Diff: HMC5883L.cpp

Revision:

0:e5f8da308b60

Child:

2:bbc9ad18fd3e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HMC5883L.cpp	Wed Aug 05 12:59:07 2015 +0000
@@ -0,0 +1,156 @@
+/*   HMC5883L Digital Compass Library
+*
+*    @author: Baser Kandehir 
+*    @date: August 5, 2015
+*    @license: MIT license
+*     
+*   Copyright (c) 2015, Baser Kandehir, baser.kandehir@ieee.metu.edu.tr
+*
+*   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.
+*
+*/
+
+// Some part of the code is adapted from Adafruit HMC5883 library
+
+#include "HMC5883L.h"
+
+/* NUCLEO F411RE board */
+I2C i2c(D14, D15);         // setup i2c (SDA,SCL)  
+
+static float Gauss_LSB_XY = 1100.0F; // Varies with gain
+static float Gauss_LSB_Z =  980.0F;  // Varies with gain
+ 
+void HMC5883L::setMagGain(MagGain gain)
+{
+    writeByte(HMC5883L_ADDRESS, CONFIG_B, (int8_t)gain);    
+    
+    switch(gain)
+    {
+        case MagGain_13:
+            Gauss_LSB_XY = 1100;
+            Gauss_LSB_Z  = 980;
+            break;
+        case MagGain_19:
+            Gauss_LSB_XY = 855;
+            Gauss_LSB_Z  = 760;
+            break;
+        case MagGain_25:
+            Gauss_LSB_XY = 670;
+            Gauss_LSB_Z  = 600;
+            break;
+        case MagGain_40:
+            Gauss_LSB_XY = 450;
+            Gauss_LSB_Z  = 400;
+            break;
+        case MagGain_47:
+            Gauss_LSB_XY = 400;
+            Gauss_LSB_Z  = 255;
+            break;
+        case MagGain_56:
+            Gauss_LSB_XY = 330;
+            Gauss_LSB_Z  = 295;
+            break;
+        case MagGain_81:
+            Gauss_LSB_XY = 230;
+            Gauss_LSB_Z  = 205;
+            break;
+    }  
+}
+
+void HMC5883L::writeByte(uint8_t address, uint8_t regAddress, uint8_t data)
+{
+    char data_write[2];
+    data_write[0]=regAddress;           // I2C sends MSB first. Namely  >>|regAddress|>>|data|
+    data_write[1]=data;
+    i2c.write(address,data_write,2,0);  // i2c.write(int address, char* data, int length, bool repeated=false);  
+}
+
+char HMC5883L::readByte(uint8_t address, uint8_t regAddress)
+{
+    char data_read[1];                   // will store the register data    
+    char data_write[1];
+    data_write[0]=regAddress;
+    i2c.write(address,data_write,1,1);   // repeated = true
+    i2c.read(address,data_read,1,0);     // read the data and stop
+    return data_read[0];
+} 
+
+void HMC5883L::readBytes(uint8_t address, uint8_t regAddress, uint8_t byteNum, uint8_t* dest)
+{
+    char data[10],data_write[1];  
+    data_write[0]=regAddress;      
+    i2c.write(address,data_write,1,1);
+    i2c.read(address,data,byteNum,0);
+    for(int i=0;i<byteNum;i++)          // equate the addresses
+        dest[i]=data[i];
+}
+
+void HMC5883L::init()
+{
+    writeByte(HMC5883L_ADDRESS, CONFIG_A, 0x78);  // Number of samples averaged: 8, Data output rate: 75 Hz
+    writeByte(HMC5883L_ADDRESS, MODE,     0x00);  // Continuous-Measurement Mode
+    setMagGain(MagGain_13);
+    wait_ms(10);
+}
+
+void HMC5883L::readMagData(float* dest)
+{
+    uint8_t rawData[6]; // x,y,z mag data
+    
+    /* Read six raw data registers sequentially and write them into data array */
+    readBytes(HMC5883L_ADDRESS, OUT_X_MSB, 6, &rawData[0]); 
+    
+    /* Turn the MSB LSB into signed 16-bit value */
+    dest[0] = (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]);  // MAG_XOUT
+    dest[2] = (int16_t)(((int16_t)rawData[2]<<8) | rawData[3]);  // MAG_ZOUT
+    dest[1] = (int16_t)(((int16_t)rawData[4]<<8) | rawData[5]);  // MAG_YOUT 
+    
+    /* Convert raw data to magnetic field values in microtesla */
+     dest[0] = dest[0] / Gauss_LSB_XY * GAUSS_TO_MICROTESLA;
+     dest[1] = dest[1] / Gauss_LSB_XY * GAUSS_TO_MICROTESLA;
+     dest[2] = dest[2] / Gauss_LSB_Z  * GAUSS_TO_MICROTESLA;
+}
+
+double HMC5883L::getHeading()
+{
+    float magData[3];
+    readMagData(magData);
+    
+    /* Calculate the heading while Z axis of the module is pointing up */
+    double heading = atan2(magData[1], magData[0]);
+    
+    // After calculating heading declination angle should be added to heading which is the error of the magnetic field in specific location.
+    // declinationAngle can be found here http://www.magnetic-declination.com/
+    // For Ankara (my location) declinationAngle is ~5.5 degrees (0.096 radians)
+    float declinationAngle = 0.096;
+    heading += declinationAngle;
+    
+    // Correct for when signs are reversed.
+    if(heading < 0)
+        heading += 2*PI;
+    
+    // Check for wrap due to addition of declination.
+    if(heading > 2*PI)
+        heading -= 2*PI;
+    
+    /* Convert radian to degrees */
+    heading = heading * 180 / PI;  
+    
+    return heading;    
+}