001package com.pi4j.wiringpi; 002 003/* 004 * #%L 005 * ********************************************************************** 006 * ORGANIZATION : Pi4J 007 * PROJECT : Pi4J :: Java Library (Core) 008 * FILENAME : I2C.java 009 * 010 * This file is part of the Pi4J project. More information about 011 * this project can be found here: https://www.pi4j.com/ 012 * ********************************************************************** 013 * %% 014 * Copyright (C) 2012 - 2019 Pi4J 015 * %% 016 * This program is free software: you can redistribute it and/or modify 017 * it under the terms of the GNU Lesser General Public License as 018 * published by the Free Software Foundation, either version 3 of the 019 * License, or (at your option) any later version. 020 * 021 * This program is distributed in the hope that it will be useful, 022 * but WITHOUT ANY WARRANTY; without even the implied warranty of 023 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 024 * GNU General Lesser Public License for more details. 025 * 026 * You should have received a copy of the GNU General Lesser Public 027 * License along with this program. If not, see 028 * <http://www.gnu.org/licenses/lgpl-3.0.html>. 029 * #L% 030 */ 031 032 033import com.pi4j.util.NativeLibraryLoader; 034 035/** 036 * <p> 037 * WiringPi includes a library which can make it easier to use the Raspberry Pi’s on-board I2C interface. 038 * </p> 039 * 040 * <p> 041 * Before you can use the I2C interface, you may need to use the gpio utility to load the I2C drivers into the kernel: 042 * > gpio load i2c 043 * 044 * If you need a baud rate other than the default 100Kbps, then you can supply this on the command-line: 045 * > gpio load i2c 1000 046 * 047 * will set the baud rate to 1000Kbps – ie. 1,000,000 bps. (K here is times 1000) * 048 * </p> 049 * 050 * <p> 051 * <blockquote> This library depends on the wiringPi native system library.</br> (developed by 052 * Gordon Henderson @ <a href="http://wiringpi.com/">http://wiringpi.com/</a>) 053 * </blockquote> 054 * </p> 055 * 056 * @see <a href="https://www.pi4j.com/">https://www.pi4j.com</a> 057 * @see <a 058 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 059 * @author Robert Savage (<a 060 * href="http://www.savagehomeautomation.com">http://www.savagehomeautomation.com</a>) 061 */ 062public class I2C { 063 064 public static int CHANNEL_0 = 0; 065 public static int CHANNEL_1 = 1; 066 067 // private constructor 068 private I2C() { 069 // forbid object construction 070 } 071 072 static { 073 // Load the platform library 074 NativeLibraryLoader.load("libpi4j.so"); 075 } 076 077 /** 078 * <p>wiringPiI2CSetup:</p> 079 * 080 * <p> 081 * This initialises the I2C system with your given device identifier. The ID is the I2C number of the device 082 * and you can use the i2cdetect program to find this out. wiringPiI2CSetup() will work out which revision 083 * Raspberry Pi you have and open the appropriate device in /dev. 084 * </p> 085 * 086 * <p> 087 * The return value is the standard Linux filehandle, or -1 if any error – in which case, you can consult 088 * errno as usual. 089 * </p> 090 * 091 * <p> 092 * E.g. the popular MCP23017 GPIO expander is usually device Id 0×20, so this is the number you would pass 093 * into wiringPiI2CSetup(). 094 * </p> 095 * 096 * @see <a 097 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 098 * 099 * @param devid I2C device id 100 * @return return -1 on error; else returns Linux file handle 101 */ 102 public static native int wiringPiI2CSetup(int devid); 103 104 /** 105 * <p>wiringPiI2CRead:</p> 106 * 107 * <p> 108 * Simple I2C device read. Some devices present data when you read them without having to do any register transactions. 109 * </p> 110 * 111 * @see <a 112 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 113 * 114 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 115 * @return return -1 on error; else data read from I2C device 116 */ 117 public static native int wiringPiI2CRead(int fd); 118 119 /** 120 * <p>wiringPiI2CWrite:</p> 121 * 122 * <p> 123 * Simple I2C device write. Some devices accept data this way without needing to access any internal registers. 124 * </p> 125 * 126 * @see <a 127 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 128 * 129 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 130 * @param data data to write 131 * @return return -1 on error 132 */ 133 public static native int wiringPiI2CWrite(int fd, int data); 134 135 /** 136 * <p>wiringPiI2CWriteReg8:</p> 137 * 138 * <p> 139 * I2C device write. Write an 8-bit data value into the device register indicated. 140 * </p> 141 * 142 * @see <a 143 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 144 * 145 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 146 * @param reg I2C device register address 147 * @param data data byte to write (8 bits/1 byte) 148 * @return return -1 on error 149 */ 150 public static native int wiringPiI2CWriteReg8(int fd, int reg, int data); 151 152 /** 153 * <p>wiringPiI2CWriteReg16:</p> 154 * 155 * <p> 156 * I2C device write. Write a 16-bit data value into the device register indicated. 157 * </p> 158 * 159 * @see <a 160 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 161 * 162 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 163 * @param reg I2C device register address 164 * @param data data bytes to write (16 bits/2 bytes) 165 * @return return -1 on error 166 */ 167 public static native int wiringPiI2CWriteReg16(int fd, int reg, int data); 168 169 /** 170 * <p>wiringPiI2CReadReg8:</p> 171 * 172 * <p> 173 * I2C device read. Read an 8-bit (1 byte) data value from the device register indicated. 174 * </p> 175 * 176 * @see <a 177 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 178 * 179 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 180 * @param reg I2C device register address 181 * @return return -1 on error; else returns 8-bit value read from I2C device register 182 */ 183 public static native int wiringPiI2CReadReg8(int fd, int reg); 184 185 /** 186 * <p>wiringPiI2CReadReg16:</p> 187 * 188 * <p> 189 * I2C device read. Read a 16-bit (2 bytes) data value from the device register indicated. 190 * </p> 191 * 192 * @see <a 193 * href="http://wiringpi.com/reference/i2c-library/">http://wiringpi.com/reference/i2c-library</a> 194 * 195 * @param fd Linux file handle obtained from call to wiringPiI2CSetup 196 * @param reg I2C device register address 197 * @return return -1 on error; else returns 16-bit value read from I2C device register 198 */ 199 public static native int wiringPiI2CReadReg16(int fd, int reg); 200}