuffer, readSize, readOffset, readBuffer);
if (ret < 0) {
throw new IOException("Error reading from " + makeDescription() + ". Got " + ret + ".");
}
return ret;
} finally {
lock.unlock();
}
}
/**
* This helper method creates a string describing bus file name and device address (in hex).
*
* @return string with all details
*/
protected String makeDescription() {
return bus.getFileName() + " at address 0x" + Integer.toHexString(deviceAddress);
}
/**
* This helper method creates a string describing bus file name, device address (in hex)
* and local i2c address.
*
* @param address local address in i2c device
* @return string with all details
*/
protected String makeDescription(int address) {
return bus.getFileName() + " at address 0x" + Integer.toHexString(deviceAddress)
+ " to address 0x" + Integer.toHexString(address);
}
}
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