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/*
* Author: Brendan Le Foll <brendan.le.foll@intel.com>
* Author: Thomas Ingleby <thomas.c.ingleby@intel.com>
* Copyright (c) 2014 Intel Corporation.
* Author: Petre Eftime <petre.p.eftime@intel.com>
* Copyright (c) 2015 Intel Corporation.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
import mraa.I2c;
public class I2cCompass {
static {
try {
System.loadLibrary("mraajava");
} catch (UnsatisfiedLinkError e) {
System.err.println(
"Native code library failed to load. See the chapter on Dynamic Linking Problems in the SWIG Java documentation for help.\n" +
e);
System.exit(1);
}
}
final static byte MAX_BUFFER_LENGTH = 6;
final static byte CONF_BUFFER_LENGTH = 2;
final static short HMC5883L_I2C_ADDR = 0x1E;
// configuration registers
final static byte HMC5883L_CONF_REG_A = 0x00;
final static byte HMC5883L_CONF_REG_B = 0x01;
// mode register
final static byte HMC5883L_MODE_REG = 0x02;
// data register
final static byte HMC5883L_X_MSB_REG = 0;
final static byte HMC5883L_X_LSB_REG = 1;
final static byte HMC5883L_Z_MSB_REG = 2;
final static byte HMC5883L_Z_LSB_REG = 3;
final static byte HMC5883L_Y_MSB_REG = 4;
final static byte HMC5883L_Y_LSB_REG = 5;
final static byte DATA_REG_SIZE = 6;
// status register
final static byte HMC5883L_STATUS_REG = 0x09;
// ID registers
final static byte HMC5883L_ID_A_REG = 0x0A;
final static byte HMC5883L_ID_B_REG = 0x0B;
final static byte HMC5883L_ID_C_REG = 0x0C;
final static byte HMC5883L_CONT_MODE = 0x00;
final static byte HMC5883L_DATA_REG = 0x03;
// scales
final static byte GA_0_88_REG = ((byte) (0x00 << 5));
final static byte GA_1_3_REG = ((byte) (0x01 << 5));
final static byte GA_1_9_REG = ((byte) (0x02 << 5));
final static byte GA_2_5_REG = ((byte) (0x03 << 5));
final static byte GA_4_0_REG = ((byte) (0x04 << 5));
final static byte GA_4_7_REG = ((byte) (0x05 << 5));
final static byte GA_5_6_REG = ((byte) (0x06 << 5));
final static byte GA_8_1_REG = ((byte) (0x07 << 5));
// digital resolutions
final static float SCALE_0_73_MG = 0.73f;
final static float SCALE_0_92_MG = 0.92f;
final static float SCALE_1_22_MG = 1.22f;
final static float SCALE_1_52_MG = 1.52f;
final static float SCALE_2_27_MG = 2.27f;
final static float SCALE_2_56_MG = 2.56f;
final static float SCALE_3_03_MG = 3.03f;
final static float SCALE_4_35_MG = 4.35f;
public static void main(String[] args) throws InterruptedException {
float direction = 0;
int x, y, z;
byte[] rx_tx_buf = new byte[MAX_BUFFER_LENGTH];
byte[] conf_buf = new byte[CONF_BUFFER_LENGTH];
//! [Interesting]
I2c i2c = new I2c(0);
i2c.address(HMC5883L_I2C_ADDR);
conf_buf[0] = HMC5883L_CONF_REG_B;
conf_buf[1] = GA_1_3_REG;
i2c.write(conf_buf);
//! [Interesting]
i2c.address(HMC5883L_I2C_ADDR);
conf_buf[0] = HMC5883L_MODE_REG;
conf_buf[1] = HMC5883L_CONT_MODE;
i2c.write(conf_buf);
while (true) {
i2c.address(HMC5883L_I2C_ADDR);
i2c.writeByte(HMC5883L_DATA_REG);
i2c.address(HMC5883L_I2C_ADDR);
i2c.read(rx_tx_buf);
x = (rx_tx_buf[HMC5883L_X_MSB_REG] << 8) | rx_tx_buf[HMC5883L_X_LSB_REG];
z = (rx_tx_buf[HMC5883L_Z_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Z_LSB_REG];
y = (rx_tx_buf[HMC5883L_Y_MSB_REG] << 8) | rx_tx_buf[HMC5883L_Y_LSB_REG];
direction = (float) Math.atan2(y * SCALE_0_92_MG, x * SCALE_0_92_MG);
if (direction < 0)
direction += 2 * Math.PI;
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,
z * SCALE_0_92_MG));
System.out.println(String.format("Heading : %f\n", direction * 180 / Math.PI));
Thread.sleep(1000);
}
}
}
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