MMA8451Q.cpp

00001 /**
00002  * MMA8451Q 3-Axis, 14-bit/8-bit Digital Accelerometer
00003  */
00004  
00005 #include "mbed.h"
00006 #include "MMA8451Q.h"
00007 
00008 #define REG_STATUS           0x00 // when F_MODE = 00
00009 #define REG_FIFO_STATUS      0x00 // when F_MODE > 0
00010 #define REG_XYZ_FIFO         0x01 // Root pointer to XYZ FIFO data
00011 #define REG_OUT_X_MSB        0x01 // 8 MSBs of 14-bit sample
00012 #define REG_OUT_X_LSB        0x02 // 6 LSBs of 14-bit sample
00013 #define REG_OUT_Y_MSB        0x03 
00014 #define REG_OUT_Y_LSB        0x04
00015 #define REG_OUT_Z_MSB        0x05
00016 #define REG_OUT_Z_LSB        0x06
00017 #define REG_F_SETUP          0x09 // FIFO setup
00018 #define REG_TRIG_CFG         0x0A // Map of FIFO daa capture events
00019 #define REG_SYSMOD           0x0B // Current System Mode
00020 #define REG_INT_SOURCE       0x0C // Interrupt status
00021 #define REG_WHO_AM_I         0x0D // Device ID (0x1A)
00022 #define REG_XYZ_DATA_CFG     0x0E // Dynamic Range Settings
00023 #define REG_HP_FILTER_CUTOFF 0x0F // Cutoff freq is set to 16Hz@800Hz
00024 #define REG_PL_STATUS        0x10 // Landscape/Portrait orientation status
00025 #define REG_PL_CFG           0x11 // Landscape/Portrait configuration
00026 #define REG_PL_COUNT         0x12 // Landscape/Portrait debounce counter 
00027 #define REG_PL_BF_ZCOMP      0x13 // Back/Front, Z-Lock Trip threshold
00028 #define REG_P_L_THS_REG      0x14 // Portrait to Landscape Trip Angle is 29 degree
00029 #define REG_FF_MT_CFG        0x15 // Freefall/Motion function block configuration
00030 #define REG_FF_MT_SRC        0x16 // Freefall/Motion event source register
00031 #define REG_FF_MT_THS        0x17 // Freefall/Motion threshold register
00032 #define REG_FF_MT_COUNT      0x18 // Freefall/Motion debounce counter
00033 // TRANSIENT
00034 #define REG_TRANSIENT_CFG    0x1D // Transient functional block configuration
00035 #define REG_TRANSIENT_SRC    0x1E // Transient event status register
00036 #define REG_TRANSIENT_THS    0x1F // Transient event threshold
00037 #define REG_TRANSIENT_COUNT  0x20 // Transient debounce counter
00038 // PULSE
00039 #define REG_PULSE_CFG        0x21 // ELE, Double_XYZ or Single_XYZ
00040 #define REG_PULSE_SRC        0x22 // EA, Double_XYZ or Single_XYZ
00041 #define REG_PULSE_THSX       0x23 // X pulse threshold
00042 #define REG_PULSE_THSY       0x24 // Y pulse threshold
00043 #define REG_PULSE_THSZ       0x25 // Z pulse threshold
00044 #define REG_PULSE_TMLT       0x26 // Time limit for pulse
00045 #define REG_PULSE_LTCY       0x27 // Latency time for 2nd pulse
00046 #define REG_PULSE_WIND       0x28 // Window time for 2nd pulse
00047 #define REG_ASLP_COUNT       0x29 // Counter setting for Auto-SLEEP
00048 // Control Registers
00049 #define REG_CTRL_REG1        0x2A // ODR = 800Hz, STANDBY Mode
00050 #define REG_CTRL_REG2        0x2B // Sleep Enable, OS Modes, RST, ST
00051 #define REG_CTRL_REG3        0x2C // Wake from Sleep, IPOL, PP_OD
00052 #define REG_CTRL_REG4        0x2D // Interrupt enable register
00053 #define REG_CTRL_REG5        0x2E // Interrupt pin (INT1/INT2) map
00054 // User Offset
00055 #define REG_OFF_X            0x2F // X-axis offset adjust
00056 #define REG_OFF_Y            0x30 // Y-axis offset adjust
00057 #define REG_OFF_Z            0x31 // Z-axis offset adjust
00058 
00059 // Value definitions
00060 #define BIT_TRIG_TRANS       0x20  // Transient interrupt trigger bit
00061 #define BIT_TRIG_LNDPRT      0x10  // Landscape/Portrati Orientation
00062 #define BIT_TRIG_PULSE       0x08  // Pulse interrupt trigger bit
00063 #define BIT_TRIG_FF_MT       0x04  // Freefall/Motion trigger bit
00064 
00065 MMA8451Q::MMA8451Q(I2C *i2c, int addr) : m_addr(addr<<1) {
00066     // activate the peripheral
00067     p_i2c = i2c ;
00068     uint8_t data[2] = {REG_CTRL_REG1, 0x01};
00069     writeRegs(data, 2);
00070 }
00071 
00072 MMA8451Q::~MMA8451Q() { }
00073 
00074 int MMA8451Q::readRegs(int addr, uint8_t * data, int len) 
00075 {
00076     char t[1] = {addr};
00077     int result ;
00078     result = p_i2c->write(m_addr, t, 1, true);
00079     if (result == 0) {
00080         result = p_i2c->read(m_addr, (char *)data, len);
00081     }
00082     return( result ) ;
00083 }
00084 
00085 int MMA8451Q::writeRegs(uint8_t * data, int len) 
00086 {
00087     int result ;
00088     result = p_i2c->write(m_addr, (char *)data, len);
00089     return( result ) ;
00090 }
00091 
00092 int MMA8451Q::getAllRawData(int16_t value[])
00093 {
00094     int result ;
00095     uint8_t data[6] ;
00096     result = readRegs(REG_OUT_X_MSB, data, 6) ;
00097     if (result == 0) {
00098         value[0] = ((int16_t)((data[0] << 8) | data[1])) >> 2 ;
00099         value[1] = ((int16_t)((data[2] << 8) | data[3])) >> 2 ;
00100         value[2] = ((int16_t)((data[4] << 8) | data[5])) >> 2 ;
00101     }
00102     return( result ) ;
00103 }
00104 
00105 int MMA8451Q::getAllData(float fvalue[])
00106 {
00107     int result ;
00108     uint8_t data[6] ;
00109     result = readRegs(REG_OUT_X_MSB, data, 6) ;
00110     if (result == 0) {
00111         fvalue[0] = (float)((int16_t)((data[0] << 8) | data[1])) / 16384.0 ;
00112         fvalue[1] = (float)((int16_t)((data[2] << 8) | data[3])) / 16384.0 ;
00113         fvalue[2] = (float)((int16_t)((data[4] << 8) | data[5])) / 16384.0 ;
00114     }
00115     return( result ) ;
00116 }
00117 
00118 int16_t MMA8451Q::getRawData(uint8_t addr)
00119 {
00120     int16_t value ;
00121     uint8_t data[2] ;
00122     readRegs(addr, data, 2) ;
00123     value = ((int16_t)((data[0] << 8) | data[1])) >> 2 ;
00124     return( value ) ;
00125 }
00126 
00127 int16_t MMA8451Q::getRawX(void) 
00128 {
00129     int16_t value ;
00130     value = getRawData(REG_OUT_X_MSB) ;
00131     return( value ) ;
00132 }
00133 
00134 int16_t MMA8451Q::getRawY(void) 
00135 {
00136     int16_t value ;
00137     value = getRawData(REG_OUT_Y_MSB) ;
00138     return( value ) ;
00139 }
00140 
00141 int16_t MMA8451Q::getRawZ(void) 
00142 {
00143     int16_t value ;
00144     value = getRawData(REG_OUT_Z_MSB) ;
00145     return( value ) ;
00146 }
00147   
00148 float MMA8451Q::getAccX(void)
00149 {
00150     return(((float)getRawX())/4096.0) ;
00151 }
00152 
00153 float MMA8451Q::getAccY(void) 
00154 {
00155     return(((float)getRawY())/4096.0) ;
00156 }
00157 
00158 float MMA8451Q::getAccZ(void) 
00159 {
00160     return(((float)getRawZ())/4096.0) ;
00161 }