/*
 * Author: Jon Trulson <jtrulson@ics.com>
 * Copyright (c) 2015 Intel Corporation.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#pragma once

#include <string>
#include <mraa/common.hpp>
#include <mraa/i2c.hpp>

#include <mraa/gpio.hpp>

#define MPU60X0_I2C_BUS 0
#define MPU60X0_DEFAULT_I2C_ADDR 0x68

namespace upm {
  
  /**
   * @library mpu9150
   * @sensor mpu60x0
   * @comname MPU60X0 3-axis Gyroscope and 3-axis Accelerometer
   * @type accelerometer compass
   * @man seeed
   * @con i2c gpio
   *
   * @brief API for the MPU60X0 3-axis Gyroscope and 3-axis Accelerometer
   *
   * The MPU60X0 devices provide the world’s first integrated 6-axis
   * motion processor solution that eliminates the package-level
   * gyroscope and accelerometer cross-axis misalignment associated
   * with discrete solutions. The devices combine a 3-axis gyroscope
   * and a 3-axis accelerometer on the same silicon die.
   *
   * While not all of the functionality of this device is supported
   * initially, methods and register definitions are provided that
   * should allow an end user to implement whatever features are
   * required.
   *
   * @image html mpu60x0.jpg
   * @snippet mpu60x0.cxx Interesting
   */
  class MPU60X0 {
  public:

    // NOTE: These enums were composed from both the mpu6050 and
    // mpu9150 register maps, since this driver was written using an
    // mpu9150, but we'd like this module to be usable with a
    // standalone mpu60x0.
    //
    // Registers and bitfields marked with an '*' in their
    // comment indicate registers or bit fields present in the mpu9150
    // register map, but not in the original mpu6050 register map.  If
    // using this module on a standalone mpu6050, you should avoid
    // using those registers or bitfields marked with an *.

    /**
     * MPU60X0 registers
     */
    typedef enum {
      REG_SELF_TEST_X           = 0x0d,
      REG_SELF_TEST_Y           = 0x0e,
      REG_SELF_TEST_Z           = 0x0f,
      REG_SELF_TEST_A           = 0x10,

      REG_SMPLRT_DIV            = 0x19, // sample rate divider

      REG_CONFIG                = 0x1a,
      REG_GYRO_CONFIG           = 0x1b,
      REG_ACCEL_CONFIG          = 0x1c,

      REG_FF_THR                = 0x1d, // *freefall threshold
      REG_FF_DUR                = 0x1e, // *freefall duration

      REG_MOT_THR               = 0x1f, // motion threshold
      REG_MOT_DUR               = 0x20, // *motion duration

      REG_ZRMOT_THR             = 0x21, // *zero motion threshhold
      REG_ZRMOT_DUR             = 0x22, // *zero motion duration

      REG_FIFO_EN               = 0x23,

      REG_I2C_MST_CTRL          = 0x24, // I2C master control

      REG_I2C_SLV0_ADDR         = 0x25, // I2C slave 0
      REG_I2C_SLV0_REG          = 0x26,
      REG_I2C_SLV0_CTRL         = 0x27,

      REG_I2C_SLV1_ADDR         = 0x28, // I2C slave 1
      REG_I2C_SLV1_REG          = 0x29,
      REG_I2C_SLV1_CTRL         = 0x2a,

      REG_I2C_SLV2_ADDR         = 0x2b, // I2C slave 2
      REG_I2C_SLV2_REG          = 0x2c,
      REG_I2C_SLV2_CTRL         = 0x2d,

      REG_I2C_SLV3_ADDR         = 0x2e, // I2C slave 3
      REG_I2C_SLV3_REG          = 0x2f,
      REG_I2C_SLV3_CTRL         = 0x30,

      REG_I2C_SLV4_ADDR         = 0x31, // I2C slave 4
      REG_I2C_SLV4_REG          = 0x32,
      REG_I2C_SLV4_DO           = 0x33,
      REG_I2C_SLV4_CTRL         = 0x34,
      REG_I2C_SLV4_DI           = 0x35,

      REG_I2C_MST_STATUS        = 0x36, // I2C master status

      REG_INT_PIN_CFG           = 0x37, // interrupt pin config/i2c bypass
      REG_INT_ENABLE            = 0x38,

      // 0x39 reserved

      REG_INT_STATUS            = 0x3a, // interrupt status

      REG_ACCEL_XOUT_H          = 0x3b, // accelerometer outputs
      REG_ACCEL_XOUT_L          = 0x3c,

      REG_ACCEL_YOUT_H          = 0x3d,
      REG_ACCEL_YOUT_L          = 0x3e,

      REG_ACCEL_ZOUT_H          = 0x3f,
      REG_ACCEL_ZOUT_L          = 0x40,

      REG_TEMP_OUT_H            = 0x41, // temperature output
      REG_TEMP_OUT_L            = 0x42,

      REG_GYRO_XOUT_H           = 0x43, // gyro outputs
      REG_GYRO_XOUT_L           = 0x44,

      REG_GYRO_YOUT_H           = 0x45,
      REG_GYRO_YOUT_L           = 0x46,

      REG_GYRO_ZOUT_H           = 0x47,
      REG_GYRO_ZOUT_L           = 0x48,

      REG_EXT_SENS_DATA_00      = 0x49, // external sensor data
      REG_EXT_SENS_DATA_01      = 0x4a,
      REG_EXT_SENS_DATA_02      = 0x4b,
      REG_EXT_SENS_DATA_03      = 0x4c,
      REG_EXT_SENS_DATA_04      = 0x4d,
      REG_EXT_SENS_DATA_05      = 0x4e,
      REG_EXT_SENS_DATA_06      = 0x4f,
      REG_EXT_SENS_DATA_07      = 0x50,
      REG_EXT_SENS_DATA_08      = 0x51,
      REG_EXT_SENS_DATA_09      = 0x52,
      REG_EXT_SENS_DATA_10      = 0x53,
      REG_EXT_SENS_DATA_11      = 0x54,
      REG_EXT_SENS_DATA_12      = 0x55,
      REG_EXT_SENS_DATA_13      = 0x56,
      REG_EXT_SENS_DATA_14      = 0x57,
      REG_EXT_SENS_DATA_15      = 0x58,
      REG_EXT_SENS_DATA_16      = 0x59,
      REG_EXT_SENS_DATA_17      = 0x5a,
      REG_EXT_SENS_DATA_18      = 0x5b,
      REG_EXT_SENS_DATA_19      = 0x5c,
      REG_EXT_SENS_DATA_20      = 0x5d,
      REG_EXT_SENS_DATA_21      = 0x5e,
      REG_EXT_SENS_DATA_22      = 0x5f,
      REG_EXT_SENS_DATA_23      = 0x60,

      REG_MOT_DETECT_STATUS     = 0x61, // *

      // 0x62 reserved

      REG_I2C_SLV0_DO           = 0x63, // I2C slave data outs
      REG_I2C_SLV1_DO           = 0x64,
      REG_I2C_SLV2_DO           = 0x65,
      REG_I2C_SLV3_DO           = 0x66,

      REG_I2C_MST_DELAY_CTRL    = 0x67,

      REG_SIGNAL_PATH_RESET     = 0x68, // signal path resets

      REG_MOT_DETECT_CTRL       = 0x69,

      REG_USER_CTRL             = 0x6a,

      REG_PWR_MGMT_1            = 0x6b, // power management
      REG_PWR_MGMT_2            = 0x6c,

      // 0x6d-0x71 reserved

      REG_FIFO_COUNTH           = 0x72,
      REG_FIFO_COUNTL           = 0x73,

      REG_FIFO_R_W              = 0x74,

      REG_WHO_AM_I              = 0x75
    } MPU60X0_REG_T;
    
    /**
     * CONFIG bits
     */
    typedef enum {
      CONFIG_DLPF_CFG0            = 0x01, // digital low-pass filter config
      CONFIG_DLPF_CFG1            = 0x02,
      CONFIG_DLPF_CFG2            = 0x04,
      _CONFIG_DLPF_SHIFT          = 0,
      _CONFIG_DLPF_MASK           = 7,

      CONFIG_EXT_SYNC_SET0        = 0x08, // FSYNC pin config
      CONFIG_EXT_SYNC_SET1        = 0x10,
      CONFIG_EXT_SYNC_SET2        = 0x20,
      _CONFIG_EXT_SYNC_SET_SHIFT  = 3,
      _CONFIG_EXT_SYNC_SET_MASK   = 7
    } CONFIG_BITS_T;

    /**
     * CONFIG DLPF_CFG values
     */
    typedef enum {
      DLPF_260_256                = 0, // accel/gyro bandwidth (Hz)
      DLPF_184_188                = 1,
      DLPF_94_98                  = 2,
      DLPF_44_42                  = 3,
      DLPF_21_20                  = 4,
      DLPF_10_10                  = 5,
      DLPF_5_5                    = 6,
      DLPF_RESERVED               = 7
    } DLPF_CFG_T;

    /**
     * CONFIG EXT_SYNC_SET values
     */
    typedef enum {
      EXT_SYNC_DISABLED           = 0,
      EXT_SYNC_TEMP_OUT           = 1,
      EXT_SYNC_GYRO_XOUT          = 2,
      EXT_SYNC_GYRO_YOUT          = 3,
      EXT_SYNC_GYRO_ZOUT          = 4,
      EXT_SYNC_ACCEL_XOUT         = 5,
      EXT_SYNC_ACCEL_YOUT         = 6,
      EXT_SYNC_ACCEL_ZOUT         = 7
    } EXT_SYNC_SET_T;

    /**
     * GYRO_CONFIG bits
     */
    typedef enum {
      // 0x01-0x04 reserved
      FS_SEL0                          = 0x08, // gyro full scale range
      FS_SEL1                          = 0x10,
      _FS_SEL_SHIFT                    = 3,
      _FS_SEL_MASK                     = 3,

      ZG_ST                            = 0x20, // gyro self test bits
      YG_ST                            = 0x40,
      XG_ST                            = 0x80
    } GRYO_CONFIG_BITS_T;

    /**
     * GYRO FS_SEL values
     */
    typedef enum {
      FS_250                           = 0, // 250 deg/s, 131 LSB deg/s
      FS_500                           = 1, // 500 deg/s, 65.5 LSB deg/s
      FS_1000                          = 2, // 1000 deg/s, 32.8 LSB deg/s
      FS_2000                          = 3  // 2000 deg/s, 16.4 LSB deg/s
    } FS_SEL_T;

    /**
     * ACCEL_CONFIG bits
     */
    typedef enum {
      // 0x01-0x04 reserved
      AFS_SEL0                         = 0x08, // accel full scale range
      AFS_SEL1                         = 0x10,
      _AFS_SEL_SHIFT                   = 3,
      _AFS_SEL_MASK                    = 3,

      ZA_ST                            = 0x20, // gyro self test bits
      YA_ST                            = 0x40,
      XA_ST                            = 0x80
    } ACCEL_CONFIG_BITS_T;

    /**
     * ACCEL AFS_SEL (full scaling) values
     */
    typedef enum {
      AFS_2                            = 0, // 2g, 16384 LSB/g
      AFS_4                            = 1, // 4g, 8192 LSB/g
      AFS_8                            = 2, // 8g, 4096 LSB/g
      AFS_16                           = 3  // 16g, 2048 LSB/g
    } AFS_SEL_T;

    /**
     * REG_FIFO_EN bits
     */
    typedef enum {
      SLV0_FIFO_EN                     = 0x01,
      SLV1_FIFO_EN                     = 0x02,
      SLV2_FIFO_EN                     = 0x04,

      ACCEL_FIFO_EN                    = 0x08,

      ZG_FIFO_EN                       = 0x10,
      YG_FIFO_EN                       = 0x20,
      XG_FIFO_EN                       = 0x40,

      TEMP_FIFO_EN                     = 0x80
    } FIFO_EN_BITS_T;

    /**
     * REG_I2C_MST_CTRL bits
     */
    typedef enum {
      I2C_MST_CLK0                     = 0x01,
      I2C_MST_CLK1                     = 0x02,
      I2C_MST_CLK2                     = 0x04,
      I2C_MST_CLK3                     = 0x08,
      _I2C_MST_CLK_SHIFT               = 0,
      _I2C_MST_CLK_MASK                = 15,

      I2C_MST_P_NSR                    = 0x10,

      SLV_3_FIFO_EN                    = 0x20,

      WAIT_FOR_ES                      = 0x40,

      MULT_MST_EN                      = 0x80
    } I2C_MST_CTRL_BITS_T;

    /**
     * I2C_MST_CLK values
     */
    typedef enum {
      MST_CLK_348                      = 0, // 348Khz
      MST_CLK_333                      = 1,
      MST_CLK_320                      = 2,
      MST_CLK_308                      = 3,
      MST_CLK_296                      = 4,
      MST_CLK_286                      = 5,
      MST_CLK_276                      = 6,
      MST_CLK_267                      = 7,
      MST_CLK_258                      = 8,
      MST_CLK_500                      = 9,
      MST_CLK_471                      = 10,
      MST_CLK_444                      = 11,
      MST_CLK_421                      = 12,
      MST_CLK_400                      = 13,
      MST_CLK_381                      = 14,
      MST_CLK_364                      = 15
    } I2C_MST_CLK_T;

    /**
     * REG_I2C SLV0-SLV4 _ADDR bits
     */
    typedef enum {
      I2C_SLV_ADDR0                    = 0x01,
      I2C_SLV_ADDR1                    = 0x02,
      I2C_SLV_ADDR2                    = 0x04,
      I2C_SLV_ADDR3                    = 0x08,
      I2C_SLV_ADDR4                    = 0x10,
      I2C_SLV_ADDR5                    = 0x20,
      I2C_SLV_ADDR6                    = 0x40,
      _I2C_SLV_ADDR_SHIFT              = 0,
      _I2C_SLV_ADDR_MASK               = 127,

      I2C_SLV_RW                       = 0x80
    } I2C_SLV_ADDR_BITS_T;

    /**
     * REG_I2C SLV0-SLV3 _CTRL bits
     */
    typedef enum {
      I2C_SLV_LEN0                     = 0x01,
      I2C_SLV_LEN1                     = 0x02,
      I2C_SLV_LEN2                     = 0x04,
      I2C_SLV_LEN3                     = 0x08,
      _I2C_SLV_LEN_SHIFT               = 0,
      _I2C_SLV_LEN_MASK                = 15,

      I2C_SLV_GRP                      = 0x10,
      I2C_SLV_REG_DIS                  = 0x20,
      I2C_SLV_BYTE_SW                  = 0x40,
      I2C_SLV_EN                       = 0x80
    } I2C_SLV_CTRL_BITS_T;

    /**
     * REG_I2C_SLV4_CTRL bits, these are different from the SLV0-SLV3
     * CRTL bits.
     *
     * MST_DLY is not enumerated in the register map.  It configures
     * the reduced access rate of i2c slaves relative to the sample
     * rate. When a slave’s access rate is decreased relative to the
     * Sample Rate, the slave is accessed every 
     * 1 / (1 + I2C_MST_DLY) samples
     */
    typedef enum {
      I2C_MST_DLY0                     = 0x01,
      I2C_MST_DLY1                     = 0x02,
      I2C_MST_DLY2                     = 0x04,
      I2C_MST_DLY3                     = 0x08,
      I2C_MST_DLY4                     = 0x10,
      _I2C_MST_DLY_SHIFT               = 0,
      _I2C_MST_DLY_MASK                = 31,

      I2C_SLV4_REG_DIS                 = 0x20,
      I2C_SLV4_INT_EN                  = 0x40,
      I2C_SLV4_EN                      = 0x80
    } I2C_SLV4_CTRL_BITS_T;

    /**
     * REG_I2C_MST_STATUS bits
     */
    typedef enum {
      I2C_SLV0_NACK                    = 0x01,
      I2C_SLV1_NACK                    = 0x02,
      I2C_SLV2_NACK                    = 0x04,
      I2C_SLV3_NACK                    = 0x08,
      I2C_SLV4_NACK                    = 0x10,

      I2C_LOST_ARB                     = 0x20,
      I2C_SLV4_DONE                    = 0x40,
      PASS_THROUGH                     = 0x80
    } I2C_MST_STATUS_BITS_T;
    
    /**
     * REG_INT_PIN_CFG bits
     */
    typedef enum {
      CLKOUT_EN                        = 0x01, // *

      I2C_BYPASS_ENABLE                = 0x02,

      FSYNC_INT_EN                     = 0x04,
      FSYNC_INT_LEVEL                  = 0x08,

      INT_RD_CLEAR                     = 0x10,

      LATCH_INT_EN                     = 0x20,

      INT_OPEN                         = 0x40,
      INT_LEVEL                        = 0x80
    } INT_PIN_CFG_BITS_T;
    
    /**
     * REG_INT_ENABLE bits
     */
    typedef enum {
      DATA_RDY_EN                      = 0x01, // *

      // 0x02, 0x04 reserved

      I2C_MST_INT_EN                   = 0x08,

      FIFO_OFLOW_EN                    = 0x10,

      ZMOT_EN                          = 0x20, // *zero motion
      MOT_EN                           = 0x40,
      FF_EN                            = 0x80  // *freefall
    } INT_ENABLE_BITS_T;
    
    /**
     * REG_INT_STATUS bits
     */
    typedef enum {
      DATA_RDY_INT                     = 0x01,

      // 0x02, 0x04 reserved

      I2C_MST_INT                      = 0x08,

      FIFO_OFLOW_INT                   = 0x10,

      ZMOT_INT                         = 0x20, // *zero motion
      MOT_INT                          = 0x40,
      FF_INT                           = 0x80  // *freefall
    } INT_STATUS_BITS_T;
    
    /**
     * REG_MOT_DETECT_STATUS bits (mpu9150 only)
     */
    typedef enum {
      MOT_ZRMOT                        = 0x01, // *

      // 0x02 reserved

      MOT_ZPOS                         = 0x04, // *
      MOT_ZNEG                         = 0x08, // *

      MOT_YPOS                         = 0x10, // *
      MOT_YNEG                         = 0x20, // *

      MOT_XPOS                         = 0x40, // *
      MOT_XNEG                         = 0x80, // *
    } MOT_DETECT_STATUS_BITS_T;
    
    /**
     * REG_MST_DELAY_CTRL bits
     */
    typedef enum {
      I2C_SLV0_DLY_EN                  = 0x01,
      I2C_SLV1_DLY_EN                  = 0x02,
      I2C_SLV2_DLY_EN                  = 0x04,
      I2C_SLV3_DLY_EN                  = 0x08,
      I2C_SLV4_DLY_EN                  = 0x10,

      // 0x20, 0x40, reserved

      DELAY_ES_SHADOW                  = 0x80
    } MST_DELAY_CTRL_BITS_T;
    
    /**
     * REG_SIGNAL_PATH_RESET bits
     */
    typedef enum {
      TEMP_RESET                       = 0x01,
      ACCEL_RESET                      = 0x02,
      GYRO_RESET                       = 0x04

      // 0x08-0x80 reserved
    } SIGNAL_PATH_RESET_BITS_T;
    
    /**
     * REG_MOT_DETECT_CTRL bits
     */
    typedef enum {
      MOT_COUNT0                       = 0x01, // *
      MOT_COUNT1                       = 0x02, // *
      _MOT_COUNT_SHIFT                 = 0,
      _MOT_COUNT_MASK                  = 3,

      FF_COUNT0                        = 0x04, // *
      FF_COUNT1                        = 0x08, // *
      _FF_COUNT_SHIFT                  = 2,
      _FF_COUNT_MASK                   = 3,

      ACCEL_ON_DELAY0                  = 0x10,
      ACCEL_ON_DELAY1                  = 0x20,
      _ACCEL_ON_DELAY_SHIFT            = 4,
      _ACCEL_ON_DELAY_MASK             = 3
      // 0x40,0x80 reserved
    } MOT_DETECT_CTRL_BITS_T;
    
    /**
     * MOT_COUNT or FF_COUNT values (mpu9150 only)
     */
    typedef enum {
      COUNT_0                          = 0, // Reset
      COUNT_1                          = 1, // counter decrement 1
      COUNT_2                          = 2, // counter decrement 2
      COUNT_4                          = 3  // counter decrement 4
    } MOT_FF_COUNT_T;

    /**
     * ACCEL_ON_DELAY values
     */
    typedef enum {
      ON_DELAY_0                       = 0, // no delay
      ON_DELAY_1                       = 1, // add 1ms
      ON_DELAY_2                       = 2, // add 2ms
      ON_DELAY_3                       = 3  // add 3ms
    } ACCEL_ON_DELAY_T;

    /**
     * REG_USER_CTRL bits
     */
    typedef enum {
      SIG_COND_RESET                   = 0x01,
      I2C_MST_RESET                    = 0x02,
      FIFO_RESET                       = 0x04,

      // 0x08 reserved

      I2C_IF_DIS                       = 0x10,
      I2C_MST_EN                       = 0x20,
      FIFO_EN                          = 0x40

      /// 0x80 reserved
    } USER_CTRL_BITS_T;
    
    /**
     * REG_PWR_MGMT_1 bits
     */
    typedef enum {
      CLKSEL0                          = 0x01,
      CLKSEL1                          = 0x02,
      CLKSEL2                          = 0x04,
      _CLKSEL_SHIFT                    = 0,
      _CLKSEL_MASK                     = 7,

      TEMP_DIS                         = 0x08,

      // 0x10 reserved

      PWR_CYCLE                        = 0x20,
      PWR_SLEEP                        = 0x40,
      DEVICE_RESET                     = 0x80
    } PWR_MGMT_1_BITS_T;
    
    /**
     * CLKSEL values
     */
    typedef enum {
      INT_8MHZ                         = 0, // internal 8Mhz osc
      PLL_XG                           = 1, // PLL X axis gyro
      PLL_YG                           = 2, // PLL Y axis gyro
      PLL_ZG                           = 3, // PLL Z axis gyro
      PLL_EXT_32KHZ                    = 4, // PLL with external 32.768Khz ref
      PLL_EXT_19MHZ                    = 5, // PLL with external 19.2Mhz ref
      // 6 - reserved
      CLK_STOP                         = 7  // stops clk
    } CLKSEL_T;

    /**
     * REG_PWR_MGMT_2 bits
     */
    typedef enum {
      STBY_ZG                          = 0x01,
      STBY_YG                          = 0x02,
      STBY_XG                          = 0x04,
      STBY_ZA                          = 0x08,
      STBY_YA                          = 0x10,
      STBY_XA                          = 0x20,

      LP_WAKE_CTRL0                    = 0x40,
      LP_WAKE_CTRL1                    = 0x80,
      _LP_WAKE_CTRL_SHIFT              = 6,
      _LP_WAKE_CTRL_MASK               = 3
    } PWR_MGMT_2_BITS_T;
    
    /**
     * LP_WAKE_CTRL values
     */
    typedef enum {
      LP_WAKE_1_25                     = 0, // wakeup feq: 1.25hz
      LP_WAKE_5                        = 1, // 5hz
      LP_WAKE_20                       = 2, // 20hz
      LP_WAKE_40                       = 3, // 40hz
    } LP_WAKE_CRTL_T;


    /**
     * mpu60x0 constructor
     *
     * @param bus i2c bus to use
     * @param address the address for this device
     */
    MPU60X0(int bus=MPU60X0_I2C_BUS, uint8_t address=MPU60X0_DEFAULT_I2C_ADDR);

    /**
     * MPU60X0 Destructor
     */
    ~MPU60X0();
    
    /**
     * set up initial values and start operation
     *
     * @return true if successful
     */
    bool init();

    /**
     * take a measurement and store the current sensor values
     * internally.  Note, these user facing registers are only updated
     * from the internal device sensor values when the i2c serial
     * traffic is 'idle'.  So, if you are reading the values too fast,
     * the bus may never be idle, and you will just end up reading
     * the same values over and over.
     *
     * Unfortunately, it is is not clear how long 'idle' actually
     * means, so if you see this behavior, reduce the rate at which
     * you are calling update().
     *
     */
    void update();

    /**
     * read a register
     *
     * @param reg the register to read
     * @return the value of the register
     */
    uint8_t readReg(uint8_t reg);

    /**
     * read contiguous refister into a buffer
     *
     * @param reg the register to start reading at
     * @param buffer the buffer to store the results
     * @param len the number of registers to read
     * @return the value of the register
     */
    void readRegs(uint8_t reg, uint8_t *buffer, int len);

    /**
     * write to a register
     *
     * @param reg the register to write to
     * @param val the value to write
     * @return true if successful, false otherwise
     */
    bool writeReg(uint8_t reg, uint8_t val);

    /**
     * enable or disable device sleep
     *
     * @param enable true to put device to sleep, false to wake up
     * @return true if successful, false otherwise
     */
    bool setSleep(bool enable);

    /**
     * specify the clock source for the device to use
     *
     * @param clk one of the CLKSEL_T values
     * @return true if successful, false otherwise
     */
    bool setClockSource(CLKSEL_T clk);

    /**
     * set the scaling mode of the gyroscope
     *
     * @param scale one of the FS_SEL_T values
     * @return true if successful, false otherwise
     */
    bool setGyroscopeScale(FS_SEL_T scale);

    /**
     * set the scaling mode of the accelerometer
     *
     * @param scale one of the AFS_SEL_T values
     * @return true if successful, false otherwise
     */
    bool setAccelerometerScale(AFS_SEL_T scale);

    /**
     * set the Low Pass Digital filter.  This enables filtering (if
     * non-0) of the accelerometer and gyro outputs.
     *
     * @param scale one of the DLPF_CFG_T values
     * @return true if successful, false otherwise
     */
    bool setDigitalLowPassFilter(DLPF_CFG_T dlp);

    /**
     * set the sample rate divider.  This register specifies the
     * divider from the gyro output rate used to generate the Sample
     * Rate.  The sensor registor output, FIFO output, DMP sampling
     * and motion detection are all based on the Sample Rate.
     *
     * The Sample Rate is generated by dividing the gyro output rate
     * by this register:
     *
     * Sample Rate = Gyro output rate / (1 + sample rate divider).
     *
     * The Gyro output rate is 8Khz when the Digital Low Pass Filter
     * (DLPF) is 0 or 7 (DLPF_260_256 or DLPF_RESERVED), and 1Khz
     * otherwise.
     *
     * @param scale one of the DLPF_CFG_T values
     * @return true if successful, false otherwise
     */
    bool setSampleRateDivider(uint8_t div);

    /**
     * get the current Sample Rate divider
     *
     * @return the current sample rate divider
     */
    uint8_t getSampleRateDivider();

    /**
     * get the accelerometer values
     *
     * @param x the returned x value, if arg is non-NULL
     * @param y the returned y value, if arg is non-NULL
     * @param z the returned z value, if arg is non-NULL
     * @return true if successful, false otherwise
     */
    void getAccelerometer(float *x, float *y, float *z);

    /**
     * get the gyroscope values
     *
     * @param x the returned x value, if arg is non-NULL
     * @param y the returned y value, if arg is non-NULL
     * @param z the returned z value, if arg is non-NULL
     * @return true if successful, false otherwise
     */
    void getGyroscope(float *x, float *y, float *z);

#if defined(SWIGJAVA) || defined(JAVACALLBACK)
    /**
     * get the accelerometer values
     *
     * @return Array containing X, Y, Z accelerometer values
     */
    float *getAccelerometer();

    /**
     * get the gyroscope values
     *
     * @return Array containing X, Y, Z gyroscope values
     */
    float *getGyroscope();
#endif


    /**
     * get the temperature value
     *
     * @return the temperature value in degrees Celcius
     */
    virtual float getTemperature();

    /**
     * enable onboard temperature measurement sensor
     *
     * @param enable true to enable temperature sensor, false to disable
     * @return true if successful, false otherwise
     */
    bool enableTemperatureSensor(bool enable);

    /**
     * configure external sync.  An external signal connected to the
     * FSYNC pin can be sampled by configuring EXT_SYNC_SET.  Signal
     * changes to the FSYNC pin are latched so that short strobes may
     * be captured. The latched FSYNC signal will be sampled at the
     * Sampling Rate, as defined in register 25. After sampling, the
     * latch will reset to the current FSYNC signal state.
     *
     * The sampled value will be reported in place of the least
     * significant bit in a sensor data register determined by the
     * value of EXT_SYNC_SET
     *
     * @param val one of the EXT_SYNC_SET_T values
     * @return true if successful, false otherwise
     */
    bool setExternalSync(EXT_SYNC_SET_T val);

    /**
     * enable I2C Bypass.  Enabling this feature allows devices on the
     * MPU60X0 auxiliary I2C bus to be visible on the MCU's I2C bus.
     *
     * @param enable true to I2C bypass
     * @return true if successful, false otherwise
     */
    bool enableI2CBypass(bool enable);

    /**
     * set the motion detection threshold for interrupt generation.
     * Motion is detected when the absolute value of any of the
     * accelerometer measurements exceeds this Motion detection
     * threshold.
     *
     * @param thr threshold
     * @return true if successful, false otherwise
     */
    bool setMotionDetectionThreshold(uint8_t thr);

    /**
     * return the interrupt status register.
     *
     * @return the interrupt status word (see INT_STATUS_BITS_T)
     */
    uint8_t getInterruptStatus();

    /**
     * set the interrupt enables
     *
     * @param enables bitmask of INT_ENABLE_BITS_T values to enable
     * @return true if successful, false otherwise
     */
    bool setInterruptEnables(uint8_t enables);

    /**
     * get the current interrupt enables register
     *
     * @return bitmask of INT_ENABLE_BITS_T values
     */
    uint8_t getInterruptEnables();

    /**
     * set the interrupt pin configuration
     *
     * @param cfg bitmask of INT_PIN_CFG_BITS_T values
     * @return true if successful, false otherwise
     */
    bool setInterruptPinConfig(uint8_t cfg);

    /**
     * get the current interrupt pin configuration
     *
     * @return bitmask of INT_PIN_CFG_BITS_T values
     */
    uint8_t getInterruptPinConfig();
    
    /**
     * install an interrupt handler.
     *
     * @param gpio gpio pin to use as interrupt pin
     * @param level the interrupt trigger level (one of mraa::Edge
     * values).  Make sure that you have configured the interrupt pin
     * (setInterruptPinConfig()) properly for whatever level you
     * choose.
     * @param isr the interrupt handler, accepting a void * argument
     * @param arg the argument to pass the the interrupt handler
     */
#if defined(SWIGJAVA) || defined(JAVACALLBACK)
    void installISR(int gpio, mraa::Edge level, jobject runnable);
#else
    void installISR(int gpio, mraa::Edge level, void (*isr)(void *), void *arg);
#endif

    /**
     * uninstall a previously installed interrupt handler
     *
     */
    void uninstallISR();

  protected:
    // uncompensated accelerometer and gyroscope values
    float m_accelX;
    float m_accelY;
    float m_accelZ;

    float m_gyroX;
    float m_gyroY;
    float m_gyroZ;

    // uncompensated temperature value
    float m_temp;

    // accelerometer and gyro scaling factors, depending on their Full
    // Scale settings.
    float m_accelScale;
    float m_gyroScale;

  private:
    mraa::I2c m_i2c;
    uint8_t m_addr;

    mraa::Gpio *m_gpioIRQ;
  };
}


