LSM303DLHC.cpp

00001 /** LSM303DLHC Interface Library
00002  *
00003  * base on code by Michael Shimniok http://bot-thoughts.com
00004  *
00005  *  and on test program by @tosihisa and 
00006  *
00007  *  and on Pololu sample library for LSM303DLHC breakout by ryantm:
00008  *
00009  * Copyright (c) 2011 Pololu Corporation. For more information, see
00010  *
00011  * http://www.pololu.com/
00012  * http://forum.pololu.com/
00013  *
00014  * Permission is hereby granted, free of charge, to any person
00015  * obtaining a copy of this software and associated documentation
00016  * files (the "Software"), to deal in the Software without
00017  * restriction, including without limitation the rights to use,
00018  * copy, modify, merge, publish, distribute, sublicense, and/or sell
00019  * copies of the Software, and to permit persons to whom the
00020  * Software is furnished to do so, subject to the following
00021  * conditions:
00022  *
00023  * The above copyright notice and this permission notice shall be
00024  * included in all copies or substantial portions of the Software.
00025  * 
00026  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00027  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
00028  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00029  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
00030  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
00031  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
00032  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
00033  * OTHER DEALINGS IN THE SOFTWARE.
00034  */
00035 #include "mbed.h"
00036 #include "LSM303DLHC.h"
00037 
00038 
00039 const int addr_acc = 0x32;
00040 const int addr_mag = 0x3c;
00041 
00042 enum REG_ADDRS {
00043     /* --- Mag --- */
00044     CRA_REG_M   = 0x00,
00045     CRB_REG_M   = 0x01,
00046     MR_REG_M    = 0x02,
00047     OUT_X_M     = 0x03,
00048     OUT_Y_M     = 0x05,
00049     OUT_Z_M     = 0x07,
00050     /* --- Acc --- */
00051     CTRL_REG1_A = 0x20,
00052     CTRL_REG4_A = 0x23,
00053     OUT_X_A     = 0x28,
00054     OUT_Y_A     = 0x2A,
00055     OUT_Z_A     = 0x2C,
00056 };
00057 
00058 bool LSM303DLHC::write_reg(int addr_i2c,int addr_reg, char v)
00059 {
00060     char data[2] = {addr_reg, v}; 
00061     return LSM303DLHC::_LSM303.write(addr_i2c, data, 2) == 0;
00062 }
00063 
00064 bool LSM303DLHC::read_reg(int addr_i2c,int addr_reg, char *v)
00065 {
00066     char data = addr_reg; 
00067     bool result = false;
00068     
00069     __disable_irq();
00070     if ((_LSM303.write(addr_i2c, &data, 1) == 0) && (_LSM303.read(addr_i2c, &data, 1) == 0)){
00071         *v = data;
00072         result = true;
00073     }
00074     __enable_irq();
00075     return result;
00076 }
00077 
00078 
00079 LSM303DLHC::LSM303DLHC(PinName sda, PinName scl):
00080     _LSM303(sda, scl)
00081 {
00082     char reg_v;
00083     _LSM303.frequency(100000);
00084         
00085     reg_v = 0;
00086     
00087     reg_v |= 0x27;          /* X/Y/Z axis enable. */
00088     write_reg(addr_acc,CTRL_REG1_A,reg_v);
00089 
00090     reg_v = 0;
00091    // reg_v |= 0x01 << 6;     /* 1: data MSB @ lower address */
00092     reg_v = 0x01 << 4;     /* +/- 4g */
00093     write_reg(addr_acc,CTRL_REG4_A,reg_v);
00094 
00095     /* -- mag --- */
00096     reg_v = 0;
00097     reg_v |= 0x04 << 2;     /* Minimum data output rate = 15Hz */
00098     write_reg(addr_mag,CRA_REG_M,reg_v);
00099 
00100     reg_v = 0;
00101     reg_v |= 0x01 << 5;     /* +-1.3Gauss */
00102     //reg_v |= 0x07 << 5;     /* +-8.1Gauss */
00103     write_reg(addr_mag,CRB_REG_M,reg_v);
00104 
00105     reg_v = 0;              /* Continuous-conversion mode */
00106     write_reg(addr_mag,MR_REG_M,reg_v);
00107 }
00108 
00109 
00110 static float magn_ellipsoid_center_x = -0.0446786;
00111 static float magn_ellipsoid_center_y = 0.0251516;
00112 static float magn_ellipsoid_center_z = -0.44229;
00113 
00114 static float magn_ellipsoid_transform_0_x = 0.978841;
00115 static float magn_ellipsoid_transform_0_y = 0.0078251;
00116 static float magn_ellipsoid_transform_0_z = 0.0120719;
00117 static float magn_ellipsoid_transform_1_x = 0.0078251;
00118 static float magn_ellipsoid_transform_1_y = 0.996114;
00119 static float magn_ellipsoid_transform_1_z = 0.00302665;
00120 static float magn_ellipsoid_transform_2_x = 0.0120719;
00121 static float magn_ellipsoid_transform_2_y = 0.00302665;
00122 static float magn_ellipsoid_transform_2_z = 0.936561;
00123 bool LSM303DLHC::read(float *ax, float *ay, float *az, float *mx, float *my, float *mz) {
00124     char acc[6], mag[6];
00125  
00126     if (recv(addr_acc, OUT_X_A, acc, 6) && recv(addr_mag, OUT_X_M, mag, 6)) {
00127         *ax = float(short(acc[1] << 8 | acc[0]))/8192;  //32768/4=8192
00128         *ay =  float(short(acc[3] << 8 | acc[2]))/8192;
00129         *az =  float(short(acc[5] << 8 | acc[4]))/8192;
00130         //full scale magnetic readings are from -2048 to 2047
00131         
00132         //gain is x,y = 1100; z = 980 LSB/gauss
00133         float mx_tmp = float(short(mag[0] << 8 | mag[1]))/1100 - magn_ellipsoid_center_x;
00134         float my_tmp = float(short(mag[2] << 8 | mag[3]))/1100 - magn_ellipsoid_center_y;
00135         float mz_tmp = float(short(mag[4] << 8 | mag[5]))/980 - magn_ellipsoid_center_z;
00136         *mx = magn_ellipsoid_transform_0_x * mx_tmp + magn_ellipsoid_transform_0_y * my_tmp + magn_ellipsoid_transform_0_z * mz_tmp - 0.0791235566;
00137         *my = magn_ellipsoid_transform_1_x * mx_tmp + magn_ellipsoid_transform_1_y * my_tmp + magn_ellipsoid_transform_1_z * mz_tmp + 0.8915525079;
00138         *mz = magn_ellipsoid_transform_2_x * mx_tmp + magn_ellipsoid_transform_2_y * my_tmp + magn_ellipsoid_transform_2_z * mz_tmp + 0.5963887572;
00139  
00140         return true;
00141     }
00142  
00143     return false;
00144 }
00145 
00146 
00147 bool LSM303DLHC::recv(char sad, char sub, char *buf, int length) {
00148     if (length > 1) sub |= 0x80;
00149  
00150     return _LSM303.write(sad, &sub, 1, true) == 0 && _LSM303.read(sad, buf, length) == 0;
00151 }