1 /* 2 * Author: Brendan Le Foll <brendan.le.foll@intel.com> 3 * Author: Thomas Ingleby <thomas.c.ingleby@intel.com> 4 * Copyright (c) 2014 Intel Corporation. 5 * Author: Petre Eftime <petre.p.eftime@intel.com> 6 * Copyright (c) 2015 Intel Corporation. 7 * 8 * Permission is hereby granted, free of charge, to any person obtaining 9 * a copy of this software and associated documentation files (the 10 * "Software"), to deal in the Software without restriction, including 11 * without limitation the rights to use, copy, modify, merge, publish, 12 * distribute, sublicense, and/or sell copies of the Software, and to 13 * permit persons to whom the Software is furnished to do so, subject to 14 * the following conditions: 15 * 16 * The above copyright notice and this permission notice shall be 17 * included in all copies or substantial portions of the Software. 18 * 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 21 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 23 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 24 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 25 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 26 */ 27 28 import mraa.I2c; 29 30 public class I2cCompass { 31 static { 32 try { 33 System.loadLibrary("mraajava"); 34 } catch (UnsatisfiedLinkError e) { 35 System.err.println( 36 "Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" + 37 e); 38 System.exit(1); 39 } 40 } 41 42 final static byte MAX_BUFFER_LENGTH = 6; 43 final static byte CONF_BUFFER_LENGTH = 2; 44 final static short HMC5883L_I2C_ADDR = 0x1E; 45 46 // configuration registers 47 final static byte HMC5883L_CONF_REG_A = 0x00; 48 final static byte HMC5883L_CONF_REG_B = 0x01; 49 50 // mode register 51 final static byte HMC5883L_MODE_REG = 0x02; 52 53 // data register 54 final static byte HMC5883L_X_MSB_REG = 0; 55 final static byte HMC5883L_X_LSB_REG = 1; 56 final static byte HMC5883L_Z_MSB_REG = 2; 57 final static byte HMC5883L_Z_LSB_REG = 3; 58 final static byte HMC5883L_Y_MSB_REG = 4; 59 final static byte HMC5883L_Y_LSB_REG = 5; 60 final static byte DATA_REG_SIZE = 6; 61 62 // status register 63 final static byte HMC5883L_STATUS_REG = 0x09; 64 65 // ID registers 66 final static byte HMC5883L_ID_A_REG = 0x0A; 67 final static byte HMC5883L_ID_B_REG = 0x0B; 68 final static byte HMC5883L_ID_C_REG = 0x0C; 69 70 final static byte HMC5883L_CONT_MODE = 0x00; 71 final static byte HMC5883L_DATA_REG = 0x03; 72 73 // scales 74 final static byte GA_0_88_REG = ((byte) (0x00 << 5)); 75 final static byte GA_1_3_REG = ((byte) (0x01 << 5)); 76 final static byte GA_1_9_REG = ((byte) (0x02 << 5)); 77 final static byte GA_2_5_REG = ((byte) (0x03 << 5)); 78 final static byte GA_4_0_REG = ((byte) (0x04 << 5)); 79 final static byte GA_4_7_REG = ((byte) (0x05 << 5)); 80 final static byte GA_5_6_REG = ((byte) (0x06 << 5)); 81 final static byte GA_8_1_REG = ((byte) (0x07 << 5)); 82 83 // digital resolutions 84 final static float SCALE_0_73_MG = 0.73f; 85 final static float SCALE_0_92_MG = 0.92f; 86 final static float SCALE_1_22_MG = 1.22f; 87 final static float SCALE_1_52_MG = 1.52f; 88 final static float SCALE_2_27_MG = 2.27f; 89 final static float SCALE_2_56_MG = 2.56f; 90 final static float SCALE_3_03_MG = 3.03f; 91 final static float SCALE_4_35_MG = 4.35f; 92 main(String[] args)93 public static void main(String[] args) throws InterruptedException { 94 float direction = 0; 95 int x, y, z; 96 byte[] rx_tx_buf = new byte[MAX_BUFFER_LENGTH]; 97 byte[] conf_buf = new byte[CONF_BUFFER_LENGTH]; 98 99 //! [Interesting] 100 I2c i2c = new I2c(0); 101 102 i2c.address(HMC5883L_I2C_ADDR); 103 conf_buf[0] = HMC5883L_CONF_REG_B; 104 conf_buf[1] = GA_1_3_REG; 105 i2c.write(conf_buf); 106 //! [Interesting] 107 108 i2c.address(HMC5883L_I2C_ADDR); 109 conf_buf[0] = HMC5883L_MODE_REG; 110 conf_buf[1] = HMC5883L_CONT_MODE; 111 i2c.write(conf_buf); 112 113 while (true) { 114 i2c.address(HMC5883L_I2C_ADDR); 115 i2c.writeByte(HMC5883L_DATA_REG); 116 117 i2c.address(HMC5883L_I2C_ADDR); 118 i2c.read(rx_tx_buf); 119 120 x = (rx_tx_buf[HMC5883L_X_MSB_REG] << 8) | rx_tx_buf[HMC5883L_X_LSB_REG]; 121 z = (rx_tx_buf[HMC5883L_Z_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Z_LSB_REG]; 122 y = (rx_tx_buf[HMC5883L_Y_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Y_LSB_REG]; 123 124 direction = (float) Math.atan2(y * SCALE_0_92_MG, x * SCALE_0_92_MG); 125 126 if (direction < 0) 127 direction += 2 * Math.PI; 128 129 System.out.println(String.format("Compass scaled data x : %f, y : %f, z : %f\n", x * SCALE_0_92_MG, y * SCALE_0_92_MG, 130 z * SCALE_0_92_MG)); 131 System.out.println(String.format("Heading : %f\n", direction * 180 / Math.PI)); 132 Thread.sleep(1000); 133 } 134 } 135 } 136