com.pi4j.wiringpi.I2C Maven / Gradle / Ivy

package com.pi4j.wiringpi;

/*
 * #%L
 * **********************************************************************
ORGANIZATION  :  Pi4J
PROJECT       :  Pi4J :: Java Library (Core)
FILENAME      :  I2C.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 - 2018 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.util.NativeLibraryLoader;

/**
 * 
 * WiringPi includes a library which can make it easier to use the Raspberry Pi�s on-board I2C interface.
 * 
 *
 * 
 * Before you can use the I2C interface, you may need to use the gpio utility to load the I2C drivers into the kernel:
 *  > gpio load i2c
 *
 * If you need a baud rate other than the default 100Kbps, then you can supply this on the command-line:
 *  > gpio load i2c 1000
 *
 * will set the baud rate to 1000Kbps � ie. 1,000,000 bps. (K here is times 1000) *
 * 
 *
 * 
 * 
 This library depends on the wiringPi native system library.
 (developed by
 * Gordon Henderson @ http://wiringpi.com/)
 * 
 * 
 *
 * @see http://www.pi4j.com
 * @see http://wiringpi.com/reference/i2c-library
 * @author Robert Savage (http://www.savagehomeautomation.com)
 */
public class I2C {

    public static int CHANNEL_0 = 0;
    public static int CHANNEL_1 = 1;

    // private constructor
    private I2C()  {
        // forbid object construction
    }

    static {
        // Load the platform library
        NativeLibraryLoader.load("libpi4j.so");
    }

    /**
     * wiringPiI2CSetup:
     *
     * 
     * This initialises the I2C system with your given device identifier. The ID is the I2C number of the device
     * and you can use the i2cdetect program to find this out. wiringPiI2CSetup() will work out which revision
     * Raspberry Pi you have and open the appropriate device in /dev.
     * 
     *
     * 
     * The return value is the standard Linux filehandle, or -1 if any error � in which case, you can consult
     * errno as usual.
     * 
     *
     * 
     * E.g. the popular MCP23017 GPIO expander is usually device Id 0�20, so this is the number you would pass
     * into wiringPiI2CSetup().
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param devid I2C device id
     * @return return -1 on error; else returns Linux file handle
     */
    public static native int wiringPiI2CSetup(int devid);

    /**
     * wiringPiI2CRead:
     *
     * 
     * Simple I2C device read. Some devices present data when you read them without having to do any register transactions.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @return return -1 on error; else data read from I2C device
     */
    public static native int wiringPiI2CRead(int fd);

    /**
     * wiringPiI2CWrite:
     *
     * 
     * Simple I2C device write. Some devices accept data this way without needing to access any internal registers.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @param data data to write
     * @return return -1 on error
     */
    public static native int wiringPiI2CWrite(int fd, int data);

    /**
     * wiringPiI2CWriteReg8:
     *
     * 
     * I2C device write. Write an 8-bit data value into the device register indicated.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @param reg I2C device register address
     * @param data data byte to write (8 bits/1 byte)
     * @return return -1 on error
     */
    public static native int wiringPiI2CWriteReg8(int fd, int reg, int data);

    /**
     * wiringPiI2CWriteReg16:
     *
     * 
     * I2C device write. Write a 16-bit data value into the device register indicated.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @param reg I2C device register address
     * @param data data bytes to write (16 bits/2 bytes)
     * @return return -1 on error
     */
    public static native int wiringPiI2CWriteReg16(int fd, int reg, int data);

    /**
     * wiringPiI2CReadReg8:
     *
     * 
     * I2C device read. Read an 8-bit (1 byte) data value from the device register indicated.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @param reg I2C device register address
     * @return return -1 on error; else returns 8-bit value read from I2C device register
     */
    public static native int wiringPiI2CReadReg8(int fd, int reg);

    /**
     * wiringPiI2CReadReg16:
     *
     * 
     * I2C device read. Read a 16-bit (2 bytes) data value from the device register indicated.
     * 
     *
     * @see http://wiringpi.com/reference/i2c-library
     *
     * @param fd Linux file handle obtained from call to wiringPiI2CSetup
     * @param reg I2C device register address
     * @return return -1 on error; else returns 16-bit value read from I2C device register
     */
    public static native int wiringPiI2CReadReg16(int fd, int reg);
}