Diff: LSM9DS1.cpp

Revision:

0:e8167f37725c

Child:

1:87d535bf8c53

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LSM9DS1.cpp	Mon Oct 26 14:55:43 2015 +0000
@@ -0,0 +1,1197 @@
+/******************************************************************************
+SFE_LSM9DS1.cpp
+SFE_LSM9DS1 Library Source File
+Jim Lindblom @ SparkFun Electronics
+Original Creation Date: February 27, 2015
+https://github.com/sparkfun/LSM9DS1_Breakout
+
+This file implements all functions of the LSM9DS1 class. Functions here range
+from higher level stuff, like reading/writing LSM9DS1 registers to low-level,
+hardware reads and writes. Both SPI and I2C handler functions can be found
+towards the bottom of this file.
+
+Development environment specifics:
+    IDE: Arduino 1.6
+    Hardware Platform: Arduino Uno
+    LSM9DS1 Breakout Version: 1.0
+
+This code is beerware; if you see me (or any other SparkFun employee) at the
+local, and you've found our code helpful, please buy us a round!
+
+Distributed as-is; no warranty is given.
+******************************************************************************/
+
+#include "LSM9DS1.h"
+#include "LSM9DS1_Registers.h"
+#include "LSM9DS1_Types.h"
+//#include <Wire.h> // Wire library is used for I2C
+//#include <SPI.h>  // SPI library is used for...SPI.
+
+//#if defined(ARDUINO) && ARDUINO >= 100
+//  #include "Arduino.h"
+//#else
+//  #include "WProgram.h"
+//#endif
+
+#define LSM9DS1_COMMUNICATION_TIMEOUT 1000
+
+float magSensitivity[4] = {0.00014, 0.00029, 0.00043, 0.00058};
+extern Serial pc;
+
+LSM9DS1::LSM9DS1(PinName sda, PinName scl, uint8_t xgAddr, uint8_t mAddr)
+    :i2c(sda, scl)
+{
+    init(IMU_MODE_I2C, xgAddr, mAddr); // dont know about 0xD6 or 0x3B
+}
+/* cw
+LSM9DS1::LSM9DS1()
+{
+    init(IMU_MODE_I2C, LSM9DS1_AG_ADDR(1), LSM9DS1_M_ADDR(1));
+}
+
+LSM9DS1::LSM9DS1(interface_mode interface, uint8_t xgAddr, uint8_t mAddr)
+{
+    init(interface, xgAddr, mAddr);
+}
+*/
+
+void LSM9DS1::init(interface_mode interface, uint8_t xgAddr, uint8_t mAddr)
+{
+    settings.device.commInterface = interface;
+    settings.device.agAddress = xgAddr;
+    settings.device.mAddress = mAddr;
+
+    settings.gyro.enabled = true;
+    settings.gyro.enableX = true;
+    settings.gyro.enableY = true;
+    settings.gyro.enableZ = true;
+    // gyro scale can be 245, 500, or 2000
+    settings.gyro.scale = 245;
+    // gyro sample rate: value between 1-6
+    // 1 = 14.9    4 = 238
+    // 2 = 59.5    5 = 476
+    // 3 = 119     6 = 952
+    settings.gyro.sampleRate = 6;
+    // gyro cutoff frequency: value between 0-3
+    // Actual value of cutoff frequency depends
+    // on sample rate.
+    settings.gyro.bandwidth = 0;
+    settings.gyro.lowPowerEnable = false;
+    settings.gyro.HPFEnable = false;
+    // Gyro HPF cutoff frequency: value between 0-9
+    // Actual value depends on sample rate. Only applies
+    // if gyroHPFEnable is true.
+    settings.gyro.HPFCutoff = 0;
+    settings.gyro.flipX = false;
+    settings.gyro.flipY = false;
+    settings.gyro.flipZ = false;
+    settings.gyro.orientation = 0;
+    settings.gyro.latchInterrupt = true;
+
+    settings.accel.enabled = true;
+    settings.accel.enableX = true;
+    settings.accel.enableY = true;
+    settings.accel.enableZ = true;
+    // accel scale can be 2, 4, 8, or 16
+    settings.accel.scale = 2;
+    // accel sample rate can be 1-6
+    // 1 = 10 Hz    4 = 238 Hz
+    // 2 = 50 Hz    5 = 476 Hz
+    // 3 = 119 Hz   6 = 952 Hz
+    settings.accel.sampleRate = 6;
+    // Accel cutoff freqeuncy can be any value between -1 - 3. 
+    // -1 = bandwidth determined by sample rate
+    // 0 = 408 Hz   2 = 105 Hz
+    // 1 = 211 Hz   3 = 50 Hz
+    settings.accel.bandwidth = -1;
+    settings.accel.highResEnable = false;
+    // accelHighResBandwidth can be any value between 0-3
+    // LP cutoff is set to a factor of sample rate
+    // 0 = ODR/50    2 = ODR/9
+    // 1 = ODR/100   3 = ODR/400
+    settings.accel.highResBandwidth = 0;
+
+    settings.mag.enabled = true;
+    // mag scale can be 4, 8, 12, or 16
+    settings.mag.scale = 4;
+    // mag data rate can be 0-7
+    // 0 = 0.625 Hz  4 = 10 Hz
+    // 1 = 1.25 Hz   5 = 20 Hz
+    // 2 = 2.5 Hz    6 = 40 Hz
+    // 3 = 5 Hz      7 = 80 Hz
+    settings.mag.sampleRate = 7;
+    settings.mag.tempCompensationEnable = false;
+    // magPerformance can be any value between 0-3
+    // 0 = Low power mode      2 = high performance
+    // 1 = medium performance  3 = ultra-high performance
+    settings.mag.XYPerformance = 3;
+    settings.mag.ZPerformance = 3;
+    settings.mag.lowPowerEnable = false;
+    // magOperatingMode can be 0-2
+    // 0 = continuous conversion
+    // 1 = single-conversion
+    // 2 = power down
+    settings.mag.operatingMode = 0;
+
+    settings.temp.enabled = true;
+    for (int i=0; i<3; i++)
+    {
+        gBias[i] = 0;
+        aBias[i] = 0;
+        mBias[i] = 0;
+        gBiasRaw[i] = 0;
+        aBiasRaw[i] = 0;
+        mBiasRaw[i] = 0;
+    }
+    _autoCalc = false;
+}
+
+
+uint16_t LSM9DS1::begin()
+{
+    //! Todo: don't use _xgAddress or _mAddress, duplicating memory
+    _xgAddress = settings.device.agAddress;
+    _mAddress = settings.device.mAddress;
+    
+    constrainScales();
+    // Once we have the scale values, we can calculate the resolution
+    // of each sensor. That's what these functions are for. One for each sensor
+    calcgRes(); // Calculate DPS / ADC tick, stored in gRes variable
+    calcmRes(); // Calculate Gs / ADC tick, stored in mRes variable
+    calcaRes(); // Calculate g / ADC tick, stored in aRes variable
+    
+    // Now, initialize our hardware interface.
+    if (settings.device.commInterface == IMU_MODE_I2C)  // If we're using I2C
+        initI2C();  // Initialize I2C
+    else if (settings.device.commInterface == IMU_MODE_SPI)     // else, if we're using SPI
+        initSPI();  // Initialize SPI
+        
+    // To verify communication, we can read from the WHO_AM_I register of
+    // each device. Store those in a variable so we can return them.
+    uint8_t mTest = mReadByte(WHO_AM_I_M);      // Read the gyro WHO_AM_I
+    uint8_t xgTest = xgReadByte(WHO_AM_I_XG);   // Read the accel/mag WHO_AM_I
+    pc.printf("%x, %x, %x, %x\n\r", mTest, xgTest, _xgAddress, _mAddress);
+    uint16_t whoAmICombined = (xgTest << 8) | mTest;
+    
+    if (whoAmICombined != ((WHO_AM_I_AG_RSP << 8) | WHO_AM_I_M_RSP))
+        return 0;
+    
+    // Gyro initialization stuff:
+    initGyro(); // This will "turn on" the gyro. Setting up interrupts, etc.
+    
+    // Accelerometer initialization stuff:
+    initAccel(); // "Turn on" all axes of the accel. Set up interrupts, etc.
+    
+    // Magnetometer initialization stuff:
+    initMag(); // "Turn on" all axes of the mag. Set up interrupts, etc.
+
+    // Once everything is initialized, return the WHO_AM_I registers we read:
+    return whoAmICombined;
+}
+
+void LSM9DS1::initGyro()
+{
+    uint8_t tempRegValue = 0;
+    
+    // CTRL_REG1_G (Default value: 0x00)
+    // [ODR_G2][ODR_G1][ODR_G0][FS_G1][FS_G0][0][BW_G1][BW_G0]
+    // ODR_G[2:0] - Output data rate selection
+    // FS_G[1:0] - Gyroscope full-scale selection
+    // BW_G[1:0] - Gyroscope bandwidth selection
+    
+    // To disable gyro, set sample rate bits to 0. We'll only set sample
+    // rate if the gyro is enabled.
+    if (settings.gyro.enabled)
+    {
+        tempRegValue = (settings.gyro.sampleRate & 0x07) << 5;
+    }
+    switch (settings.gyro.scale)
+    {
+        case 500:
+            tempRegValue |= (0x1 << 3);
+            break;
+        case 2000:
+            tempRegValue |= (0x3 << 3);
+            break;
+        // Otherwise we'll set it to 245 dps (0x0 << 4)
+    }
+    tempRegValue |= (settings.gyro.bandwidth & 0x3);
+    xgWriteByte(CTRL_REG1_G, tempRegValue);
+    
+    // CTRL_REG2_G (Default value: 0x00)
+    // [0][0][0][0][INT_SEL1][INT_SEL0][OUT_SEL1][OUT_SEL0]
+    // INT_SEL[1:0] - INT selection configuration
+    // OUT_SEL[1:0] - Out selection configuration
+    xgWriteByte(CTRL_REG2_G, 0x00); 
+    
+    // CTRL_REG3_G (Default value: 0x00)
+    // [LP_mode][HP_EN][0][0][HPCF3_G][HPCF2_G][HPCF1_G][HPCF0_G]
+    // LP_mode - Low-power mode enable (0: disabled, 1: enabled)
+    // HP_EN - HPF enable (0:disabled, 1: enabled)
+    // HPCF_G[3:0] - HPF cutoff frequency
+    tempRegValue = settings.gyro.lowPowerEnable ? (1<<7) : 0;
+    if (settings.gyro.HPFEnable)
+    {
+        tempRegValue |= (1<<6) | (settings.gyro.HPFCutoff & 0x0F);
+    }
+    xgWriteByte(CTRL_REG3_G, tempRegValue);
+    
+    // CTRL_REG4 (Default value: 0x38)
+    // [0][0][Zen_G][Yen_G][Xen_G][0][LIR_XL1][4D_XL1]
+    // Zen_G - Z-axis output enable (0:disable, 1:enable)
+    // Yen_G - Y-axis output enable (0:disable, 1:enable)
+    // Xen_G - X-axis output enable (0:disable, 1:enable)
+    // LIR_XL1 - Latched interrupt (0:not latched, 1:latched)
+    // 4D_XL1 - 4D option on interrupt (0:6D used, 1:4D used)
+    tempRegValue = 0;
+    if (settings.gyro.enableZ) tempRegValue |= (1<<5);
+    if (settings.gyro.enableY) tempRegValue |= (1<<4);
+    if (settings.gyro.enableX) tempRegValue |= (1<<3);
+    if (settings.gyro.latchInterrupt) tempRegValue |= (1<<1);
+    xgWriteByte(CTRL_REG4, tempRegValue);
+    
+    // ORIENT_CFG_G (Default value: 0x00)
+    // [0][0][SignX_G][SignY_G][SignZ_G][Orient_2][Orient_1][Orient_0]
+    // SignX_G - Pitch axis (X) angular rate sign (0: positive, 1: negative)
+    // Orient [2:0] - Directional user orientation selection
+    tempRegValue = 0;
+    if (settings.gyro.flipX) tempRegValue |= (1<<5);
+    if (settings.gyro.flipY) tempRegValue |= (1<<4);
+    if (settings.gyro.flipZ) tempRegValue |= (1<<3);
+    xgWriteByte(ORIENT_CFG_G, tempRegValue);
+}
+
+void LSM9DS1::initAccel()
+{
+    uint8_t tempRegValue = 0;
+    
+    //  CTRL_REG5_XL (0x1F) (Default value: 0x38)
+    //  [DEC_1][DEC_0][Zen_XL][Yen_XL][Zen_XL][0][0][0]
+    //  DEC[0:1] - Decimation of accel data on OUT REG and FIFO.
+    //      00: None, 01: 2 samples, 10: 4 samples 11: 8 samples
+    //  Zen_XL - Z-axis output enabled
+    //  Yen_XL - Y-axis output enabled
+    //  Xen_XL - X-axis output enabled
+    if (settings.accel.enableZ) tempRegValue |= (1<<5);
+    if (settings.accel.enableY) tempRegValue |= (1<<4);
+    if (settings.accel.enableX) tempRegValue |= (1<<3);
+    
+    xgWriteByte(CTRL_REG5_XL, tempRegValue);
+    
+    // CTRL_REG6_XL (0x20) (Default value: 0x00)
+    // [ODR_XL2][ODR_XL1][ODR_XL0][FS1_XL][FS0_XL][BW_SCAL_ODR][BW_XL1][BW_XL0]
+    // ODR_XL[2:0] - Output data rate & power mode selection
+    // FS_XL[1:0] - Full-scale selection
+    // BW_SCAL_ODR - Bandwidth selection
+    // BW_XL[1:0] - Anti-aliasing filter bandwidth selection
+    tempRegValue = 0;
+    // To disable the accel, set the sampleRate bits to 0.
+    if (settings.accel.enabled)
+    {
+        tempRegValue |= (settings.accel.sampleRate & 0x07) << 5;
+    }
+    switch (settings.accel.scale)
+    {
+        case 4:
+            tempRegValue |= (0x2 << 3);
+            break;
+        case 8:
+            tempRegValue |= (0x3 << 3);
+            break;
+        case 16:
+            tempRegValue |= (0x1 << 3);
+            break;
+        // Otherwise it'll be set to 2g (0x0 << 3)
+    }
+    if (settings.accel.bandwidth >= 0)
+    {
+        tempRegValue |= (1<<2); // Set BW_SCAL_ODR
+        tempRegValue |= (settings.accel.bandwidth & 0x03);
+    }
+    xgWriteByte(CTRL_REG6_XL, tempRegValue);
+    
+    // CTRL_REG7_XL (0x21) (Default value: 0x00)
+    // [HR][DCF1][DCF0][0][0][FDS][0][HPIS1]
+    // HR - High resolution mode (0: disable, 1: enable)
+    // DCF[1:0] - Digital filter cutoff frequency
+    // FDS - Filtered data selection
+    // HPIS1 - HPF enabled for interrupt function
+    tempRegValue = 0;
+    if (settings.accel.highResEnable)
+    {
+        tempRegValue |= (1<<7); // Set HR bit
+        tempRegValue |= (settings.accel.highResBandwidth & 0x3) << 5;
+    }
+    xgWriteByte(CTRL_REG7_XL, tempRegValue);
+}
+
+// This is a function that uses the FIFO to accumulate sample of accelerometer and gyro data, average
+// them, scales them to  gs and deg/s, respectively, and then passes the biases to the main sketch
+// for subtraction from all subsequent data. There are no gyro and accelerometer bias registers to store
+// the data as there are in the ADXL345, a precursor to the LSM9DS0, or the MPU-9150, so we have to
+// subtract the biases ourselves. This results in a more accurate measurement in general and can
+// remove errors due to imprecise or varying initial placement. Calibration of sensor data in this manner
+// is good practice.
+void LSM9DS1::calibrate(bool autoCalc)
+{  
+    uint8_t data[6] = {0, 0, 0, 0, 0, 0};
+    uint8_t samples = 0;
+    int ii;
+    int32_t aBiasRawTemp[3] = {0, 0, 0};
+    int32_t gBiasRawTemp[3] = {0, 0, 0};
+    
+    // Turn on FIFO and set threshold to 32 samples
+    enableFIFO(true);
+    setFIFO(FIFO_THS, 0x1F);
+    while (samples < 0x1F)
+    {
+        samples = (xgReadByte(FIFO_SRC) & 0x3F); // Read number of stored samples
+    }
+    for(ii = 0; ii < samples ; ii++) 
+    {   // Read the gyro data stored in the FIFO
+        readGyro();
+        gBiasRawTemp[0] += gx;
+        gBiasRawTemp[1] += gy;
+        gBiasRawTemp[2] += gz;
+        readAccel();
+        aBiasRawTemp[0] += ax;
+        aBiasRawTemp[1] += ay;
+        aBiasRawTemp[2] += az - (int16_t)(1./aRes); // Assumes sensor facing up!
+    }  
+    for (ii = 0; ii < 3; ii++)
+    {
+        gBiasRaw[ii] = gBiasRawTemp[ii] / samples;
+        gBias[ii] = calcGyro(gBiasRaw[ii]);
+        aBiasRaw[ii] = aBiasRawTemp[ii] / samples;
+        aBias[ii] = calcAccel(aBiasRaw[ii]);
+    }
+    
+    enableFIFO(false);
+    setFIFO(FIFO_OFF, 0x00);
+    
+    if (autoCalc) _autoCalc = true;
+}
+
+void LSM9DS1::calibrateMag(bool loadIn)
+{
+    int i, j;
+    int16_t magMin[3] = {0, 0, 0};
+    int16_t magMax[3] = {0, 0, 0}; // The road warrior
+    
+    for (i=0; i<128; i++)
+    {
+        while (!magAvailable())
+            ;
+        readMag();
+        int16_t magTemp[3] = {0, 0, 0};
+        magTemp[0] = mx;        
+        magTemp[1] = my;
+        magTemp[2] = mz;
+        for (j = 0; j < 3; j++)
+        {
+            if (magTemp[j] > magMax[j]) magMax[j] = magTemp[j];
+            if (magTemp[j] < magMin[j]) magMin[j] = magTemp[j];
+        }
+    }
+    for (j = 0; j < 3; j++)
+    {
+        mBiasRaw[j] = (magMax[j] + magMin[j]) / 2;
+        mBias[j] = calcMag(mBiasRaw[j]);
+        if (loadIn)
+            magOffset(j, mBiasRaw[j]);
+    }
+    
+}
+void LSM9DS1::magOffset(uint8_t axis, int16_t offset)
+{
+    if (axis > 2)
+        return;
+    uint8_t msb, lsb;
+    msb = (offset & 0xFF00) >> 8;
+    lsb = offset & 0x00FF;
+    mWriteByte(OFFSET_X_REG_L_M + (2 * axis), lsb);
+    mWriteByte(OFFSET_X_REG_H_M + (2 * axis), msb);
+}
+
+void LSM9DS1::initMag()
+{
+    uint8_t tempRegValue = 0;
+    
+    // CTRL_REG1_M (Default value: 0x10)
+    // [TEMP_COMP][OM1][OM0][DO2][DO1][DO0][0][ST]
+    // TEMP_COMP - Temperature compensation
+    // OM[1:0] - X & Y axes op mode selection
+    //  00:low-power, 01:medium performance
+    //  10: high performance, 11:ultra-high performance
+    // DO[2:0] - Output data rate selection
+    // ST - Self-test enable
+    if (settings.mag.tempCompensationEnable) tempRegValue |= (1<<7);
+    tempRegValue |= (settings.mag.XYPerformance & 0x3) << 5;
+    tempRegValue |= (settings.mag.sampleRate & 0x7) << 2;
+    mWriteByte(CTRL_REG1_M, tempRegValue);
+    
+    // CTRL_REG2_M (Default value 0x00)
+    // [0][FS1][FS0][0][REBOOT][SOFT_RST][0][0]
+    // FS[1:0] - Full-scale configuration
+    // REBOOT - Reboot memory content (0:normal, 1:reboot)
+    // SOFT_RST - Reset config and user registers (0:default, 1:reset)
+    tempRegValue = 0;
+    switch (settings.mag.scale)
+    {
+    case 8:
+        tempRegValue |= (0x1 << 5);
+        break;
+    case 12:
+        tempRegValue |= (0x2 << 5);
+        break;
+    case 16:
+        tempRegValue |= (0x3 << 5);
+        break;
+    // Otherwise we'll default to 4 gauss (00)
+    }
+    mWriteByte(CTRL_REG2_M, tempRegValue); // +/-4Gauss
+    
+    // CTRL_REG3_M (Default value: 0x03)
+    // [I2C_DISABLE][0][LP][0][0][SIM][MD1][MD0]
+    // I2C_DISABLE - Disable I2C interace (0:enable, 1:disable)
+    // LP - Low-power mode cofiguration (1:enable)
+    // SIM - SPI mode selection (0:write-only, 1:read/write enable)
+    // MD[1:0] - Operating mode
+    //  00:continuous conversion, 01:single-conversion,
+    //  10,11: Power-down
+    tempRegValue = 0;
+    if (settings.mag.lowPowerEnable) tempRegValue |= (1<<5);
+    tempRegValue |= (settings.mag.operatingMode & 0x3);
+    mWriteByte(CTRL_REG3_M, tempRegValue); // Continuous conversion mode
+    
+    // CTRL_REG4_M (Default value: 0x00)
+    // [0][0][0][0][OMZ1][OMZ0][BLE][0]
+    // OMZ[1:0] - Z-axis operative mode selection
+    //  00:low-power mode, 01:medium performance
+    //  10:high performance, 10:ultra-high performance
+    // BLE - Big/little endian data
+    tempRegValue = 0;
+    tempRegValue = (settings.mag.ZPerformance & 0x3) << 2;
+    mWriteByte(CTRL_REG4_M, tempRegValue);
+    
+    // CTRL_REG5_M (Default value: 0x00)
+    // [0][BDU][0][0][0][0][0][0]
+    // BDU - Block data update for magnetic data
+    //  0:continuous, 1:not updated until MSB/LSB are read
+    tempRegValue = 0;
+    mWriteByte(CTRL_REG5_M, tempRegValue);
+}
+
+uint8_t LSM9DS1::accelAvailable()
+{
+    uint8_t status = xgReadByte(STATUS_REG_1);
+    
+    return (status & (1<<0));
+}
+
+uint8_t LSM9DS1::gyroAvailable()
+{
+    uint8_t status = xgReadByte(STATUS_REG_1);
+    
+    return ((status & (1<<1)) >> 1);
+}
+
+uint8_t LSM9DS1::tempAvailable()
+{
+    uint8_t status = xgReadByte(STATUS_REG_1);
+    
+    return ((status & (1<<2)) >> 2);
+}
+
+uint8_t LSM9DS1::magAvailable(lsm9ds1_axis axis)
+{
+    uint8_t status;
+    status = mReadByte(STATUS_REG_M);
+    
+    return ((status & (1<<axis)) >> axis);
+}
+
+void LSM9DS1::readAccel()
+{
+    uint8_t temp[6]; // We'll read six bytes from the accelerometer into temp   
+    xgReadBytes(OUT_X_L_XL, temp, 6); // Read 6 bytes, beginning at OUT_X_L_XL
+    ax = (temp[1] << 8) | temp[0]; // Store x-axis values into ax
+    ay = (temp[3] << 8) | temp[2]; // Store y-axis values into ay
+    az = (temp[5] << 8) | temp[4]; // Store z-axis values into az
+    if (_autoCalc)
+    {
+        ax -= aBiasRaw[X_AXIS];
+        ay -= aBiasRaw[Y_AXIS];
+        az -= aBiasRaw[Z_AXIS];
+    }
+}
+
+int16_t LSM9DS1::readAccel(lsm9ds1_axis axis)
+{
+    uint8_t temp[2];
+    int16_t value;
+    xgReadBytes(OUT_X_L_XL + (2 * axis), temp, 2);
+    value = (temp[1] << 8) | temp[0];
+    
+    if (_autoCalc)
+        value -= aBiasRaw[axis];
+    
+    return value;
+}
+
+void LSM9DS1::readMag()
+{
+    uint8_t temp[6]; // We'll read six bytes from the mag into temp 
+    mReadBytes(OUT_X_L_M, temp, 6); // Read 6 bytes, beginning at OUT_X_L_M
+    mx = (temp[1] << 8) | temp[0]; // Store x-axis values into mx
+    my = (temp[3] << 8) | temp[2]; // Store y-axis values into my
+    mz = (temp[5] << 8) | temp[4]; // Store z-axis values into mz
+}
+
+int16_t LSM9DS1::readMag(lsm9ds1_axis axis)
+{
+    uint8_t temp[2];
+    mReadBytes(OUT_X_L_M + (2 * axis), temp, 2);
+    return (temp[1] << 8) | temp[0];
+}
+
+void LSM9DS1::readTemp()
+{
+    uint8_t temp[2]; // We'll read two bytes from the temperature sensor into temp  
+    xgReadBytes(OUT_TEMP_L, temp, 2); // Read 2 bytes, beginning at OUT_TEMP_L
+    temperature = ((int16_t)temp[1] << 8) | temp[0];
+}
+
+void LSM9DS1::readGyro()
+{
+    uint8_t temp[6]; // We'll read six bytes from the gyro into temp
+    xgReadBytes(OUT_X_L_G, temp, 6); // Read 6 bytes, beginning at OUT_X_L_G
+    gx = (temp[1] << 8) | temp[0]; // Store x-axis values into gx
+    gy = (temp[3] << 8) | temp[2]; // Store y-axis values into gy
+    gz = (temp[5] << 8) | temp[4]; // Store z-axis values into gz
+    if (_autoCalc)
+    {
+        gx -= gBiasRaw[X_AXIS];
+        gy -= gBiasRaw[Y_AXIS];
+        gz -= gBiasRaw[Z_AXIS];
+    }
+}
+
+int16_t LSM9DS1::readGyro(lsm9ds1_axis axis)
+{
+    uint8_t temp[2];
+    int16_t value;
+    
+    xgReadBytes(OUT_X_L_G + (2 * axis), temp, 2);
+    
+    value = (temp[1] << 8) | temp[0];
+    
+    if (_autoCalc)
+        value -= gBiasRaw[axis];
+    
+    return value;
+}
+
+float LSM9DS1::calcGyro(int16_t gyro)
+{
+    // Return the gyro raw reading times our pre-calculated DPS / (ADC tick):
+    return gRes * gyro; 
+}
+
+float LSM9DS1::calcAccel(int16_t accel)
+{
+    // Return the accel raw reading times our pre-calculated g's / (ADC tick):
+    return aRes * accel;
+}
+
+float LSM9DS1::calcMag(int16_t mag)
+{
+    // Return the mag raw reading times our pre-calculated Gs / (ADC tick):
+    return mRes * mag;
+}
+
+void LSM9DS1::setGyroScale(uint16_t gScl)
+{
+    // Read current value of CTRL_REG1_G:
+    uint8_t ctrl1RegValue = xgReadByte(CTRL_REG1_G);
+    // Mask out scale bits (3 & 4):
+    ctrl1RegValue &= 0xE7;
+    switch (gScl)
+    {
+        case 500:
+            ctrl1RegValue |= (0x1 << 3);
+            settings.gyro.scale = 500;
+            break;
+        case 2000:
+            ctrl1RegValue |= (0x3 << 3);
+            settings.gyro.scale = 2000;
+            break;
+        default: // Otherwise we'll set it to 245 dps (0x0 << 4)
+            settings.gyro.scale = 245;
+            break;
+    }
+    xgWriteByte(CTRL_REG1_G, ctrl1RegValue);
+    
+    calcgRes(); 
+}
+
+void LSM9DS1::setAccelScale(uint8_t aScl)
+{
+    // We need to preserve the other bytes in CTRL_REG6_XL. So, first read it:
+    uint8_t tempRegValue = xgReadByte(CTRL_REG6_XL);
+    // Mask out accel scale bits:
+    tempRegValue &= 0xE7;
+    
+    switch (aScl)
+    {
+        case 4:
+            tempRegValue |= (0x2 << 3);
+            settings.accel.scale = 4;
+            break;
+        case 8:
+            tempRegValue |= (0x3 << 3);
+            settings.accel.scale = 8;
+            break;
+        case 16:
+            tempRegValue |= (0x1 << 3);
+            settings.accel.scale = 16;
+            break;
+        default: // Otherwise it'll be set to 2g (0x0 << 3)
+            settings.accel.scale = 2;
+            break;
+    }
+    xgWriteByte(CTRL_REG6_XL, tempRegValue);
+    
+    // Then calculate a new aRes, which relies on aScale being set correctly:
+    calcaRes();
+}
+
+void LSM9DS1::setMagScale(uint8_t mScl)
+{
+    // We need to preserve the other bytes in CTRL_REG6_XM. So, first read it:
+    uint8_t temp = mReadByte(CTRL_REG2_M);
+    // Then mask out the mag scale bits:
+    temp &= 0xFF^(0x3 << 5);
+    
+    switch (mScl)
+    {
+    case 8:
+        temp |= (0x1 << 5);
+        settings.mag.scale = 8;
+        break;
+    case 12:
+        temp |= (0x2 << 5);
+        settings.mag.scale = 12;
+        break;
+    case 16:
+        temp |= (0x3 << 5);
+        settings.mag.scale = 16;
+        break;
+    default: // Otherwise we'll default to 4 gauss (00)
+        settings.mag.scale = 4;
+        break;
+    }   
+    
+    // And write the new register value back into CTRL_REG6_XM:
+    mWriteByte(CTRL_REG2_M, temp);
+    
+    // We've updated the sensor, but we also need to update our class variables
+    // First update mScale:
+    //mScale = mScl;
+    // Then calculate a new mRes, which relies on mScale being set correctly:
+    calcmRes();
+}
+
+void LSM9DS1::setGyroODR(uint8_t gRate)
+{
+    // Only do this if gRate is not 0 (which would disable the gyro)
+    if ((gRate & 0x07) != 0)
+    {
+        // We need to preserve the other bytes in CTRL_REG1_G. So, first read it:
+        uint8_t temp = xgReadByte(CTRL_REG1_G);
+        // Then mask out the gyro ODR bits:
+        temp &= 0xFF^(0x7 << 5);
+        temp |= (gRate & 0x07) << 5;
+        // Update our settings struct
+        settings.gyro.sampleRate = gRate & 0x07;
+        // And write the new register value back into CTRL_REG1_G:
+        xgWriteByte(CTRL_REG1_G, temp);
+    }
+}
+
+void LSM9DS1::setAccelODR(uint8_t aRate)
+{
+    // Only do this if aRate is not 0 (which would disable the accel)
+    if ((aRate & 0x07) != 0)
+    {
+        // We need to preserve the other bytes in CTRL_REG1_XM. So, first read it:
+        uint8_t temp = xgReadByte(CTRL_REG6_XL);
+        // Then mask out the accel ODR bits:
+        temp &= 0x1F;
+        // Then shift in our new ODR bits:
+        temp |= ((aRate & 0x07) << 5);
+        settings.accel.sampleRate = aRate & 0x07;
+        // And write the new register value back into CTRL_REG1_XM:
+        xgWriteByte(CTRL_REG6_XL, temp);
+    }
+}
+
+void LSM9DS1::setMagODR(uint8_t mRate)
+{
+    // We need to preserve the other bytes in CTRL_REG5_XM. So, first read it:
+    uint8_t temp = mReadByte(CTRL_REG1_M);
+    // Then mask out the mag ODR bits:
+    temp &= 0xFF^(0x7 << 2);
+    // Then shift in our new ODR bits:
+    temp |= ((mRate & 0x07) << 2);
+    settings.mag.sampleRate = mRate & 0x07;
+    // And write the new register value back into CTRL_REG5_XM:
+    mWriteByte(CTRL_REG1_M, temp);
+}
+
+void LSM9DS1::calcgRes()
+{
+    gRes = ((float) settings.gyro.scale) / 32768.0;
+}
+
+void LSM9DS1::calcaRes()
+{
+    aRes = ((float) settings.accel.scale) / 32768.0;
+}
+
+void LSM9DS1::calcmRes()
+{
+    //mRes = ((float) settings.mag.scale) / 32768.0;
+    switch (settings.mag.scale)
+    {
+    case 4:
+        mRes = magSensitivity[0];
+        break;
+    case 8:
+        mRes = magSensitivity[1];
+        break;
+    case 12:
+        mRes = magSensitivity[2];
+        break;
+    case 16:
+        mRes = magSensitivity[3];
+        break;
+    }
+    
+}
+
+void LSM9DS1::configInt(interrupt_select interrupt, uint8_t generator,
+                         h_lactive activeLow, pp_od pushPull)
+{
+    // Write to INT1_CTRL or INT2_CTRL. [interupt] should already be one of
+    // those two values.
+    // [generator] should be an OR'd list of values from the interrupt_generators enum
+    xgWriteByte(interrupt, generator);
+    
+    // Configure CTRL_REG8
+    uint8_t temp;
+    temp = xgReadByte(CTRL_REG8);
+    
+    if (activeLow) temp |= (1<<5);
+    else temp &= ~(1<<5);
+    
+    if (pushPull) temp &= ~(1<<4);
+    else temp |= (1<<4);
+    
+    xgWriteByte(CTRL_REG8, temp);
+}
+
+void LSM9DS1::configInactivity(uint8_t duration, uint8_t threshold, bool sleepOn)
+{
+    uint8_t temp = 0;
+    
+    temp = threshold & 0x7F;
+    if (sleepOn) temp |= (1<<7);
+    xgWriteByte(ACT_THS, temp);
+    
+    xgWriteByte(ACT_DUR, duration);
+}
+
+uint8_t LSM9DS1::getInactivity()
+{
+    uint8_t temp = xgReadByte(STATUS_REG_0);
+    temp &= (0x10);
+    return temp;
+}
+
+void LSM9DS1::configAccelInt(uint8_t generator, bool andInterrupts)
+{
+    // Use variables from accel_interrupt_generator, OR'd together to create
+    // the [generator]value.
+    uint8_t temp = generator;
+    if (andInterrupts) temp |= 0x80;
+    xgWriteByte(INT_GEN_CFG_XL, temp);
+}
+
+void LSM9DS1::configAccelThs(uint8_t threshold, lsm9ds1_axis axis, uint8_t duration, bool wait)
+{
+    // Write threshold value to INT_GEN_THS_?_XL.
+    // axis will be 0, 1, or 2 (x, y, z respectively)
+    xgWriteByte(INT_GEN_THS_X_XL + axis, threshold);
+    
+    // Write duration and wait to INT_GEN_DUR_XL
+    uint8_t temp;
+    temp = (duration & 0x7F);
+    if (wait) temp |= 0x80;
+    xgWriteByte(INT_GEN_DUR_XL, temp);
+}
+
+uint8_t LSM9DS1::getAccelIntSrc()
+{
+    uint8_t intSrc = xgReadByte(INT_GEN_SRC_XL);
+    
+    // Check if the IA_XL (interrupt active) bit is set
+    if (intSrc & (1<<6))
+    {
+        return (intSrc & 0x3F);
+    }
+    
+    return 0;
+}
+
+void LSM9DS1::configGyroInt(uint8_t generator, bool aoi, bool latch)
+{
+    // Use variables from accel_interrupt_generator, OR'd together to create
+    // the [generator]value.
+    uint8_t temp = generator;
+    if (aoi) temp |= 0x80;
+    if (latch) temp |= 0x40;
+    xgWriteByte(INT_GEN_CFG_G, temp);
+}
+
+void LSM9DS1::configGyroThs(int16_t threshold, lsm9ds1_axis axis, uint8_t duration, bool wait)
+{
+    uint8_t buffer[2];
+    buffer[0] = (threshold & 0x7F00) >> 8;
+    buffer[1] = (threshold & 0x00FF);
+    // Write threshold value to INT_GEN_THS_?H_G and  INT_GEN_THS_?L_G.
+    // axis will be 0, 1, or 2 (x, y, z respectively)
+    xgWriteByte(INT_GEN_THS_XH_G + (axis * 2), buffer[0]);
+    xgWriteByte(INT_GEN_THS_XH_G + 1 + (axis * 2), buffer[1]);
+    
+    // Write duration and wait to INT_GEN_DUR_XL
+    uint8_t temp;
+    temp = (duration & 0x7F);
+    if (wait) temp |= 0x80;
+    xgWriteByte(INT_GEN_DUR_G, temp);
+}
+
+uint8_t LSM9DS1::getGyroIntSrc()
+{
+    uint8_t intSrc = xgReadByte(INT_GEN_SRC_G);
+    
+    // Check if the IA_G (interrupt active) bit is set
+    if (intSrc & (1<<6))
+    {
+        return (intSrc & 0x3F);
+    }
+    
+    return 0;
+}
+
+void LSM9DS1::configMagInt(uint8_t generator, h_lactive activeLow, bool latch)
+{
+    // Mask out non-generator bits (0-4)
+    uint8_t config = (generator & 0xE0);    
+    // IEA bit is 0 for active-low, 1 for active-high.
+    if (activeLow == INT_ACTIVE_HIGH) config |= (1<<2);
+    // IEL bit is 0 for latched, 1 for not-latched
+    if (!latch) config |= (1<<1);
+    // As long as we have at least 1 generator, enable the interrupt
+    if (generator != 0) config |= (1<<0);
+    
+    mWriteByte(INT_CFG_M, config);
+}
+
+void LSM9DS1::configMagThs(uint16_t threshold)
+{
+    // Write high eight bits of [threshold] to INT_THS_H_M
+    mWriteByte(INT_THS_H_M, uint8_t((threshold & 0x7F00) >> 8));
+    // Write low eight bits of [threshold] to INT_THS_L_M
+    mWriteByte(INT_THS_L_M, uint8_t(threshold & 0x00FF));
+}
+
+uint8_t LSM9DS1::getMagIntSrc()
+{
+    uint8_t intSrc = mReadByte(INT_SRC_M);
+    
+    // Check if the INT (interrupt active) bit is set
+    if (intSrc & (1<<0))
+    {
+        return (intSrc & 0xFE);
+    }
+    
+    return 0;
+}
+
+void LSM9DS1::sleepGyro(bool enable)
+{
+    uint8_t temp = xgReadByte(CTRL_REG9);
+    if (enable) temp |= (1<<6);
+    else temp &= ~(1<<6);
+    xgWriteByte(CTRL_REG9, temp);
+}
+
+void LSM9DS1::enableFIFO(bool enable)
+{
+    uint8_t temp = xgReadByte(CTRL_REG9);
+    if (enable) temp |= (1<<1);
+    else temp &= ~(1<<1);
+    xgWriteByte(CTRL_REG9, temp);
+}
+
+void LSM9DS1::setFIFO(fifoMode_type fifoMode, uint8_t fifoThs)
+{
+    // Limit threshold - 0x1F (31) is the maximum. If more than that was asked
+    // limit it to the maximum.
+    uint8_t threshold = fifoThs <= 0x1F ? fifoThs : 0x1F;
+    xgWriteByte(FIFO_CTRL, ((fifoMode & 0x7) << 5) | (threshold & 0x1F));
+}
+
+uint8_t LSM9DS1::getFIFOSamples()
+{
+    return (xgReadByte(FIFO_SRC) & 0x3F);
+}
+
+void LSM9DS1::constrainScales()
+{
+    if ((settings.gyro.scale != 245) && (settings.gyro.scale != 500) && 
+        (settings.gyro.scale != 2000))
+    {
+        settings.gyro.scale = 245;
+    }
+        
+    if ((settings.accel.scale != 2) && (settings.accel.scale != 4) &&
+        (settings.accel.scale != 8) && (settings.accel.scale != 16))
+    {
+        settings.accel.scale = 2;
+    }
+        
+    if ((settings.mag.scale != 4) && (settings.mag.scale != 8) &&
+        (settings.mag.scale != 12) && (settings.mag.scale != 16))
+    {
+        settings.mag.scale = 4;
+    }
+}
+
+void LSM9DS1::xgWriteByte(uint8_t subAddress, uint8_t data)
+{
+    // Whether we're using I2C or SPI, write a byte using the
+    // gyro-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C) {
+        printf("yo");
+        I2CwriteByte(_xgAddress, subAddress, data);
+    } else if (settings.device.commInterface == IMU_MODE_SPI) {
+        SPIwriteByte(_xgAddress, subAddress, data);
+    }
+}
+
+void LSM9DS1::mWriteByte(uint8_t subAddress, uint8_t data)
+{
+    // Whether we're using I2C or SPI, write a byte using the
+    // accelerometer-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C)
+        return I2CwriteByte(_mAddress, subAddress, data);
+    else if (settings.device.commInterface == IMU_MODE_SPI)
+        return SPIwriteByte(_mAddress, subAddress, data);
+}
+
+uint8_t LSM9DS1::xgReadByte(uint8_t subAddress)
+{
+    // Whether we're using I2C or SPI, read a byte using the
+    // gyro-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C)
+        return I2CreadByte(_xgAddress, subAddress);
+    else if (settings.device.commInterface == IMU_MODE_SPI)
+        return SPIreadByte(_xgAddress, subAddress);
+}
+
+void LSM9DS1::xgReadBytes(uint8_t subAddress, uint8_t * dest, uint8_t count)
+{
+    // Whether we're using I2C or SPI, read multiple bytes using the
+    // gyro-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C) {
+        I2CreadBytes(_xgAddress, subAddress, dest, count);
+    } else if (settings.device.commInterface == IMU_MODE_SPI) {
+        SPIreadBytes(_xgAddress, subAddress, dest, count);
+    }
+}
+
+uint8_t LSM9DS1::mReadByte(uint8_t subAddress)
+{
+    // Whether we're using I2C or SPI, read a byte using the
+    // accelerometer-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C)
+        return I2CreadByte(_mAddress, subAddress);
+    else if (settings.device.commInterface == IMU_MODE_SPI)
+        return SPIreadByte(_mAddress, subAddress);
+}
+
+void LSM9DS1::mReadBytes(uint8_t subAddress, uint8_t * dest, uint8_t count)
+{
+    // Whether we're using I2C or SPI, read multiple bytes using the
+    // accelerometer-specific I2C address or SPI CS pin.
+    if (settings.device.commInterface == IMU_MODE_I2C)
+        I2CreadBytes(_mAddress, subAddress, dest, count);
+    else if (settings.device.commInterface == IMU_MODE_SPI)
+        SPIreadBytes(_mAddress, subAddress, dest, count);
+}
+
+void LSM9DS1::initSPI()
+{
+    /* cw
+    pinMode(_xgAddress, OUTPUT);
+    digitalWrite(_xgAddress, HIGH);
+    pinMode(_mAddress, OUTPUT);
+    digitalWrite(_mAddress, HIGH);
+    
+    SPI.begin();
+    // Maximum SPI frequency is 10MHz, could divide by 2 here:
+    SPI.setClockDivider(SPI_CLOCK_DIV2);
+    // Data is read and written MSb first.
+    SPI.setBitOrder(MSBFIRST);
+    // Data is captured on rising edge of clock (CPHA = 0)
+    // Base value of the clock is HIGH (CPOL = 1)
+    SPI.setDataMode(SPI_MODE0);
+    */
+}
+
+void LSM9DS1::SPIwriteByte(uint8_t csPin, uint8_t subAddress, uint8_t data)
+{
+    /*cw
+    digitalWrite(csPin, LOW); // Initiate communication
+    
+    // If write, bit 0 (MSB) should be 0
+    // If single write, bit 1 should be 0
+    SPI.transfer(subAddress & 0x3F); // Send Address
+    SPI.transfer(data); // Send data
+    
+    digitalWrite(csPin, HIGH); // Close communication
+    */
+}
+
+uint8_t LSM9DS1::SPIreadByte(uint8_t csPin, uint8_t subAddress)
+{
+    uint8_t temp;
+    // Use the multiple read function to read 1 byte. 
+    // Value is returned to `temp`.
+    SPIreadBytes(csPin, subAddress, &temp, 1);
+    return temp;
+}
+
+void LSM9DS1::SPIreadBytes(uint8_t csPin, uint8_t subAddress,
+                            uint8_t * dest, uint8_t count)
+{
+    // To indicate a read, set bit 0 (msb) of first byte to 1
+    uint8_t rAddress = 0x80 | (subAddress & 0x3F);
+    // Mag SPI port is different. If we're reading multiple bytes, 
+    // set bit 1 to 1. The remaining six bytes are the address to be read
+    if ((csPin == _mAddress) && count > 1)
+        rAddress |= 0x40;
+    
+    /* cw
+    digitalWrite(csPin, LOW); // Initiate communication
+    SPI.transfer(rAddress);
+    for (int i=0; i<count; i++)
+    {
+        dest[i] = SPI.transfer(0x00); // Read into destination array
+    }
+    digitalWrite(csPin, HIGH); // Close communication
+    */
+}
+
+void LSM9DS1::initI2C()
+{
+    /* cw
+    Wire.begin();   // Initialize I2C library
+    */
+    
+    //already initialized in constructor!
+}
+
+// Wire.h read and write protocols
+void LSM9DS1::I2CwriteByte(uint8_t address, uint8_t subAddress, uint8_t data)
+{
+    /* cw
+    Wire.beginTransmission(address);  // Initialize the Tx buffer
+    Wire.write(subAddress);           // Put slave register address in Tx buffer
+    Wire.write(data);                 // Put data in Tx buffer
+    Wire.endTransmission();           // Send the Tx buffer
+    */
+    char temp_data[2] = {subAddress, data};
+    i2c.write(address, temp_data, 2);
+}
+
+uint8_t LSM9DS1::I2CreadByte(uint8_t address, uint8_t subAddress)
+{
+    /* cw
+    int timeout = LSM9DS1_COMMUNICATION_TIMEOUT;
+    uint8_t data; // `data` will store the register data    
+    
+    Wire.beginTransmission(address);         // Initialize the Tx buffer
+    Wire.write(subAddress);                  // Put slave register address in Tx buffer
+    Wire.endTransmission(true);             // Send the Tx buffer, but send a restart to keep connection alive
+    Wire.requestFrom(address, (uint8_t) 1);  // Read one byte from slave register address 
+    while ((Wire.available() < 1) && (timeout-- > 0))
+        delay(1);
+    
+    if (timeout <= 0)
+        return 255; //! Bad! 255 will be misinterpreted as a good value.
+    
+    data = Wire.read();                      // Fill Rx buffer with result
+    return data;                             // Return data read from slave register
+    */
+    char data;
+    char temp[1] = {subAddress};
+    
+    i2c.write(address, temp, 1);
+    //i2c.write(address & 0xFE);
+    temp[1] = 0x00;
+    i2c.write(address, temp, 1);
+    //i2c.write( address | 0x01);
+    int a = i2c.read(address, &data, 1);
+    return data;
+}
+
+uint8_t LSM9DS1::I2CreadBytes(uint8_t address, uint8_t subAddress, uint8_t * dest, uint8_t count)
+{  
+    /* cw
+    int timeout = LSM9DS1_COMMUNICATION_TIMEOUT;
+    Wire.beginTransmission(address);   // Initialize the Tx buffer
+    // Next send the register to be read. OR with 0x80 to indicate multi-read.
+    Wire.write(subAddress | 0x80);     // Put slave register address in Tx buffer
+
+    Wire.endTransmission(true);             // Send the Tx buffer, but send a restart to keep connection alive
+    uint8_t i = 0;
+    Wire.requestFrom(address, count);  // Read bytes from slave register address 
+    while ((Wire.available() < count) && (timeout-- > 0))
+        delay(1);
+    if (timeout <= 0)
+        return -1;
+    
+    for (int i=0; i<count;)
+    {
+        if (Wire.available())
+        {
+            dest[i++] = Wire.read();
+        }
+    }
+    return count;
+    */
+    int i;
+    char temp_dest[count];
+    char temp[1] = {subAddress};
+    i2c.write(address, temp, 1);
+    i2c.read(address, temp_dest, count);
+    
+    //i2c doesn't take uint8_ts, but rather chars so do this nasty af conversion
+    for (i=0; i < count; i++) {
+        dest[i] = temp_dest[i];    
+    }
+    return count;
+}