LSM6DS3.cpp

/******************************************************************************
    SparkFunLSM6DS3.cpp
    LSM6DS3 Arduino and Teensy Driver

    Marshall Taylor @ SparkFun Electronics
    May 20, 2015
    https://github.com/sparkfun/LSM6DS3_Breakout
    https://github.com/sparkfun/SparkFun_LSM6DS3_Arduino_Library

    Resources:
    Uses Wire.h for i2c operation
    Uses SPI.h for SPI operation
    Either can be omitted if not used

    Development environment specifics:
    Arduino IDE 1.6.4
    Teensy loader 1.23

    This code is released under the [MIT License](http://opensource.org/licenses/MIT).

    Please review the LICENSE.md file included with this example. If you have any questions
    or concerns with licensing, please contact techsupport@sparkfun.com.

    Distributed as-is; no warranty is given.
******************************************************************************/

//See SparkFunLSM6DS3.h for additional topology notes.

#include "LSM6DS3.h"
#include "stdint.h"

#include "Wire.h"
#include "SPI.h"

#if defined(TARGET_SEEED_XIAO_NRF52840_SENSE)
#define Wire Wire1
#endif
#if defined(ARDUINO_XIAO_MG24)
#define Wire Wire1
#define PIN_LSM6DS3TR_C_POWER PD5
#endif

//****************************************************************************//
//
//  LSM6DS3Core functions.
//
//  Construction arguments:
//  ( uint8_t busType, uint8_t inputArg ),
//
//    where inputArg is address for I2C_MODE and chip select pin
//    number for SPI_MODE
//
//  For SPI, construct LSM6DS3Core myIMU(SPI_MODE, 10);
//  For I2C, construct LSM6DS3Core myIMU(I2C_MODE, 0x6B);
//
//  Default construction is I2C mode, address 0x6B.
//
//****************************************************************************//
LSM6DS3Core::LSM6DS3Core(uint8_t busType, uint8_t inputArg) : commInterface(I2C_MODE), I2CAddress(0x6B),
    chipSelectPin(10) {
    commInterface = busType;
    if (commInterface == I2C_MODE) {
        I2CAddress = inputArg;
    }
    if (commInterface == SPI_MODE) {
        chipSelectPin = inputArg;
    }

}

status_t LSM6DS3Core::beginCore(void) {
    status_t returnError = IMU_SUCCESS;
#ifdef PIN_LSM6DS3TR_C_POWER
	pinMode(PIN_LSM6DS3TR_C_POWER, OUTPUT);
    #if defined(TARGET_SEEED_XIAO_NRF52840_SENSE)
    NRF_P1->PIN_CNF[8] = ((uint32_t)NRF_GPIO_PIN_DIR_OUTPUT << GPIO_PIN_CNF_DIR_Pos)
                              | ((uint32_t)NRF_GPIO_PIN_INPUT_DISCONNECT << GPIO_PIN_CNF_INPUT_Pos)
                              | ((uint32_t)NRF_GPIO_PIN_NOPULL << GPIO_PIN_CNF_PULL_Pos)
                              | ((uint32_t)NRF_GPIO_PIN_H0H1 << GPIO_PIN_CNF_DRIVE_Pos)
                              | ((uint32_t)NRF_GPIO_PIN_NOSENSE << GPIO_PIN_CNF_SENSE_Pos);
    #endif
	digitalWrite(PIN_LSM6DS3TR_C_POWER, HIGH);
	delay(10);
#endif
    switch (commInterface) {

        case I2C_MODE:
            Wire.begin();
            break;

        case SPI_MODE:
#ifndef TARGET_SEEED_XIAO_NRF52840_SENSE
            // start the SPI library:
            SPI.begin();
            // Maximum SPI frequency is 10MHz, could divide by 2 here:
            #if defined(ARDUINO_XIAO_RA4M1) || defined(ARDUINO_ARCH_RP2040) || defined(ARDUINO_ARCH_RP2350)
            SPI.beginTransaction(SPISettings(1000000, MSBFIRST, SPI_MODE0));
            #elif defined(ARDUINO_XIAO_MG24)
            SPI.setClockDivider(SPI_CLOCK_DIV4);
            #endif 
            // Data is read and written MSb first.
#ifdef ESP32
            SPI.setBitOrder(SPI_MSBFIRST);
#elif defined(ARDUINO_XIAO_RA4M1)
            // noting
#else
            SPI.setBitOrder(MSBFIRST);
#endif
            // Data is captured on rising edge of clock (CPHA = 0)
            // Base value of the clock is HIGH (CPOL = 1)

            // MODE3 for 328p operation
            #ifdef __AVR__
            SPI.setDataMode(SPI_MODE3);
            #else
            #endif

            // MODE0 for Teensy 3.1 operation
            #ifdef __MK20DX256__
            SPI.setDataMode(SPI_MODE0);
            #else
            #endif

            // initalize the  data ready and chip select pins:
            pinMode(chipSelectPin, OUTPUT);
            digitalWrite(chipSelectPin, HIGH);
#endif
            break;
        default:
            break;
    }

    //Spin for a few ms
    volatile uint8_t temp = 0;
    for (uint16_t i = 0; i < 10000; i++) {
        temp++;
    }

    //Check the ID register to determine if the operation was a success.
    uint8_t readCheck;

    readRegister(&readCheck, LSM6DS3_ACC_GYRO_WHO_AM_I_REG);
    if (!(readCheck == LSM6DS3_ACC_GYRO_WHO_AM_I || readCheck == LSM6DS3_C_ACC_GYRO_WHO_AM_I)) {
        returnError = IMU_HW_ERROR;
    }


    return returnError;

}

//****************************************************************************//
//
//  ReadRegisterRegion
//
//  Parameters:
//    *outputPointer -- Pass &variable (base address of) to save read data to
//    offset -- register to read
//    length -- number of bytes to read
//
//  Note:  Does not know if the target memory space is an array or not, or
//    if there is the array is big enough.  if the variable passed is only
//    two bytes long and 3 bytes are requested, this will over-write some
//    other memory!
//
//****************************************************************************//
status_t LSM6DS3Core::readRegisterRegion(uint8_t* outputPointer, uint8_t offset, uint8_t length) {
    status_t returnError = IMU_SUCCESS;

    //define pointer that will point to the external space
    uint8_t i = 0;
    uint8_t c = 0;
#ifndef TARGET_SEEED_XIAO_NRF52840_SENSE 
    uint8_t tempFFCounter = 0;
#endif
    switch (commInterface) {

        case I2C_MODE:
            Wire.beginTransmission(I2CAddress);
            Wire.write(offset);
            if (Wire.endTransmission() != 0) {
                returnError = IMU_HW_ERROR;
            } else { //OK, all worked, keep going
                // request 6 bytes from slave device
                Wire.requestFrom(I2CAddress, length);
                while ((Wire.available()) && (i < length)) { // slave may send less than requested
                    c = Wire.read(); // receive a byte as character
                    *outputPointer = c;
                    outputPointer++;
                    i++;
                }
            }
            break;

        case SPI_MODE:
#ifndef TARGET_SEEED_XIAO_NRF52840_SENSE
            // take the chip select low to select the device:
            digitalWrite(chipSelectPin, LOW);
            // send the device the register you want to read:
            SPI.transfer(offset | 0x80);  //Ored with "read request" bit
            while (i < length) { // slave may send less than requested
                c = SPI.transfer(0x00); // receive a byte as character
                if (c == 0xFF) {
                    //May have problem
                    tempFFCounter++;
                }
                *outputPointer = c;
                outputPointer++;
                i++;
            }
            if (tempFFCounter == i) {
                //Ok, we've recieved all ones, report
                returnError = IMU_ALL_ONES_WARNING;
            }
            // take the chip select high to de-select:
            digitalWrite(chipSelectPin, HIGH);
#endif
            break;

        default:
            break;
    }

    return returnError;
}

//****************************************************************************//
//
//  ReadRegister
//
//  Parameters:
//    *outputPointer -- Pass &variable (address of) to save read data to
//    offset -- register to read
//
//****************************************************************************//
status_t LSM6DS3Core::readRegister(uint8_t* outputPointer, uint8_t offset) {
    //Return value
    uint8_t result = 0;
    uint8_t numBytes = 1;
    status_t returnError = IMU_SUCCESS;

    switch (commInterface) {

        case I2C_MODE:
            Wire.beginTransmission(I2CAddress);
            Wire.write(offset);
            if (Wire.endTransmission() != 0) {
                returnError = IMU_HW_ERROR;
            }
            Wire.requestFrom(I2CAddress, numBytes);
            while (Wire.available()) { // slave may send less than requested
                result = Wire.read(); // receive a byte as a proper uint8_t
            }
            break;

        case SPI_MODE:
#ifndef TARGET_SEEED_XIAO_NRF52840_SENSE
            // take the chip select low to select the device:
            digitalWrite(chipSelectPin, LOW);
            // send the device the register you want to read:
            SPI.transfer(offset | 0x80);  //Ored with "read request" bit
            // send a value of 0 to read the first byte returned:
            result = SPI.transfer(0x00);
            // take the chip select high to de-select:
            digitalWrite(chipSelectPin, HIGH);

            if (result == 0xFF) {
                //we've recieved all ones, report
                returnError = IMU_ALL_ONES_WARNING;
            }
#endif
            break;

        default:
            break;
    }

    *outputPointer = result;
    return returnError;
}

//****************************************************************************//
//
//  readRegisterInt16
//
//  Parameters:
//    *outputPointer -- Pass &variable (base address of) to save read data to
//    offset -- register to read
//
//****************************************************************************//
status_t LSM6DS3Core::readRegisterInt16(int16_t* outputPointer, uint8_t offset) {
    uint8_t myBuffer[2] = {0, 0};
    status_t returnError = readRegisterRegion(myBuffer, offset, 2);  //Does memory transfer
    int16_t output = (int16_t)myBuffer[0] | int16_t(myBuffer[1] << 8);

    *outputPointer = output;
    return returnError;
}

//****************************************************************************//
//
//  writeRegister
//
//  Parameters:
//    offset -- register to write
//    dataToWrite -- 8 bit data to write to register
//
//****************************************************************************//
status_t LSM6DS3Core::writeRegister(uint8_t offset, uint8_t dataToWrite) {
    status_t returnError = IMU_SUCCESS;
    switch (commInterface) {
        case I2C_MODE:
            //Write the byte
            Wire.beginTransmission(I2CAddress);
            Wire.write(offset);
            Wire.write(dataToWrite);
            if (Wire.endTransmission() != 0) {
                returnError = IMU_HW_ERROR;
            }
            break;

        case SPI_MODE:
#ifndef TARGET_SEEED_XIAO_NRF52840_SENSE
            // take the chip select low to select the device:
            digitalWrite(chipSelectPin, LOW);
            // send the device the register you want to read:
            SPI.transfer(offset);
            // send a value of 0 to read the first byte returned:
            SPI.transfer(dataToWrite);
            // decrement the number of bytes left to read:
            // take the chip select high to de-select:
            digitalWrite(chipSelectPin, HIGH);
#endif
            break;

        //No way to check error on this write (Except to read back but that's not reliable)

        default:
            break;
    }

    return returnError;
}

status_t LSM6DS3Core::embeddedPage(void) {
    status_t returnError = writeRegister(LSM6DS3_ACC_GYRO_RAM_ACCESS, 0x80);

    return returnError;
}

status_t LSM6DS3Core::basePage(void) {
    status_t returnError = writeRegister(LSM6DS3_ACC_GYRO_RAM_ACCESS, 0x00);

    return returnError;
}


//****************************************************************************//
//
//  Main user class -- wrapper for the core class + maths
//
//  Construct with same rules as the core ( uint8_t busType, uint8_t inputArg )
//
//****************************************************************************//
LSM6DS3::LSM6DS3(uint8_t busType, uint8_t inputArg) : LSM6DS3Core(busType, inputArg) {
    //Construct with these default settings

    settings.gyroEnabled = 1;  //Can be 0 or 1
    settings.gyroRange = 2000;   //Max deg/s.  Can be: 125, 245, 500, 1000, 2000
    settings.gyroSampleRate = 416;   //Hz.  Can be: 13, 26, 52, 104, 208, 416, 833, 1666
    settings.gyroBandWidth = 400;  //Hz.  Can be: 50, 100, 200, 400;
    settings.gyroFifoEnabled = 1;  //Set to include gyro in FIFO
    settings.gyroFifoDecimation = 1;  //set 1 for on /1

    settings.accelEnabled = 1;
    settings.accelODROff = 1;
    settings.accelRange = 16;      //Max G force readable.  Can be: 2, 4, 8, 16
    settings.accelSampleRate = 416;  //Hz.  Can be: 13, 26, 52, 104, 208, 416, 833, 1666, 3332, 6664, 13330
    settings.accelBandWidth = 100;  //Hz.  Can be: 50, 100, 200, 400;
    settings.accelFifoEnabled = 1;  //Set to include accelerometer in the FIFO
    settings.accelFifoDecimation = 1;  //set 1 for on /1

    settings.tempEnabled = 1;

    //Select interface mode
    settings.commMode = 1;  //Can be modes 1, 2 or 3

    //FIFO control data
    settings.fifoThreshold = 3000;  //Can be 0 to 4096 (16 bit bytes)
    settings.fifoSampleRate = 10;  //default 10Hz
    settings.fifoModeWord = 0;  //Default off

    allOnesCounter = 0;
    nonSuccessCounter = 0;

}

//****************************************************************************//
//
//  Configuration section
//
//  This uses the stored SensorSettings to start the IMU
//  Use statements such as "myIMU.settings.commInterface = SPI_MODE;" or
//  "myIMU.settings.accelEnabled = 1;" to configure before calling .begin();
//
//****************************************************************************//
status_t LSM6DS3::begin() {
    //Check the settings structure values to determine how to setup the device
    uint8_t dataToWrite = 0;  //Temporary variable

    //Begin the inherited core.  This gets the physical wires connected
    status_t returnError = beginCore();

    //Setup the accelerometer******************************
    dataToWrite = 0; //Start Fresh!
    if (settings.accelEnabled == 1) {
        //Build config reg
        //First patch in filter bandwidth
        switch (settings.accelBandWidth) {
            case 50:
                dataToWrite |= LSM6DS3_ACC_GYRO_BW_XL_50Hz;
                break;
            case 100:
                dataToWrite |= LSM6DS3_ACC_GYRO_BW_XL_100Hz;
                break;
            case 200:
                dataToWrite |= LSM6DS3_ACC_GYRO_BW_XL_200Hz;
                break;
            default:  //set default case to max passthrough
            case 400:
                dataToWrite |= LSM6DS3_ACC_GYRO_BW_XL_400Hz;
                break;
        }
        //Next, patch in full scale
        switch (settings.accelRange) {
            case 2:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_XL_2g;
                break;
            case 4:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_XL_4g;
                break;
            case 8:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_XL_8g;
                break;
            default:  //set default case to 16(max)
            case 16:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_XL_16g;
                break;
        }
        //Lastly, patch in accelerometer ODR
        switch (settings.accelSampleRate) {
            case 13:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_13Hz;
                break;
            case 26:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_26Hz;
                break;
            case 52:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_52Hz;
                break;
            default:  //Set default to 104
            case 104:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_104Hz;
                break;
            case 208:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_208Hz;
                break;
            case 416:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_416Hz;
                break;
            case 833:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_833Hz;
                break;
            case 1660:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_1660Hz;
                break;
            case 3330:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_3330Hz;
                break;
            case 6660:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_6660Hz;
                break;
            case 13330:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_XL_13330Hz;
                break;
        }
    } else {
        //dataToWrite already = 0 (powerdown);
    }

    //Now, write the patched together data
    writeRegister(LSM6DS3_ACC_GYRO_CTRL1_XL, dataToWrite);

    //Set the ODR bit
    readRegister(&dataToWrite, LSM6DS3_ACC_GYRO_CTRL4_C);
    dataToWrite &= ~((uint8_t)LSM6DS3_ACC_GYRO_BW_SCAL_ODR_ENABLED);
    if (settings.accelODROff == 1) {
        dataToWrite |= LSM6DS3_ACC_GYRO_BW_SCAL_ODR_ENABLED;
    }
    writeRegister(LSM6DS3_ACC_GYRO_CTRL4_C, dataToWrite);

    //Setup the gyroscope**********************************************
    dataToWrite = 0; //Start Fresh!
    if (settings.gyroEnabled == 1) {
        //Build config reg
        //First, patch in full scale
        switch (settings.gyroRange) {
            case 125:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_125_ENABLED;
                break;
            case 245:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_G_245dps;
                break;
            case 500:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_G_500dps;
                break;
            case 1000:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_G_1000dps;
                break;
            default:  //Default to full 2000DPS range
            case 2000:
                dataToWrite |= LSM6DS3_ACC_GYRO_FS_G_2000dps;
                break;
        }
        //Lastly, patch in gyro ODR
        switch (settings.gyroSampleRate) {
            case 13:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_13Hz;
                break;
            case 26:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_26Hz;
                break;
            case 52:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_52Hz;
                break;
            default:  //Set default to 104
            case 104:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_104Hz;
                break;
            case 208:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_208Hz;
                break;
            case 416:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_416Hz;
                break;
            case 833:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_833Hz;
                break;
            case 1660:
                dataToWrite |= LSM6DS3_ACC_GYRO_ODR_G_1660Hz;
                break;
        }
    } else {
        //dataToWrite already = 0 (powerdown);
    }
    //Write the byte
    writeRegister(LSM6DS3_ACC_GYRO_CTRL2_G, dataToWrite);

    //Return WHO AM I reg  //Not no mo!
    uint8_t result;
    readRegister(&result, LSM6DS3_ACC_GYRO_WHO_AM_I_REG);

    //Setup the internal temperature sensor
    if (settings.tempEnabled == 1) {
        if (result == LSM6DS3_ACC_GYRO_WHO_AM_I) { //0x69 LSM6DS3
            settings.tempSensitivity = 16;    // Sensitivity to scale 16
        } else if (result == LSM6DS3_C_ACC_GYRO_WHO_AM_I) { //0x6A LSM6dS3-C
            settings.tempSensitivity = 256;    // Sensitivity to scale 256
        }
    }

    return returnError;
}

//****************************************************************************//
//
//  Accelerometer section
//
//****************************************************************************//
int16_t LSM6DS3::readRawAccelX(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTX_L_XL);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatAccelX(void) {
    float output = calcAccel(readRawAccelX());
    return output;
}

int16_t LSM6DS3::readRawAccelY(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTY_L_XL);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatAccelY(void) {
    float output = calcAccel(readRawAccelY());
    return output;
}

int16_t LSM6DS3::readRawAccelZ(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTZ_L_XL);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatAccelZ(void) {
    float output = calcAccel(readRawAccelZ());
    return output;
}

float LSM6DS3::calcAccel(int16_t input) {
    float output = (float)input * 0.061 * (settings.accelRange >> 1) / 1000;
    return output;
}

//****************************************************************************//
//
//  Gyroscope section
//
//****************************************************************************//
int16_t LSM6DS3::readRawGyroX(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTX_L_G);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatGyroX(void) {
    float output = calcGyro(readRawGyroX());
    return output;
}

int16_t LSM6DS3::readRawGyroY(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTY_L_G);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatGyroY(void) {
    float output = calcGyro(readRawGyroY());
    return output;
}

int16_t LSM6DS3::readRawGyroZ(void) {
    int16_t output;
    status_t errorLevel = readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUTZ_L_G);
    if (errorLevel != IMU_SUCCESS) {
        if (errorLevel == IMU_ALL_ONES_WARNING) {
            allOnesCounter++;
        } else {
            nonSuccessCounter++;
        }
    }
    return output;
}
float LSM6DS3::readFloatGyroZ(void) {
    float output = calcGyro(readRawGyroZ());
    return output;
}

float LSM6DS3::calcGyro(int16_t input) {
    uint8_t gyroRangeDivisor = settings.gyroRange / 125;
    if (settings.gyroRange == 245) {
        gyroRangeDivisor = 2;
    }

    float output = (float)input * 4.375 * (gyroRangeDivisor) / 1000;
    return output;
}

//****************************************************************************//
//
//  Temperature section
//
//****************************************************************************//
int16_t LSM6DS3::readRawTemp(void) {
    int16_t output;
    readRegisterInt16(&output, LSM6DS3_ACC_GYRO_OUT_TEMP_L);
    return output;
}

float LSM6DS3::readTempC(void) {
    float output = (float)readRawTemp() / settings.tempSensitivity; //divide by tempSensitivity to scale
    output += 25; //Add 25 degrees to remove offset

    return output;

}

float LSM6DS3::readTempF(void) {
    float output = (float)readRawTemp() / settings.tempSensitivity; //divide by tempSensitivity to scale
    output += 25; //Add 25 degrees to remove offset
    output = (output * 9) / 5 + 32;

    return output;

}

//****************************************************************************//
//
//  FIFO section
//
//****************************************************************************//
void LSM6DS3::fifoBegin(void) {
    //CONFIGURE THE VARIOUS FIFO SETTINGS
    //
    //
    //This section first builds a bunch of config words, then goes through
    //and writes them all.

    //Split and mask the threshold
    uint8_t thresholdLByte = settings.fifoThreshold & 0x00FF;
    uint8_t thresholdHByte = (settings.fifoThreshold & 0x0F00) >> 8;
    //Pedo bits not configured (ctl2)

    //CONFIGURE FIFO_CTRL3
    uint8_t tempFIFO_CTRL3 = 0;
    if (settings.gyroFifoEnabled == 1) {
        //Set up gyro stuff
        //Build on FIFO_CTRL3
        //Set decimation
        tempFIFO_CTRL3 |= (settings.gyroFifoDecimation & 0x07) << 3;

    }
    if (settings.accelFifoEnabled == 1) {
        //Set up accelerometer stuff
        //Build on FIFO_CTRL3
        //Set decimation
        tempFIFO_CTRL3 |= (settings.accelFifoDecimation & 0x07);
    }

    //CONFIGURE FIFO_CTRL4  (nothing for now-- sets data sets 3 and 4
    uint8_t tempFIFO_CTRL4 = 0;


    //CONFIGURE FIFO_CTRL5
    uint8_t tempFIFO_CTRL5 = 0;
    switch (settings.fifoSampleRate) {
        default:  //set default case to 10Hz(slowest)
        case 10:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_10Hz;
            break;
        case 25:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_25Hz;
            break;
        case 50:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_50Hz;
            break;
        case 100:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_100Hz;
            break;
        case 200:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_200Hz;
            break;
        case 400:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_400Hz;
            break;
        case 800:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_800Hz;
            break;
        case 1600:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_1600Hz;
            break;
        case 3300:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_3300Hz;
            break;
        case 6600:
            tempFIFO_CTRL5 |= LSM6DS3_ACC_GYRO_ODR_FIFO_6600Hz;
            break;
    }
    //Hard code the fifo mode here:
    tempFIFO_CTRL5 |= settings.fifoModeWord = 6;  //set mode:

    //Write the data
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_CTRL1, thresholdLByte);
    //Serial.println(thresholdLByte, HEX);
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_CTRL2, thresholdHByte);
    //Serial.println(thresholdHByte, HEX);
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_CTRL3, tempFIFO_CTRL3);
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_CTRL4, tempFIFO_CTRL4);
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_CTRL5, tempFIFO_CTRL5);

}
void LSM6DS3::fifoClear(void) {
    //Drain the fifo data and dump it
    while ((fifoGetStatus() & 0x1000) == 0) {
        fifoRead();
    }

}
int16_t LSM6DS3::fifoRead(void) {
    //Pull the last data from the fifo
    uint8_t tempReadByte = 0;
    uint16_t tempAccumulator = 0;
    readRegister(&tempReadByte, LSM6DS3_ACC_GYRO_FIFO_DATA_OUT_L);
    tempAccumulator = tempReadByte;
    readRegister(&tempReadByte, LSM6DS3_ACC_GYRO_FIFO_DATA_OUT_H);
    tempAccumulator |= ((uint16_t)tempReadByte << 8);

    return tempAccumulator;
}

uint16_t LSM6DS3::fifoGetStatus(void) {
    //Return some data on the state of the fifo
    uint8_t tempReadByte = 0;
    uint16_t tempAccumulator = 0;
    readRegister(&tempReadByte, LSM6DS3_ACC_GYRO_FIFO_STATUS1);
    tempAccumulator = tempReadByte;
    readRegister(&tempReadByte, LSM6DS3_ACC_GYRO_FIFO_STATUS2);
    tempAccumulator |= (tempReadByte << 8);

    return tempAccumulator;

}
void LSM6DS3::fifoEnd(void) {
    // turn off the fifo
    writeRegister(LSM6DS3_ACC_GYRO_FIFO_STATUS1, 0x00);  //Disable
}