MMA8451Q8.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 // Modify to change full scale gravity range 141207 sc
00019 
00020 
00021 #include "MMA8451Q8.h"
00022 
00023 #define REG_WHO_AM_I      0x0D
00024 #define REG_CTRL_REG_1    0x2A
00025 #define REG_OUT_X_MSB     0x01
00026 #define REG_OUT_Y_MSB     0x03
00027 #define REG_OUT_Z_MSB     0x05
00028 #define XYZ_DATA_CFG      0x0E
00029 
00030 #define UINT14_MAX        16383
00031 
00032 #define MAX_2G            0x00
00033 #define MAX_4G            0x01
00034 #define MAX_8G            0x02
00035 
00036 #define NUM_DATA            2
00037 #define GSCALING          1024.0
00038 #define ADDRESS_INDEX       0
00039 #define DATA_INDEX          1
00040 
00041 float gScaling[3] = {4095.0,2048.0,1024.0}; //scaling for acceleration of gravity values
00042 
00043 MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) {
00044     // activate the peripheral
00045     uint8_t data[2] = {REG_CTRL_REG_1, 0x01};
00046     writeRegs(data, 2);
00047 }
00048 
00049 MMA8451Q::~MMA8451Q() { }
00050 
00051 uint8_t MMA8451Q::getWhoAmI() {
00052     uint8_t who_am_i = 0;
00053     readRegs(REG_WHO_AM_I, &who_am_i, 1);
00054     return who_am_i;
00055 }
00056 void MMA8451Q::setGLimit(int gSelect) {   
00057     uint8_t data[NUM_DATA] = {REG_CTRL_REG_1, 0x00};
00058     gChosen = gSelect;
00059     writeRegs(data, NUM_DATA); // put in standby
00060     data[ADDRESS_INDEX ] = XYZ_DATA_CFG;
00061     data[DATA_INDEX] = gChosen;
00062     writeRegs(data, 2);// change g limit
00063     data[ADDRESS_INDEX ] = REG_CTRL_REG_1;
00064     data[DATA_INDEX] = 0x01;
00065     writeRegs(data, 2); // make active
00066 }
00067 
00068 float MMA8451Q::getAccX() {
00069     return (float(getAccAxis(REG_OUT_X_MSB))/gScaling[gChosen]);
00070 }
00071 
00072 float MMA8451Q::getAccY() {
00073     return (float(getAccAxis(REG_OUT_Y_MSB))/gScaling[gChosen]);
00074 }
00075 
00076 float MMA8451Q::getAccZ() {
00077     return (float(getAccAxis(REG_OUT_Z_MSB))/gScaling[gChosen]);
00078 }
00079 
00080 void MMA8451Q::getAccAllAxis(float * res) {
00081     res[0] = getAccX();
00082     res[1] = getAccY();
00083     res[2] = getAccZ();
00084 }
00085 
00086 int16_t MMA8451Q::getAccAxis(uint8_t addr) {
00087     int16_t acc;
00088     uint8_t res[2];
00089     readRegs(addr, res, 2);
00090 
00091     acc = (res[0] << 6) | (res[1] >> 2);
00092     if (acc > UINT14_MAX/2)
00093         acc -= UINT14_MAX;
00094 
00095     return acc;
00096 }
00097 
00098 void MMA8451Q::readRegs(int addr, uint8_t * data, int len) {
00099     char t[1] = {addr};
00100     m_i2c.write(m_addr, t, 1, true);
00101     m_i2c.read(m_addr, (char *)data, len);
00102 }
00103 
00104 void MMA8451Q::writeRegs(uint8_t * data, int len) {
00105     m_i2c.write(m_addr, (char *)data, len);
00106 }