LIS302.cpp

00001 /* mbed LIS302 Accelerometer Library
00002  * Copyright (c) 2008-2010, sford, cstyles, wreynolds
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00023 #include "LIS302.h"
00024 #include "mbed.h"
00025 
00026 #define LIS302_WHOAMI               0x0F
00027 #define LIS302_CTRL_REG1            0x20
00028 #define LIS302_CTRL_REG2            0x21
00029 #define LIS302_CTRL_REG3            0x22
00030 #define LIS302_HP_FILTER_RST        0x23
00031 #define LIS302_STATUS_REG           0x27
00032 #define LIS302_OUTX                 0x29
00033 #define LIS302_OUTY                 0x2B
00034 #define LIS302_OUTZ                 0x2D
00035 #define LIS302_FF_WU_CFG1           0x30
00036 #define LIS302_FF_WU_SRC_1          0x31
00037 #define LIS302_FF_WU_THS_1          0x32
00038 #define LIS302_FF_WU_DURATION_1     0x33
00039 #define LIS302_FF_WU_CFG_2          0x34
00040 #define LIS302_FF_WU_SRC_2          0x35
00041 #define LIS302_FF_WU_THS_2          0x36
00042 #define LIS302_FF_WU_DURATION_2     0x37
00043 #define LIS302_CLICK_CFG            0x38
00044 #define LIS302_CLICK_SRC            0x39
00045 #define LIS302_CLICK_THSY_X         0x3B
00046 #define LIS302_CLICK_THSZ           0x3C
00047 #define LIS302_READ                 0x80
00048 #define LIS302_WRITE                0x00
00049 
00050 #define LIS302_STATUS_X_AVAILABLE 0x1
00051 #define LIS302_STATUS_Y_AVAILABLE 0x2
00052 #define LIS302_STATUS_Z_AVAILABLE 0x4
00053 
00054 #define FACTOR_2g 55.6
00055 #define FACTOR_8g 13.9
00056 
00057 LIS302::LIS302(PinName mosi, PinName miso, PinName clk, PinName ncs)
00058     : _spi(mosi, miso, clk), _ncs(ncs) {
00059 
00060     // Make sure CS is high
00061     _ncs = 1;
00062 
00063     // Set up the spi interface
00064     _spi.format(8, 3);
00065     _spi.frequency(1000000);
00066 
00067     // Write to CTRL_REG1
00068     _ncs = 0;
00069     _spi.write(LIS302_WRITE | LIS302_CTRL_REG1);
00070     _spi.write (0x47);
00071     _ncs = 1;
00072 
00073     // Write to CTRL_REG2
00074     _ncs = 0;
00075     _spi.write(LIS302_WRITE | LIS302_CTRL_REG2);
00076     _spi.write (0x0);  // This is default anyway
00077     _ncs = 1;
00078 
00079     // Write to CTRL_REG3
00080     _ncs = 0;
00081     _spi.write(LIS302_WRITE | LIS302_CTRL_REG3);
00082     _spi.write (0x0);  // This is default anyway
00083     _ncs = 1;
00084 
00085     range(0);
00086     calibrate();
00087 }
00088 
00089 float LIS302::x() {
00090     // wait for a new sample
00091     while(!(status() & LIS302_STATUS_X_AVAILABLE));
00092 
00093     _ncs = 0;
00094     _spi.write(LIS302_READ | LIS302_OUTX);
00095     signed char raw = _spi.write(0x00);
00096     _ncs = 1;
00097 
00098     float gradient = (2.0/(_maxx-_minx));
00099     return (gradient*(float)(raw)/_factor)+((-gradient*_maxx)+1);
00100 }
00101 
00102 float LIS302::y() {
00103     // wait for a new sample
00104     while(!(status() & LIS302_STATUS_Y_AVAILABLE));
00105 
00106     _ncs = 0;
00107     _spi.write(LIS302_READ | LIS302_OUTY);
00108     signed char raw = _spi.write(0x00);
00109     _ncs = 1;
00110 
00111     float gradient = (2.0/(_maxy-_miny));
00112     return (gradient*(float)(raw)/_factor)+((-gradient*_maxy)+1);
00113 }
00114 
00115 float LIS302::z() {
00116     // wait for a new sample
00117     while(!(status() & LIS302_STATUS_Z_AVAILABLE));
00118 
00119     _ncs = 0;
00120     _spi.write(LIS302_READ | LIS302_OUTZ);
00121     signed char raw = _spi.write(0x00);
00122     _ncs = 1;
00123 
00124     float gradient = (2.0/(_maxz-_minz));
00125     return (gradient*(float)(raw)/_factor)+((-gradient*_maxz)+1);
00126 }
00127 
00128 void LIS302::range(int g) {
00129 
00130     // fetch the current CRTL_REG1
00131     _ncs = 0;
00132     _spi.write(LIS302_READ | LIS302_CTRL_REG1);
00133     int value = _spi.write(0x00);
00134     _ncs = 1;
00135 
00136     // set the range bit, and the calculation factor
00137     if(g) {
00138         value |= 0x20; // 8g
00139         _factor = FACTOR_8g;
00140     } else {
00141         value &= ~0x20; // 2g
00142         _factor = FACTOR_2g;
00143     }
00144 
00145     _ncs = 0;
00146     _spi.write(LIS302_WRITE | LIS302_CTRL_REG1);
00147     _spi.write(value);
00148     _ncs = 1;
00149 }
00150 
00151 void LIS302::calibrate(float maxx, float minx, float maxy, float miny, float maxz, float minz) {
00152     _maxx = maxx;
00153     _minx = minx;
00154     _maxy = maxy;
00155     _miny = miny;
00156     _maxz = maxz;
00157     _minz = minz;
00158 }
00159 
00160 int LIS302::whoami() {
00161     _ncs = 0;
00162     _spi.write(LIS302_READ | LIS302_WHOAMI);
00163     int value = _spi.write(0x00);
00164     _ncs = 1;
00165     return value;
00166 }
00167 
00168 int LIS302::status() {
00169     _ncs = 0;
00170     _spi.write(0xA7);
00171     int value = _spi.write(LIS302_READ | LIS302_STATUS_REG);
00172     _ncs = 1;
00173     return value;
00174 }