MMA8451Q.cpp

00001 /* Copyright (c) 2010-2011 mbed.org, MIT License
00002 *
00003 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
00004 * and associated documentation files (the "Software"), to deal in the Software without
00005 * restriction, including without limitation the rights to use, copy, modify, merge, publish,
00006 * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
00007 * Software is furnished to do so, subject to the following conditions:
00008 *
00009 * The above copyright notice and this permission notice shall be included in all copies or
00010 * substantial portions of the Software.
00011 *
00012 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
00013 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00014 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
00015 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00016 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00017 */
00018 
00019 #include "MMA8451Q.h"
00020 
00021 #define REG_WHO_AM_I      0x0D //13
00022 #define REG_CTRL_REG_1    0x2A
00023 #define REG_CTRL_REG_2    0x2B
00024 #define REG_OUT_X_MSB     0x01
00025 #define REG_OUT_Y_MSB     0x03
00026 #define REG_OUT_Z_MSB     0x05
00027 
00028 #define XYZ_DATA_CFG      0x0E
00029 #define HP_FILTER_CUTOFF  0x0F
00030 #define PL_CFG            0x11 //configure 
00031 #define TRANSIENT_COUNT   0x20
00032 
00033 #define UINT14_MAX        16383
00034 
00035 //#define LNOISE
00036 
00037 MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) {  
00038 
00039 #ifdef LNOISE
00040 
00041     // LNOISE
00042     uint8_t dataExt[3];
00043     uint8_t data[2] = {REG_CTRL_REG_1, 0x0c}; // 0x1100 = DR0 & LNOISE (2.5ms b/w samples)
00044     writeRegs(data, 2);    
00045     
00046     /*
00047     data[0] = REG_CTRL_REG_2;
00048     data[1] = 0x02;                 // Set MODS[1:0] to 0b10 for High Res mode
00049     writeRegs(data, 3); 
00050     */
00051     
00052     // activate the peripheral
00053     dataExt[0] = HP_FILTER_CUTOFF;
00054     dataExt[1] = 0x00;                 
00055     dataExt[2] = 0x01;                 /* Set the Pulse_LPF_EN */
00056     writeRegs(dataExt, 3);      
00057   
00058     // activate the peripheral
00059     data[1] = 0x01;   
00060     writeRegs(data, 2);    
00061     
00062 #else
00063 
00064     // activate
00065     //uint8_t data[2] = {REG_CTRL_REG_1, 0x01};
00066     //writeRegs(data, 2);   
00067     
00068     // activate
00069     uint8_t data[2] = {REG_CTRL_REG_1, 0x08}; 
00070     writeRegs(data, 2);   
00071     
00072     // activate the peripheral
00073     data[1] = 0x01;   
00074     writeRegs(data, 2); 
00075     
00076     
00077     
00078 #endif
00079       
00080 }
00081 
00082 MMA8451Q::~MMA8451Q() { }
00083 
00084 uint8_t MMA8451Q::getWhoAmI() {
00085     uint8_t who_am_i = 0;
00086     readRegs(REG_WHO_AM_I, &who_am_i, 1);
00087     return who_am_i;
00088 }
00089 
00090 float MMA8451Q::getAccX() {
00091     return (float(getAccAxis(REG_OUT_X_MSB))/4096.0);
00092 }
00093 
00094 float MMA8451Q::getAccY() {
00095     return (float(getAccAxis(REG_OUT_Y_MSB))/4096.0);
00096 }
00097 
00098 float MMA8451Q::getAccZ() {
00099     return (float(getAccAxis(REG_OUT_Z_MSB))/4096.0);
00100 }
00101 
00102 void MMA8451Q::getAccAllAxis(float * res) {
00103     res[0] = getAccX();
00104     res[1] = getAccY();
00105     res[2] = getAccZ();
00106 }
00107 
00108 int16_t MMA8451Q::getAccAxis(uint8_t addr) {
00109     int16_t acc;
00110     uint8_t res[2];
00111     readRegs(addr, res, 2);
00112 
00113     acc = (res[0] << 6) | (res[1] >> 2);
00114     if (acc > UINT14_MAX/2)
00115         acc -= UINT14_MAX;
00116 
00117     return acc;
00118 }
00119 
00120 void MMA8451Q::readRegs(int addr, uint8_t * data, int len) {
00121     char t[1] = {addr};
00122     m_i2c.write(m_addr, t, 1, true);
00123     m_i2c.read(m_addr, (char *)data, len);
00124 }
00125 
00126 void MMA8451Q::writeRegs(uint8_t * data, int len) {
00127     m_i2c.write(m_addr, (char *)data, len);
00128 }