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
00022 #define REG_CTRL_REG_1    0x2A
00023 #define REG_OUT_X_MSB     0x01
00024 #define REG_OUT_Y_MSB     0x03
00025 #define REG_OUT_Z_MSB     0x05
00026 
00027 #define UINT14_MAX        16383
00028 
00029 MMA8451Q::MMA8451Q(PinName sda, PinName scl, int addr) : m_i2c(sda, scl), m_addr(addr) {
00030     // activate the peripheral
00031     uint8_t data[2] = {REG_CTRL_REG_1, 0x01};
00032     writeRegs(data, 2);
00033 }
00034 
00035 MMA8451Q::~MMA8451Q() { }
00036 
00037 uint8_t MMA8451Q::getWhoAmI() {
00038     uint8_t who_am_i = 0;
00039     readRegs(REG_WHO_AM_I, &who_am_i, 1);
00040     return who_am_i;
00041 }
00042 
00043 float MMA8451Q::getAccX() {
00044     return (float(getAccAxis(REG_OUT_X_MSB))/4096.0);
00045 }
00046 
00047 float MMA8451Q::getAccY() {
00048     return (float(getAccAxis(REG_OUT_Y_MSB))/4096.0);
00049 }
00050 
00051 float MMA8451Q::getAccZ() {
00052     return (float(getAccAxis(REG_OUT_Z_MSB))/4096.0);
00053 }
00054 
00055 void MMA8451Q::setGLimit() {
00056     uint8_t data[2] = {REG_CTRL_REG_1, 0x00};
00057     writeRegs(data, 2); // put in standby
00058     data[0] = XYZ_DATA_CFG;
00059     data[1] = 0x02;
00060     writeRegs(data, 2); // change g limit
00061     data[0] = REG_CTRL_REG_1;
00062     data[1] = 0x01;
00063     writeRegs(data, 2); // make active
00064 }
00065 
00066 void MMA8451Q::getAccAllAxis(float * res) {
00067     res[0] = getAccX();
00068     res[1] = getAccY();
00069     res[2] = getAccZ();
00070 }
00071 
00072 void MMA8451Q::readRegs(int addr, uint8_t * data, int len) {
00073     char t[1] = {addr};
00074     m_i2c.write(m_addr, t, 1, true);
00075     m_i2c.read(m_addr, (char *)data, len);
00076 }
00077 
00078 void MMA8451Q::writeRegs(uint8_t * data, int len) {
00079     m_i2c.write(m_addr, (char *)data, len);
00080 }
00081 
00082 int16_t MMA8451Q::getAccAxis(uint8_t addr) {
00083     int16_t acc;
00084     uint8_t res[2];
00085     readRegs(addr, res, 2);
00086 
00087     acc = (res[0] << 6) | (res[1] >> 2);
00088     if (acc > UINT14_MAX/2)
00089         acc -= UINT14_MAX;
00090 
00091     return acc;
00092 }
00093