library for MPU6050 and MPU9250, supports both I2C and SPI

Dependents:   Seeed_nRF51822_MPU9250

Revision:
0:972f3778c19c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/inv_mpu.c	Thu Dec 10 07:39:48 2015 +0000
@@ -0,0 +1,3341 @@
+/*
+ $License:
+    Copyright (C) 2011-2012 InvenSense Corporation, All Rights Reserved.
+    See included License.txt for License information.
+ $
+ */
+/**
+ *  @addtogroup  DRIVERS Sensor Driver Layer
+ *  @brief       Hardware drivers to communicate with sensors via I2C.
+ *
+ *  @{
+ *      @file       inv_mpu.c
+ *      @brief      An I2C-based driver for Invensense gyroscopes.
+ *      @details    This driver currently works for the following devices:
+ *                  MPU6050
+ *                  MPU6500
+ *                  MPU9150 (or MPU6050 w/ AK8975 on the auxiliary bus)
+ *                  MPU9250 (or MPU6500 w/ AK8963 on the auxiliary bus)
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "inv_mpu.h"
+
+/* The following functions must be defined for this platform:
+ * mpu_hal_write(unsigned char slave_addr, unsigned char reg_addr,
+ *      unsigned char length, unsigned char const *data)
+ * mpu_hal_read(unsigned char slave_addr, unsigned char reg_addr,
+ *      unsigned char length, unsigned char *data)
+ * delay_ms(unsigned long num_ms)
+ * get_ms(unsigned long *count)
+ * reg_int_cb(void (*cb)(void), unsigned char port, unsigned char pin)
+ * labs(long x)
+ * fabsf(float x)
+ * min(int a, int b)
+ */
+#if defined __MBED__			// for mbed platform
+#include "mpu_mbed_config.h"
+#elif defined MOTION_DRIVER_TARGET_MSP430
+#include "msp430.h"
+#include "msp430_i2c.h"
+#include "msp430_clock.h"
+#include "msp430_interrupt.h"
+#define mpu_hal_write   msp430_mpu_hal_write
+#define mpu_hal_read    msp430_mpu_hal_read
+#define delay_ms    msp430_delay_ms
+#define get_ms      msp430_get_clock_ms
+static inline int reg_int_cb(struct int_param_s *int_param)
+{
+    return msp430_reg_int_cb(int_param->cb, int_param->pin, int_param->lp_exit,
+        int_param->active_low);
+}
+#define log_i(...)     do {} while (0)
+#define log_e(...)     do {} while (0)
+/* labs is already defined by TI's toolchain. */
+/* fabs is for doubles. fabsf is for floats. */
+#define fabs        fabsf
+#define min(a,b) ((a<b)?a:b)
+#elif defined EMPL_TARGET_MSP430
+#include "msp430.h"
+#include "msp430_i2c.h"
+#include "msp430_clock.h"
+#include "msp430_interrupt.h"
+#include "log.h"
+#define mpu_hal_write   msp430_mpu_hal_write
+#define mpu_hal_read    msp430_mpu_hal_read
+#define delay_ms    msp430_delay_ms
+#define get_ms      msp430_get_clock_ms
+static inline int reg_int_cb(struct int_param_s *int_param)
+{
+    return msp430_reg_int_cb(int_param->cb, int_param->pin, int_param->lp_exit,
+        int_param->active_low);
+}
+#define log_i       MPL_LOGI
+#define log_e       MPL_LOGE
+/* labs is already defined by TI's toolchain. */
+/* fabs is for doubles. fabsf is for floats. */
+#define fabs        fabsf
+#define min(a,b) ((a<b)?a:b)
+#elif defined EMPL_TARGET_UC3L0
+/* Instead of using the standard TWI driver from the ASF library, we're using
+ * a TWI driver that follows the slave address + register address convention.
+ */
+#include "twi.h"
+#include "delay.h"
+#include "sysclk.h"
+#include "log.h"
+#include "sensors_xplained.h"
+#include "uc3l0_clock.h"
+#define mpu_hal_write(a, b, c, d)   twi_write(a, b, d, c)
+#define mpu_hal_read(a, b, c, d)    twi_read(a, b, d, c)
+/* delay_ms is a function already defined in ASF. */
+#define get_ms  uc3l0_get_clock_ms
+static inline int reg_int_cb(struct int_param_s *int_param)
+{
+    sensor_board_irq_connect(int_param->pin, int_param->cb, int_param->arg);
+    return 0;
+}
+#define log_i       MPL_LOGI
+#define log_e       MPL_LOGE
+/* UC3 is a 32-bit processor, so abs and labs are equivalent. */
+#define labs        abs
+#define fabs(x)     (((x)>0)?(x):-(x))
+
+#else
+#error  Gyro driver is missing the system layer implementations.
+#endif
+
+#if !defined MPU6050 && !defined MPU9150 && !defined MPU6500 && !defined MPU9250
+#error  Which gyro are you using? Define MPUxxxx in your compiler options.
+#endif
+
+/* Time for some messy macro work. =]
+ * #define MPU9150
+ * is equivalent to..
+ * #define MPU6050
+ * #define AK8975_SECONDARY
+ *
+ * #define MPU9250
+ * is equivalent to..
+ * #define MPU6500
+ * #define AK8963_SECONDARY
+ */
+#if defined MPU9150
+#ifndef MPU6050
+#define MPU6050
+#endif                          /* #ifndef MPU6050 */
+#if defined AK8963_SECONDARY
+#error "MPU9150 and AK8963_SECONDARY cannot both be defined."
+#elif !defined AK8975_SECONDARY /* #if defined AK8963_SECONDARY */
+#define AK8975_SECONDARY
+#endif                          /* #if defined AK8963_SECONDARY */
+#elif defined MPU9250           /* #if defined MPU9150 */
+#ifndef MPU6500
+#define MPU6500
+#endif                          /* #ifndef MPU6500 */
+#if defined AK8975_SECONDARY
+#error "MPU9250 and AK8975_SECONDARY cannot both be defined."
+#elif !defined AK8963_SECONDARY /* #if defined AK8975_SECONDARY */
+#define AK8963_SECONDARY
+#endif                          /* #if defined AK8975_SECONDARY */
+#endif                          /* #if defined MPU9150 */
+
+#if defined AK8975_SECONDARY || defined AK8963_SECONDARY
+#define AK89xx_SECONDARY
+#else
+/* #warning "No compass = less profit for Invensense. Lame." */
+#endif
+
+static int set_int_enable(unsigned char enable);
+
+/* Hardware registers needed by driver. */
+struct gyro_reg_s {
+    unsigned char who_am_i;
+    unsigned char rate_div;
+    unsigned char lpf;
+    unsigned char prod_id;
+    unsigned char user_ctrl;
+    unsigned char fifo_en;
+    unsigned char gyro_cfg;
+    unsigned char accel_cfg;
+    unsigned char accel_cfg2;
+    unsigned char lp_accel_odr;
+    unsigned char motion_thr;
+    unsigned char motion_dur;
+    unsigned char fifo_count_h;
+    unsigned char fifo_r_w;
+    unsigned char raw_gyro;
+    unsigned char raw_accel;
+    unsigned char temp;
+    unsigned char int_enable;
+    unsigned char dmp_int_status;
+    unsigned char int_status;
+    unsigned char accel_intel;
+    unsigned char pwr_mgmt_1;
+    unsigned char pwr_mgmt_2;
+    unsigned char int_pin_cfg;
+    unsigned char mem_r_w;
+    unsigned char accel_offs;
+    unsigned char i2c_mst;
+    unsigned char bank_sel;
+    unsigned char mem_start_addr;
+    unsigned char prgm_start_h;
+#if defined AK89xx_SECONDARY
+    unsigned char s0_addr;
+    unsigned char s0_reg;
+    unsigned char s0_ctrl;
+    unsigned char s1_addr;
+    unsigned char s1_reg;
+    unsigned char s1_ctrl;
+    unsigned char s4_ctrl;
+    unsigned char s0_do;
+    unsigned char s1_do;
+    unsigned char i2c_delay_ctrl;
+    unsigned char raw_compass;
+    /* The I2C_MST_VDDIO bit is in this register. */
+    unsigned char yg_offs_tc;
+#endif
+};
+
+/* Information specific to a particular device. */
+struct hw_s {
+    unsigned char addr;
+    unsigned short max_fifo;
+    unsigned char num_reg;
+    unsigned short temp_sens;
+    short temp_offset;
+    unsigned short bank_size;
+#if defined AK89xx_SECONDARY
+    unsigned short compass_fsr;
+#endif
+};
+
+/* When entering motion interrupt mode, the driver keeps track of the
+ * previous state so that it can be restored at a later time.
+ * TODO: This is tacky. Fix it.
+ */
+struct motion_int_cache_s {
+    unsigned short gyro_fsr;
+    unsigned char accel_fsr;
+    unsigned short lpf;
+    unsigned short sample_rate;
+    unsigned char sensors_on;
+    unsigned char fifo_sensors;
+    unsigned char dmp_on;
+};
+
+/* Cached chip configuration data.
+ * TODO: A lot of these can be handled with a bitmask.
+ */
+struct chip_cfg_s {
+    /* Matches gyro_cfg >> 3 & 0x03 */
+    unsigned char gyro_fsr;
+    /* Matches accel_cfg >> 3 & 0x03 */
+    unsigned char accel_fsr;
+    /* Enabled sensors. Uses same masks as fifo_en, NOT pwr_mgmt_2. */
+    unsigned char sensors;
+    /* Matches config register. */
+    unsigned char lpf;
+    unsigned char clk_src;
+    /* Sample rate, NOT rate divider. */
+    unsigned short sample_rate;
+    /* Matches fifo_en register. */
+    unsigned char fifo_enable;
+    /* Matches int enable register. */
+    unsigned char int_enable;
+    /* 1 if devices on auxiliary I2C bus appear on the primary. */
+    unsigned char bypass_mode;
+    /* 1 if half-sensitivity.
+     * NOTE: This doesn't belong here, but everything else in hw_s is const,
+     * and this allows us to save some precious RAM.
+     */
+    unsigned char accel_half;
+    /* 1 if device in low-power accel-only mode. */
+    unsigned char lp_accel_mode;
+    /* 1 if interrupts are only triggered on motion events. */
+    unsigned char int_motion_only;
+    struct motion_int_cache_s cache;
+    /* 1 for active low interrupts. */
+    unsigned char active_low_int;
+    /* 1 for latched interrupts. */
+    unsigned char latched_int;
+    /* 1 if DMP is enabled. */
+    unsigned char dmp_on;
+    /* Ensures that DMP will only be loaded once. */
+    unsigned char dmp_loaded;
+    /* Sampling rate used when DMP is enabled. */
+    unsigned short dmp_sample_rate;
+#ifdef AK89xx_SECONDARY
+    /* Compass sample rate. */
+    unsigned short compass_sample_rate;
+    unsigned char compass_addr;
+    short mag_sens_adj[3];
+#endif
+};
+
+/* Information for self-test. */
+struct test_s {
+    unsigned long gyro_sens;
+    unsigned long accel_sens;
+    unsigned char reg_rate_div;
+    unsigned char reg_lpf;
+    unsigned char reg_gyro_fsr;
+    unsigned char reg_accel_fsr;
+    unsigned short wait_ms;
+    unsigned char packet_thresh;
+    float min_dps;
+    float max_dps;
+    float max_gyro_var;
+    float min_g;
+    float max_g;
+    float max_accel_var;
+#ifdef MPU6500
+    float max_g_offset;
+    unsigned short sample_wait_ms;
+#endif
+};
+
+/* Gyro driver state variables. */
+struct gyro_state_s {
+    const struct gyro_reg_s *reg;
+    const struct hw_s *hw;
+    struct chip_cfg_s chip_cfg;
+    const struct test_s *test;
+};
+
+/* Filter configurations. */
+enum lpf_e {
+    INV_FILTER_256HZ_NOLPF2 = 0,
+    INV_FILTER_188HZ,
+    INV_FILTER_98HZ,
+    INV_FILTER_42HZ,
+    INV_FILTER_20HZ,
+    INV_FILTER_10HZ,
+    INV_FILTER_5HZ,
+    INV_FILTER_2100HZ_NOLPF,
+    NUM_FILTER
+};
+
+/* Full scale ranges. */
+enum gyro_fsr_e {
+    INV_FSR_250DPS = 0,
+    INV_FSR_500DPS,
+    INV_FSR_1000DPS,
+    INV_FSR_2000DPS,
+    NUM_GYRO_FSR
+};
+
+/* Full scale ranges. */
+enum accel_fsr_e {
+    INV_FSR_2G = 0,
+    INV_FSR_4G,
+    INV_FSR_8G,
+    INV_FSR_16G,
+    NUM_ACCEL_FSR
+};
+
+/* Clock sources. */
+enum clock_sel_e {
+    INV_CLK_INTERNAL = 0,
+    INV_CLK_PLL,
+    NUM_CLK
+};
+
+/* Low-power accel wakeup rates. */
+enum lp_accel_rate_e {
+#if defined MPU6050
+    INV_LPA_1_25HZ,
+    INV_LPA_5HZ,
+    INV_LPA_20HZ,
+    INV_LPA_40HZ
+#elif defined MPU6500
+    INV_LPA_0_3125HZ,
+    INV_LPA_0_625HZ,
+    INV_LPA_1_25HZ,
+    INV_LPA_2_5HZ,
+    INV_LPA_5HZ,
+    INV_LPA_10HZ,
+    INV_LPA_20HZ,
+    INV_LPA_40HZ,
+    INV_LPA_80HZ,
+    INV_LPA_160HZ,
+    INV_LPA_320HZ,
+    INV_LPA_640HZ
+#endif
+};
+
+#define BIT_I2C_MST_VDDIO   (0x80)
+#define BIT_FIFO_EN         (0x40)
+#define BIT_DMP_EN          (0x80)
+#define BIT_FIFO_RST        (0x04)
+#define BIT_DMP_RST         (0x08)
+#define BIT_FIFO_OVERFLOW   (0x10)
+#define BIT_DATA_RDY_EN     (0x01)
+#define BIT_DMP_INT_EN      (0x02)
+#define BIT_MOT_INT_EN      (0x40)
+#define BITS_FSR            (0x18)
+#define BITS_LPF            (0x07)
+#define BITS_HPF            (0x07)
+#define BITS_CLK            (0x07)
+#define BIT_FIFO_SIZE_1024  (0x40)
+#define BIT_FIFO_SIZE_2048  (0x80)
+#define BIT_FIFO_SIZE_4096  (0xC0)
+#define BIT_RESET           (0x80)
+#define BIT_SLEEP           (0x40)
+#define BIT_S0_DELAY_EN     (0x01)
+#define BIT_S2_DELAY_EN     (0x04)
+#define BITS_SLAVE_LENGTH   (0x0F)
+#define BIT_SLAVE_BYTE_SW   (0x40)
+#define BIT_SLAVE_GROUP     (0x10)
+#define BIT_SLAVE_EN        (0x80)
+#define BIT_I2C_READ        (0x80)
+#define BITS_I2C_MASTER_DLY (0x1F)
+#define BIT_AUX_IF_EN       (0x20)
+#define BIT_ACTL            (0x80)
+#define BIT_LATCH_EN        (0x20)
+#define BIT_ANY_RD_CLR      (0x10)
+#define BIT_BYPASS_EN       (0x02)
+#define BITS_WOM_EN         (0xC0)
+#define BIT_LPA_CYCLE       (0x20)
+#define BIT_STBY_XA         (0x20)
+#define BIT_STBY_YA         (0x10)
+#define BIT_STBY_ZA         (0x08)
+#define BIT_STBY_XG         (0x04)
+#define BIT_STBY_YG         (0x02)
+#define BIT_STBY_ZG         (0x01)
+#define BIT_STBY_XYZA       (BIT_STBY_XA | BIT_STBY_YA | BIT_STBY_ZA)
+#define BIT_STBY_XYZG       (BIT_STBY_XG | BIT_STBY_YG | BIT_STBY_ZG)
+
+#if defined AK8975_SECONDARY
+#define SUPPORTS_AK89xx_HIGH_SENS   (0x00)
+#define AK89xx_FSR                  (9830)
+#elif defined AK8963_SECONDARY
+#define SUPPORTS_AK89xx_HIGH_SENS   (0x10)
+#define AK89xx_FSR                  (4915)
+#endif
+
+#ifdef AK89xx_SECONDARY
+#define AKM_REG_WHOAMI      (0x00)
+
+#define AKM_REG_ST1         (0x02)
+#define AKM_REG_HXL         (0x03)
+#define AKM_REG_ST2         (0x09)
+
+#define AKM_REG_CNTL        (0x0A)
+#define AKM_REG_ASTC        (0x0C)
+#define AKM_REG_ASAX        (0x10)
+#define AKM_REG_ASAY        (0x11)
+#define AKM_REG_ASAZ        (0x12)
+
+#define AKM_DATA_READY      (0x01)
+#define AKM_DATA_OVERRUN    (0x02)
+#define AKM_OVERFLOW        (0x80)
+#define AKM_DATA_ERROR      (0x40)
+
+#define AKM_BIT_SELF_TEST   (0x40)
+
+#define AKM_POWER_DOWN          (0x00 | SUPPORTS_AK89xx_HIGH_SENS)
+#define AKM_SINGLE_MEASUREMENT  (0x01 | SUPPORTS_AK89xx_HIGH_SENS)
+#define AKM_FUSE_ROM_ACCESS     (0x0F | SUPPORTS_AK89xx_HIGH_SENS)
+#define AKM_MODE_SELF_TEST      (0x08 | SUPPORTS_AK89xx_HIGH_SENS)
+
+#define AKM_WHOAMI      (0x48)
+#endif
+
+#if defined MPU6050
+const struct gyro_reg_s reg = {
+    .who_am_i       = 0x75,
+    .rate_div       = 0x19,
+    .lpf            = 0x1A,
+    .prod_id        = 0x0C,
+    .user_ctrl      = 0x6A,
+    .fifo_en        = 0x23,
+    .gyro_cfg       = 0x1B,
+    .accel_cfg      = 0x1C,
+    .motion_thr     = 0x1F,
+    .motion_dur     = 0x20,
+    .fifo_count_h   = 0x72,
+    .fifo_r_w       = 0x74,
+    .raw_gyro       = 0x43,
+    .raw_accel      = 0x3B,
+    .temp           = 0x41,
+    .int_enable     = 0x38,
+    .dmp_int_status = 0x39,
+    .int_status     = 0x3A,
+    .pwr_mgmt_1     = 0x6B,
+    .pwr_mgmt_2     = 0x6C,
+    .int_pin_cfg    = 0x37,
+    .mem_r_w        = 0x6F,
+    .accel_offs     = 0x06,
+    .i2c_mst        = 0x24,
+    .bank_sel       = 0x6D,
+    .mem_start_addr = 0x6E,
+    .prgm_start_h   = 0x70
+#ifdef AK89xx_SECONDARY
+    ,.raw_compass   = 0x49,
+    .yg_offs_tc     = 0x01,
+    .s0_addr        = 0x25,
+    .s0_reg         = 0x26,
+    .s0_ctrl        = 0x27,
+    .s1_addr        = 0x28,
+    .s1_reg         = 0x29,
+    .s1_ctrl        = 0x2A,
+    .s4_ctrl        = 0x34,
+    .s0_do          = 0x63,
+    .s1_do          = 0x64,
+    .i2c_delay_ctrl = 0x67
+#endif
+};
+const struct hw_s hw = {
+    .addr           = 0x69,
+    .max_fifo       = 1024,
+    .num_reg        = 118,
+    .temp_sens      = 340,
+    .temp_offset    = -521,
+    .bank_size      = 256
+#if defined AK89xx_SECONDARY
+    ,.compass_fsr    = AK89xx_FSR
+#endif
+};
+
+const struct test_s test = {
+    .gyro_sens      = 32768/250,
+    .accel_sens     = 32768/16,
+    .reg_rate_div   = 0,    /* 1kHz. */
+    .reg_lpf        = 1,    /* 188Hz. */
+    .reg_gyro_fsr   = 0,    /* 250dps. */
+    .reg_accel_fsr  = 0x18, /* 16g. */
+    .wait_ms        = 50,
+    .packet_thresh  = 5,    /* 5% */
+    .min_dps        = 10.f,
+    .max_dps        = 105.f,
+    .max_gyro_var   = 0.14f,
+    .min_g          = 0.3f,
+    .max_g          = 0.95f,
+    .max_accel_var  = 0.14f
+};
+
+static struct gyro_state_s st = {
+    .reg = &reg,
+    .hw = &hw,
+    .test = &test
+};
+#elif defined MPU6500
+const struct gyro_reg_s reg = {
+    .who_am_i       = 0x75,
+    .rate_div       = 0x19,
+    .lpf            = 0x1A,
+    .prod_id        = 0x0C,
+    .user_ctrl      = 0x6A,
+    .fifo_en        = 0x23,
+    .gyro_cfg       = 0x1B,
+    .accel_cfg      = 0x1C,
+    .accel_cfg2     = 0x1D,
+    .lp_accel_odr   = 0x1E,
+    .motion_thr     = 0x1F,
+    .motion_dur     = 0x20,
+    .fifo_count_h   = 0x72,
+    .fifo_r_w       = 0x74,
+    .raw_gyro       = 0x43,
+    .raw_accel      = 0x3B,
+    .temp           = 0x41,
+    .int_enable     = 0x38,
+    .dmp_int_status = 0x39,
+    .int_status     = 0x3A,
+    .accel_intel    = 0x69,
+    .pwr_mgmt_1     = 0x6B,
+    .pwr_mgmt_2     = 0x6C,
+    .int_pin_cfg    = 0x37,
+    .mem_r_w        = 0x6F,
+    .accel_offs     = 0x77,
+    .i2c_mst        = 0x24,
+    .bank_sel       = 0x6D,
+    .mem_start_addr = 0x6E,
+    .prgm_start_h   = 0x70
+#ifdef AK89xx_SECONDARY
+    ,.raw_compass   = 0x49,
+    .s0_addr        = 0x25,
+    .s0_reg         = 0x26,
+    .s0_ctrl        = 0x27,
+    .s1_addr        = 0x28,
+    .s1_reg         = 0x29,
+    .s1_ctrl        = 0x2A,
+    .s4_ctrl        = 0x34,
+    .s0_do          = 0x63,
+    .s1_do          = 0x64,
+    .i2c_delay_ctrl = 0x67
+#endif
+};
+const struct hw_s hw = {
+    .addr           = 0x68,
+    .max_fifo       = 1024,
+    .num_reg        = 128,
+    .temp_sens      = 321,
+    .temp_offset    = 0,
+    .bank_size      = 256
+#if defined AK89xx_SECONDARY
+    ,.compass_fsr    = AK89xx_FSR
+#endif
+};
+
+const struct test_s test = {
+    .gyro_sens      = 32768/250,
+    .accel_sens     = 32768/2,  //FSR = +-2G = 16384 LSB/G
+    .reg_rate_div   = 0,    /* 1kHz. */
+    .reg_lpf        = 2,    /* 92Hz low pass filter*/
+    .reg_gyro_fsr   = 0,    /* 250dps. */
+    .reg_accel_fsr  = 0x0,  /* Accel FSR setting = 2g. */
+    .wait_ms        = 200,   //200ms stabilization time
+    .packet_thresh  = 200,    /* 200 samples */
+    .min_dps        = 20.f,  //20 dps for Gyro Criteria C
+    .max_dps        = 60.f, //Must exceed 60 dps threshold for Gyro Criteria B
+    .max_gyro_var   = .5f, //Must exceed +50% variation for Gyro Criteria A
+    .min_g          = .225f, //Accel must exceed Min 225 mg for Criteria B
+    .max_g          = .675f, //Accel cannot exceed Max 675 mg for Criteria B
+    .max_accel_var  = .5f,  //Accel must be within 50% variation for Criteria A
+    .max_g_offset   = .5f,   //500 mg for Accel Criteria C
+    .sample_wait_ms = 10    //10ms sample time wait
+};
+
+static struct gyro_state_s st = {
+    .reg = &reg,
+    .hw = &hw,
+    .test = &test
+};
+#endif
+
+#define MAX_PACKET_LENGTH (12)
+#ifdef MPU6500
+#define HWST_MAX_PACKET_LENGTH (512)
+#endif
+
+#ifdef AK89xx_SECONDARY
+static int setup_compass(void);
+#define MAX_COMPASS_SAMPLE_RATE (100)
+#endif
+
+/**
+ *  @brief      Enable/disable data ready interrupt.
+ *  If the DMP is on, the DMP interrupt is enabled. Otherwise, the data ready
+ *  interrupt is used.
+ *  @param[in]  enable      1 to enable interrupt.
+ *  @return     0 if successful.
+ */
+static int set_int_enable(unsigned char enable)
+{
+    unsigned char tmp;
+
+    if (st.chip_cfg.dmp_on) {
+        if (enable)
+            tmp = BIT_DMP_INT_EN;
+        else
+            tmp = 0x00;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, &tmp))
+            return -1;
+        st.chip_cfg.int_enable = tmp;
+    } else {
+        if (!st.chip_cfg.sensors)
+            return -1;
+        if (enable && st.chip_cfg.int_enable)
+            return 0;
+        if (enable)
+            tmp = BIT_DATA_RDY_EN;
+        else
+            tmp = 0x00;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, &tmp))
+            return -1;
+        st.chip_cfg.int_enable = tmp;
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Register dump for testing.
+ *  @return     0 if successful.
+ */
+int mpu_reg_dump(void)
+{
+    unsigned char ii;
+    unsigned char data;
+
+    for (ii = 0; ii < st.hw->num_reg; ii++) {
+        if (ii == st.reg->fifo_r_w || ii == st.reg->mem_r_w)
+            continue;
+        if (mpu_hal_read(st.hw->addr, ii, 1, &data))
+            return -1;
+        log_i("%#5x: %#5x\r\n", ii, data);
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Read from a single register.
+ *  NOTE: The memory and FIFO read/write registers cannot be accessed.
+ *  @param[in]  reg     Register address.
+ *  @param[out] data    Register data.
+ *  @return     0 if successful.
+ */
+int mpu_read_reg(unsigned char reg, unsigned char *data)
+{
+    if (reg == st.reg->fifo_r_w || reg == st.reg->mem_r_w)
+        return -1;
+    if (reg >= st.hw->num_reg)
+        return -1;
+    return mpu_hal_read(st.hw->addr, reg, 1, data);
+}
+
+/**
+ *  @brief      Initialize hardware.
+ *  Initial configuration:\n
+ *  Gyro FSR: +/- 2000DPS\n
+ *  Accel FSR +/- 2G\n
+ *  DLPF: 42Hz\n
+ *  FIFO rate: 50Hz\n
+ *  Clock source: Gyro PLL\n
+ *  FIFO: Disabled.\n
+ *  Data ready interrupt: Disabled, active low, unlatched.
+ *  @param[in]  int_param   Platform-specific parameters to interrupt API.
+ *  @return     0 if successful.
+ */
+int mpu_init(struct int_param_s *int_param)
+{
+    unsigned char data[6];
+
+    /* Reset device. */
+    data[0] = BIT_RESET;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, data))
+        return -1;
+    delay_ms(100);
+
+    /* Wake up chip. */
+    data[0] = 0x00;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, data))
+        return -1;
+
+   st.chip_cfg.accel_half = 0;
+
+#ifdef MPU6500
+    /* MPU6500 shares 4kB of memory between the DMP and the FIFO. Since the
+     * first 3kB are needed by the DMP, we'll use the last 1kB for the FIFO.
+     */
+    data[0] = BIT_FIFO_SIZE_1024 | 0x8;
+    if (mpu_hal_write(st.hw->addr, st.reg->accel_cfg2, 1, data))
+        return -1;
+#endif
+
+    /* Set to invalid values to ensure no I2C writes are skipped. */
+    st.chip_cfg.sensors = 0xFF;
+    st.chip_cfg.gyro_fsr = 0xFF;
+    st.chip_cfg.accel_fsr = 0xFF;
+    st.chip_cfg.lpf = 0xFF;
+    st.chip_cfg.sample_rate = 0xFFFF;
+    st.chip_cfg.fifo_enable = 0xFF;
+    st.chip_cfg.bypass_mode = 0xFF;
+#ifdef AK89xx_SECONDARY
+    st.chip_cfg.compass_sample_rate = 0xFFFF;
+#endif
+    /* mpu_set_sensors always preserves this setting. */
+    st.chip_cfg.clk_src = INV_CLK_PLL;
+    /* Handled in next call to mpu_set_bypass. */
+    st.chip_cfg.active_low_int = 1;
+    st.chip_cfg.latched_int = 0;
+    st.chip_cfg.int_motion_only = 0;
+    st.chip_cfg.lp_accel_mode = 0;
+    memset(&st.chip_cfg.cache, 0, sizeof(st.chip_cfg.cache));
+    st.chip_cfg.dmp_on = 0;
+    st.chip_cfg.dmp_loaded = 0;
+    st.chip_cfg.dmp_sample_rate = 0;
+
+    if (mpu_set_gyro_fsr(2000))
+        return -1;
+    if (mpu_set_accel_fsr(2))
+        return -1;
+    if (mpu_set_lpf(42))
+        return -1;
+    if (mpu_set_sample_rate(50))
+        return -1;
+    if (mpu_configure_fifo(0))
+        return -1;
+
+    if (int_param)
+        reg_int_cb(int_param);
+
+#ifdef AK89xx_SECONDARY
+    setup_compass();
+    if (mpu_set_compass_sample_rate(10))
+        return -1;
+#else
+    /* Already disabled by setup_compass. */
+    if (mpu_set_bypass(0))
+        return -1;
+#endif
+
+    mpu_set_sensors(0);
+    return 0;
+}
+
+/**
+ *  @brief      Enter low-power accel-only mode.
+ *  In low-power accel mode, the chip goes to sleep and only wakes up to sample
+ *  the accelerometer at one of the following frequencies:
+ *  \n MPU6050: 1.25Hz, 5Hz, 20Hz, 40Hz
+ *  \n MPU6500: 1.25Hz, 2.5Hz, 5Hz, 10Hz, 20Hz, 40Hz, 80Hz, 160Hz, 320Hz, 640Hz
+ *  \n If the requested rate is not one listed above, the device will be set to
+ *  the next highest rate. Requesting a rate above the maximum supported
+ *  frequency will result in an error.
+ *  \n To select a fractional wake-up frequency, round down the value passed to
+ *  @e rate.
+ *  @param[in]  rate        Minimum sampling rate, or zero to disable LP
+ *                          accel mode.
+ *  @return     0 if successful.
+ */
+int mpu_lp_accel_mode(unsigned char rate)
+{
+    unsigned char tmp[2];
+
+    if (rate > 40)
+        return -1;
+
+    if (!rate) {
+        mpu_set_int_latched(0);
+        tmp[0] = 0;
+        tmp[1] = BIT_STBY_XYZG;
+        if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 2, tmp))
+            return -1;
+        st.chip_cfg.lp_accel_mode = 0;
+        return 0;
+    }
+    /* For LP accel, we automatically configure the hardware to produce latched
+     * interrupts. In LP accel mode, the hardware cycles into sleep mode before
+     * it gets a chance to deassert the interrupt pin; therefore, we shift this
+     * responsibility over to the MCU.
+     *
+     * Any register read will clear the interrupt.
+     */
+    mpu_set_int_latched(1);
+#if defined MPU6050
+    tmp[0] = BIT_LPA_CYCLE;
+    if (rate == 1) {
+        tmp[1] = INV_LPA_1_25HZ;
+        mpu_set_lpf(5);
+    } else if (rate <= 5) {
+        tmp[1] = INV_LPA_5HZ;
+        mpu_set_lpf(5);
+    } else if (rate <= 20) {
+        tmp[1] = INV_LPA_20HZ;
+        mpu_set_lpf(10);
+    } else {
+        tmp[1] = INV_LPA_40HZ;
+        mpu_set_lpf(20);
+    }
+    tmp[1] = (tmp[1] << 6) | BIT_STBY_XYZG;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 2, tmp))
+        return -1;
+#elif defined MPU6500
+    /* Set wake frequency. */
+    if (rate == 1)
+        tmp[0] = INV_LPA_1_25HZ;
+    else if (rate == 2)
+        tmp[0] = INV_LPA_2_5HZ;
+    else if (rate <= 5)
+        tmp[0] = INV_LPA_5HZ;
+    else if (rate <= 10)
+        tmp[0] = INV_LPA_10HZ;
+    else if (rate <= 20)
+        tmp[0] = INV_LPA_20HZ;
+    else if (rate <= 40)
+        tmp[0] = INV_LPA_40HZ;
+    else if (rate <= 80)
+        tmp[0] = INV_LPA_80HZ;
+    else if (rate <= 160)
+        tmp[0] = INV_LPA_160HZ;
+    else if (rate <= 320)
+        tmp[0] = INV_LPA_320HZ;
+    else
+        tmp[0] = INV_LPA_640HZ;
+    if (mpu_hal_write(st.hw->addr, st.reg->lp_accel_odr, 1, tmp))
+        return -1;
+    tmp[0] = BIT_LPA_CYCLE;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, tmp))
+        return -1;
+#endif
+    st.chip_cfg.sensors = INV_XYZ_ACCEL;
+    st.chip_cfg.clk_src = 0;
+    st.chip_cfg.lp_accel_mode = 1;
+    mpu_configure_fifo(0);
+
+    return 0;
+}
+
+/**
+ *  @brief      Read raw gyro data directly from the registers.
+ *  @param[out] data        Raw data in hardware units.
+ *  @param[out] timestamp   Timestamp in milliseconds. Null if not needed.
+ *  @return     0 if successful.
+ */
+int mpu_get_gyro_reg(short *data, unsigned long *timestamp)
+{
+    unsigned char tmp[6];
+
+    if (!(st.chip_cfg.sensors & INV_XYZ_GYRO))
+        return -1;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->raw_gyro, 6, tmp))
+        return -1;
+    data[0] = (tmp[0] << 8) | tmp[1];
+    data[1] = (tmp[2] << 8) | tmp[3];
+    data[2] = (tmp[4] << 8) | tmp[5];
+    if (timestamp)
+        get_ms(timestamp);
+    return 0;
+}
+
+/**
+ *  @brief      Read raw accel data directly from the registers.
+ *  @param[out] data        Raw data in hardware units.
+ *  @param[out] timestamp   Timestamp in milliseconds. Null if not needed.
+ *  @return     0 if successful.
+ */
+int mpu_get_accel_reg(short *data, unsigned long *timestamp)
+{
+    unsigned char tmp[6];
+
+    if (!(st.chip_cfg.sensors & INV_XYZ_ACCEL))
+        return -1;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->raw_accel, 6, tmp))
+        return -1;
+    data[0] = (tmp[0] << 8) | tmp[1];
+    data[1] = (tmp[2] << 8) | tmp[3];
+    data[2] = (tmp[4] << 8) | tmp[5];
+    if (timestamp)
+        get_ms(timestamp);
+    return 0;
+}
+
+/**
+ *  @brief      Read temperature data directly from the registers.
+ *  @param[out] data        Data in q16 format.
+ *  @param[out] timestamp   Timestamp in milliseconds. Null if not needed.
+ *  @return     0 if successful.
+ */
+int mpu_get_temperature(long *data, unsigned long *timestamp)
+{
+    unsigned char tmp[2];
+    short raw;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->temp, 2, tmp))
+        return -1;
+    raw = (tmp[0] << 8) | tmp[1];
+    if (timestamp)
+        get_ms(timestamp);
+
+    data[0] = (long)((35 + ((raw - (float)st.hw->temp_offset) / st.hw->temp_sens)) * 65536L);
+    return 0;
+}
+
+/**
+ *  @brief      Read biases to the accel bias 6500 registers.
+ *  This function reads from the MPU6500 accel offset cancellations registers.
+ *  The format are G in +-8G format. The register is initialized with OTP 
+ *  factory trim values.
+ *  @param[in]  accel_bias  returned structure with the accel bias
+ *  @return     0 if successful.
+ */
+int mpu_read_6500_accel_bias(long *accel_bias) {
+	unsigned char data[6];
+	if (mpu_hal_read(st.hw->addr, 0x77, 2, &data[0]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x7A, 2, &data[2]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x7D, 2, &data[4]))
+		return -1;
+	accel_bias[0] = ((long)data[0]<<8) | data[1];
+	accel_bias[1] = ((long)data[2]<<8) | data[3];
+	accel_bias[2] = ((long)data[4]<<8) | data[5];
+	return 0;
+}
+
+/**
+ *  @brief      Read biases to the accel bias 6050 registers.
+ *  This function reads from the MPU6050 accel offset cancellations registers.
+ *  The format are G in +-8G format. The register is initialized with OTP 
+ *  factory trim values.
+ *  @param[in]  accel_bias  returned structure with the accel bias
+ *  @return     0 if successful.
+ */
+int mpu_read_6050_accel_bias(long *accel_bias) {
+	unsigned char data[6];
+	if (mpu_hal_read(st.hw->addr, 0x06, 2, &data[0]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x08, 2, &data[2]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x0A, 2, &data[4]))
+		return -1;
+	accel_bias[0] = ((long)data[0]<<8) | data[1];
+	accel_bias[1] = ((long)data[2]<<8) | data[3];
+	accel_bias[2] = ((long)data[4]<<8) | data[5];
+	return 0;
+}
+
+int mpu_read_6500_gyro_bias(long *gyro_bias) {
+	unsigned char data[6];
+	if (mpu_hal_read(st.hw->addr, 0x13, 2, &data[0]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x15, 2, &data[2]))
+		return -1;
+	if (mpu_hal_read(st.hw->addr, 0x17, 2, &data[4]))
+		return -1;
+	gyro_bias[0] = ((long)data[0]<<8) | data[1];
+	gyro_bias[1] = ((long)data[2]<<8) | data[3];
+	gyro_bias[2] = ((long)data[4]<<8) | data[5];
+	return 0;
+}
+
+/**
+ *  @brief      Push biases to the gyro bias 6500/6050 registers.
+ *  This function expects biases relative to the current sensor output, and
+ *  these biases will be added to the factory-supplied values. Bias inputs are LSB
+ *  in +-1000dps format.
+ *  @param[in]  gyro_bias  New biases.
+ *  @return     0 if successful.
+ */
+int mpu_set_gyro_bias_reg(long *gyro_bias)
+{
+    unsigned char data[6] = {0, 0, 0, 0, 0, 0};
+    int i=0;
+    for(i=0;i<3;i++) {
+    	gyro_bias[i]= (-gyro_bias[i]);
+    }
+    data[0] = (gyro_bias[0] >> 8) & 0xff;
+    data[1] = (gyro_bias[0]) & 0xff;
+    data[2] = (gyro_bias[1] >> 8) & 0xff;
+    data[3] = (gyro_bias[1]) & 0xff;
+    data[4] = (gyro_bias[2] >> 8) & 0xff;
+    data[5] = (gyro_bias[2]) & 0xff;
+    if (mpu_hal_write(st.hw->addr, 0x13, 2, &data[0]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x15, 2, &data[2]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x17, 2, &data[4]))
+        return -1;
+    return 0;
+}
+
+/**
+ *  @brief      Push biases to the accel bias 6050 registers.
+ *  This function expects biases relative to the current sensor output, and
+ *  these biases will be added to the factory-supplied values. Bias inputs are LSB
+ *  in +-8G format.
+ *  @param[in]  accel_bias  New biases.
+ *  @return     0 if successful.
+ */
+int mpu_set_accel_bias_6050_reg(const long *accel_bias)
+{
+    unsigned char data[6] = {0, 0, 0, 0, 0, 0};
+    long accel_reg_bias[3] = {0, 0, 0};
+    long mask = 0x0001;
+    unsigned char mask_bit[3] = {0, 0, 0};
+    unsigned char i = 0;
+    if(mpu_read_6050_accel_bias(accel_reg_bias))
+    	return -1;
+
+    //bit 0 of the 2 byte bias is for temp comp
+    //calculations need to compensate for this and not change it
+    for(i=0; i<3; i++) {
+    	if(accel_reg_bias[i]&mask)
+    		mask_bit[i] = 0x01;
+    }
+
+    accel_reg_bias[0] -= accel_bias[0];
+    accel_reg_bias[1] -= accel_bias[1];
+    accel_reg_bias[2] -= accel_bias[2];
+
+    data[0] = (accel_reg_bias[0] >> 8) & 0xff;
+    data[1] = (accel_reg_bias[0]) & 0xff;
+    data[1] = data[1]|mask_bit[0];
+    data[2] = (accel_reg_bias[1] >> 8) & 0xff;
+    data[3] = (accel_reg_bias[1]) & 0xff;
+    data[3] = data[3]|mask_bit[1];
+    data[4] = (accel_reg_bias[2] >> 8) & 0xff;
+    data[5] = (accel_reg_bias[2]) & 0xff;
+    data[5] = data[5]|mask_bit[2];
+
+    if (mpu_hal_write(st.hw->addr, 0x06, 2, &data[0]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x08, 2, &data[2]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x0A, 2, &data[4]))
+        return -1;
+
+    return 0;
+}
+
+
+/**
+ *  @brief      Push biases to the accel bias 6500 registers.
+ *  This function expects biases relative to the current sensor output, and
+ *  these biases will be added to the factory-supplied values. Bias inputs are LSB
+ *  in +-8G format.
+ *  @param[in]  accel_bias  New biases.
+ *  @return     0 if successful.
+ */
+int mpu_set_accel_bias_6500_reg(const long *accel_bias)
+{
+    unsigned char data[6] = {0, 0, 0, 0, 0, 0};
+    long accel_reg_bias[3] = {0, 0, 0};
+    long mask = 0x0001;
+    unsigned char mask_bit[3] = {0, 0, 0};
+    unsigned char i = 0;
+
+    if(mpu_read_6500_accel_bias(accel_reg_bias))
+    	return -1;
+
+    //bit 0 of the 2 byte bias is for temp comp
+    //calculations need to compensate for this
+    for(i=0; i<3; i++) {
+    	if(accel_reg_bias[i]&mask)
+    		mask_bit[i] = 0x01;
+    }
+
+    accel_reg_bias[0] -= accel_bias[0];
+    accel_reg_bias[1] -= accel_bias[1];
+    accel_reg_bias[2] -= accel_bias[2];
+
+    data[0] = (accel_reg_bias[0] >> 8) & 0xff;
+    data[1] = (accel_reg_bias[0]) & 0xff;
+    data[1] = data[1]|mask_bit[0];
+    data[2] = (accel_reg_bias[1] >> 8) & 0xff;
+    data[3] = (accel_reg_bias[1]) & 0xff;
+    data[3] = data[3]|mask_bit[1];
+    data[4] = (accel_reg_bias[2] >> 8) & 0xff;
+    data[5] = (accel_reg_bias[2]) & 0xff;
+    data[5] = data[5]|mask_bit[2];
+
+    if (mpu_hal_write(st.hw->addr, 0x77, 2, &data[0]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x7A, 2, &data[2]))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, 0x7D, 2, &data[4]))
+        return -1;
+
+    return 0;
+}
+
+/**
+ *  @brief  Reset FIFO read/write pointers.
+ *  @return 0 if successful.
+ */
+int mpu_reset_fifo(void)
+{
+    unsigned char data;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    data = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, &data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, &data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &data))
+        return -1;
+
+    if (st.chip_cfg.dmp_on) {
+        data = BIT_FIFO_RST | BIT_DMP_RST;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &data))
+            return -1;
+        delay_ms(50);
+        data = BIT_DMP_EN | BIT_FIFO_EN;
+        if (st.chip_cfg.sensors & INV_XYZ_COMPASS)
+            data |= BIT_AUX_IF_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &data))
+            return -1;
+        if (st.chip_cfg.int_enable)
+            data = BIT_DMP_INT_EN;
+        else
+            data = 0;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, &data))
+            return -1;
+        data = 0;
+        if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, &data))
+            return -1;
+    } else {
+        data = BIT_FIFO_RST;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &data))
+            return -1;
+        if (st.chip_cfg.bypass_mode || !(st.chip_cfg.sensors & INV_XYZ_COMPASS))
+            data = BIT_FIFO_EN;
+        else
+            data = BIT_FIFO_EN | BIT_AUX_IF_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &data))
+            return -1;
+        delay_ms(50);
+        if (st.chip_cfg.int_enable)
+            data = BIT_DATA_RDY_EN;
+        else
+            data = 0;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, &data))
+            return -1;
+        if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, &st.chip_cfg.fifo_enable))
+            return -1;
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Get the gyro full-scale range.
+ *  @param[out] fsr Current full-scale range.
+ *  @return     0 if successful.
+ */
+int mpu_get_gyro_fsr(unsigned short *fsr)
+{
+    switch (st.chip_cfg.gyro_fsr) {
+    case INV_FSR_250DPS:
+        fsr[0] = 250;
+        break;
+    case INV_FSR_500DPS:
+        fsr[0] = 500;
+        break;
+    case INV_FSR_1000DPS:
+        fsr[0] = 1000;
+        break;
+    case INV_FSR_2000DPS:
+        fsr[0] = 2000;
+        break;
+    default:
+        fsr[0] = 0;
+        break;
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Set the gyro full-scale range.
+ *  @param[in]  fsr Desired full-scale range.
+ *  @return     0 if successful.
+ */
+int mpu_set_gyro_fsr(unsigned short fsr)
+{
+    unsigned char data;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    switch (fsr) {
+    case 250:
+        data = INV_FSR_250DPS << 3;
+        break;
+    case 500:
+        data = INV_FSR_500DPS << 3;
+        break;
+    case 1000:
+        data = INV_FSR_1000DPS << 3;
+        break;
+    case 2000:
+        data = INV_FSR_2000DPS << 3;
+        break;
+    default:
+        return -1;
+    }
+
+    if (st.chip_cfg.gyro_fsr == (data >> 3))
+        return 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->gyro_cfg, 1, &data))
+        return -1;
+    st.chip_cfg.gyro_fsr = data >> 3;
+    return 0;
+}
+
+/**
+ *  @brief      Get the accel full-scale range.
+ *  @param[out] fsr Current full-scale range.
+ *  @return     0 if successful.
+ */
+int mpu_get_accel_fsr(unsigned char *fsr)
+{
+    switch (st.chip_cfg.accel_fsr) {
+    case INV_FSR_2G:
+        fsr[0] = 2;
+        break;
+    case INV_FSR_4G:
+        fsr[0] = 4;
+        break;
+    case INV_FSR_8G:
+        fsr[0] = 8;
+        break;
+    case INV_FSR_16G:
+        fsr[0] = 16;
+        break;
+    default:
+        return -1;
+    }
+    if (st.chip_cfg.accel_half)
+        fsr[0] <<= 1;
+    return 0;
+}
+
+/**
+ *  @brief      Set the accel full-scale range.
+ *  @param[in]  fsr Desired full-scale range.
+ *  @return     0 if successful.
+ */
+int mpu_set_accel_fsr(unsigned char fsr)
+{
+    unsigned char data;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    switch (fsr) {
+    case 2:
+        data = INV_FSR_2G << 3;
+        break;
+    case 4:
+        data = INV_FSR_4G << 3;
+        break;
+    case 8:
+        data = INV_FSR_8G << 3;
+        break;
+    case 16:
+        data = INV_FSR_16G << 3;
+        break;
+    default:
+        return -1;
+    }
+
+    if (st.chip_cfg.accel_fsr == (data >> 3))
+        return 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->accel_cfg, 1, &data))
+        return -1;
+    st.chip_cfg.accel_fsr = data >> 3;
+    return 0;
+}
+
+/**
+ *  @brief      Get the current DLPF setting.
+ *  @param[out] lpf Current LPF setting.
+ *  0 if successful.
+ */
+int mpu_get_lpf(unsigned short *lpf)
+{
+    switch (st.chip_cfg.lpf) {
+    case INV_FILTER_188HZ:
+        lpf[0] = 188;
+        break;
+    case INV_FILTER_98HZ:
+        lpf[0] = 98;
+        break;
+    case INV_FILTER_42HZ:
+        lpf[0] = 42;
+        break;
+    case INV_FILTER_20HZ:
+        lpf[0] = 20;
+        break;
+    case INV_FILTER_10HZ:
+        lpf[0] = 10;
+        break;
+    case INV_FILTER_5HZ:
+        lpf[0] = 5;
+        break;
+    case INV_FILTER_256HZ_NOLPF2:
+    case INV_FILTER_2100HZ_NOLPF:
+    default:
+        lpf[0] = 0;
+        break;
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Set digital low pass filter.
+ *  The following LPF settings are supported: 188, 98, 42, 20, 10, 5.
+ *  @param[in]  lpf Desired LPF setting.
+ *  @return     0 if successful.
+ */
+int mpu_set_lpf(unsigned short lpf)
+{
+    unsigned char data;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    if (lpf >= 188)
+        data = INV_FILTER_188HZ;
+    else if (lpf >= 98)
+        data = INV_FILTER_98HZ;
+    else if (lpf >= 42)
+        data = INV_FILTER_42HZ;
+    else if (lpf >= 20)
+        data = INV_FILTER_20HZ;
+    else if (lpf >= 10)
+        data = INV_FILTER_10HZ;
+    else
+        data = INV_FILTER_5HZ;
+
+    if (st.chip_cfg.lpf == data)
+        return 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->lpf, 1, &data))
+        return -1;
+    st.chip_cfg.lpf = data;
+    return 0;
+}
+
+/**
+ *  @brief      Get sampling rate.
+ *  @param[out] rate    Current sampling rate (Hz).
+ *  @return     0 if successful.
+ */
+int mpu_get_sample_rate(unsigned short *rate)
+{
+    if (st.chip_cfg.dmp_on)
+        return -1;
+    else
+        rate[0] = st.chip_cfg.sample_rate;
+    return 0;
+}
+
+/**
+ *  @brief      Set sampling rate.
+ *  Sampling rate must be between 4Hz and 1kHz.
+ *  @param[in]  rate    Desired sampling rate (Hz).
+ *  @return     0 if successful.
+ */
+int mpu_set_sample_rate(unsigned short rate)
+{
+    unsigned char data;
+
+    if (!(st.chip_cfg.sensors))
+        return -1;
+
+    if (st.chip_cfg.dmp_on)
+        return -1;
+    else {
+        if (st.chip_cfg.lp_accel_mode) {
+            if (rate && (rate <= 40)) {
+                /* Just stay in low-power accel mode. */
+                mpu_lp_accel_mode(rate);
+                return 0;
+            }
+            /* Requested rate exceeds the allowed frequencies in LP accel mode,
+             * switch back to full-power mode.
+             */
+            mpu_lp_accel_mode(0);
+        }
+        if (rate < 4)
+            rate = 4;
+        else if (rate > 1000)
+            rate = 1000;
+
+        data = 1000 / rate - 1;
+        if (mpu_hal_write(st.hw->addr, st.reg->rate_div, 1, &data))
+            return -1;
+
+        st.chip_cfg.sample_rate = 1000 / (1 + data);
+
+#ifdef AK89xx_SECONDARY
+        mpu_set_compass_sample_rate(min(st.chip_cfg.compass_sample_rate, MAX_COMPASS_SAMPLE_RATE));
+#endif
+
+        /* Automatically set LPF to 1/2 sampling rate. */
+        mpu_set_lpf(st.chip_cfg.sample_rate >> 1);
+        return 0;
+    }
+}
+
+/**
+ *  @brief      Get compass sampling rate.
+ *  @param[out] rate    Current compass sampling rate (Hz).
+ *  @return     0 if successful.
+ */
+int mpu_get_compass_sample_rate(unsigned short *rate)
+{
+#ifdef AK89xx_SECONDARY
+    rate[0] = st.chip_cfg.compass_sample_rate;
+    return 0;
+#else
+    rate[0] = 0;
+    return -1;
+#endif
+}
+
+/**
+ *  @brief      Set compass sampling rate.
+ *  The compass on the auxiliary I2C bus is read by the MPU hardware at a
+ *  maximum of 100Hz. The actual rate can be set to a fraction of the gyro
+ *  sampling rate.
+ *
+ *  \n WARNING: The new rate may be different than what was requested. Call
+ *  mpu_get_compass_sample_rate to check the actual setting.
+ *  @param[in]  rate    Desired compass sampling rate (Hz).
+ *  @return     0 if successful.
+ */
+int mpu_set_compass_sample_rate(unsigned short rate)
+{
+#ifdef AK89xx_SECONDARY
+    unsigned char div;
+    if (!rate || rate > st.chip_cfg.sample_rate || rate > MAX_COMPASS_SAMPLE_RATE)
+        return -1;
+
+    div = st.chip_cfg.sample_rate / rate - 1;
+    if (mpu_hal_write(st.hw->addr, st.reg->s4_ctrl, 1, &div))
+        return -1;
+    st.chip_cfg.compass_sample_rate = st.chip_cfg.sample_rate / (div + 1);
+    return 0;
+#else
+    return -1;
+#endif
+}
+
+/**
+ *  @brief      Get gyro sensitivity scale factor.
+ *  @param[out] sens    Conversion from hardware units to dps.
+ *  @return     0 if successful.
+ */
+int mpu_get_gyro_sens(float *sens)
+{
+    switch (st.chip_cfg.gyro_fsr) {
+    case INV_FSR_250DPS:
+        sens[0] = 131.f;
+        break;
+    case INV_FSR_500DPS:
+        sens[0] = 65.5f;
+        break;
+    case INV_FSR_1000DPS:
+        sens[0] = 32.8f;
+        break;
+    case INV_FSR_2000DPS:
+        sens[0] = 16.4f;
+        break;
+    default:
+        return -1;
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Get accel sensitivity scale factor.
+ *  @param[out] sens    Conversion from hardware units to g's.
+ *  @return     0 if successful.
+ */
+int mpu_get_accel_sens(unsigned short *sens)
+{
+    switch (st.chip_cfg.accel_fsr) {
+    case INV_FSR_2G:
+        sens[0] = 16384;
+        break;
+    case INV_FSR_4G:
+        sens[0] = 8092;
+        break;
+    case INV_FSR_8G:
+        sens[0] = 4096;
+        break;
+    case INV_FSR_16G:
+        sens[0] = 2048;
+        break;
+    default:
+        return -1;
+    }
+    if (st.chip_cfg.accel_half)
+        sens[0] >>= 1;
+    return 0;
+}
+
+/**
+ *  @brief      Get current FIFO configuration.
+ *  @e sensors can contain a combination of the following flags:
+ *  \n INV_X_GYRO, INV_Y_GYRO, INV_Z_GYRO
+ *  \n INV_XYZ_GYRO
+ *  \n INV_XYZ_ACCEL
+ *  @param[out] sensors Mask of sensors in FIFO.
+ *  @return     0 if successful.
+ */
+int mpu_get_fifo_config(unsigned char *sensors)
+{
+    sensors[0] = st.chip_cfg.fifo_enable;
+    return 0;
+}
+
+/**
+ *  @brief      Select which sensors are pushed to FIFO.
+ *  @e sensors can contain a combination of the following flags:
+ *  \n INV_X_GYRO, INV_Y_GYRO, INV_Z_GYRO
+ *  \n INV_XYZ_GYRO
+ *  \n INV_XYZ_ACCEL
+ *  @param[in]  sensors Mask of sensors to push to FIFO.
+ *  @return     0 if successful.
+ */
+int mpu_configure_fifo(unsigned char sensors)
+{
+    unsigned char prev;
+    int result = 0;
+
+    /* Compass data isn't going into the FIFO. Stop trying. */
+    sensors &= ~INV_XYZ_COMPASS;
+
+    if (st.chip_cfg.dmp_on)
+        return 0;
+    else {
+        if (!(st.chip_cfg.sensors))
+            return -1;
+        prev = st.chip_cfg.fifo_enable;
+        st.chip_cfg.fifo_enable = sensors & st.chip_cfg.sensors;
+        if (st.chip_cfg.fifo_enable != sensors)
+            /* You're not getting what you asked for. Some sensors are
+             * asleep.
+             */
+            result = -1;
+        else
+            result = 0;
+        if (sensors || st.chip_cfg.lp_accel_mode)
+            set_int_enable(1);
+        else
+            set_int_enable(0);
+        if (sensors) {
+            if (mpu_reset_fifo()) {
+                st.chip_cfg.fifo_enable = prev;
+                return -1;
+            }
+        }
+    }
+
+    return result;
+}
+
+/**
+ *  @brief      Get current power state.
+ *  @param[in]  power_on    1 if turned on, 0 if suspended.
+ *  @return     0 if successful.
+ */
+int mpu_get_power_state(unsigned char *power_on)
+{
+    if (st.chip_cfg.sensors)
+        power_on[0] = 1;
+    else
+        power_on[0] = 0;
+    return 0;
+}
+
+/**
+ *  @brief      Turn specific sensors on/off.
+ *  @e sensors can contain a combination of the following flags:
+ *  \n INV_X_GYRO, INV_Y_GYRO, INV_Z_GYRO
+ *  \n INV_XYZ_GYRO
+ *  \n INV_XYZ_ACCEL
+ *  \n INV_XYZ_COMPASS
+ *  @param[in]  sensors    Mask of sensors to wake.
+ *  @return     0 if successful.
+ */
+int mpu_set_sensors(unsigned char sensors)
+{
+    unsigned char data;
+#ifdef AK89xx_SECONDARY
+    unsigned char user_ctrl;
+#endif
+
+    if (sensors & INV_XYZ_GYRO)
+        data = INV_CLK_PLL;
+    else if (sensors)
+        data = 0;
+    else
+        data = BIT_SLEEP;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, &data)) {
+        st.chip_cfg.sensors = 0;
+        return -1;
+    }
+    st.chip_cfg.clk_src = data & ~BIT_SLEEP;
+
+    data = 0;
+    if (!(sensors & INV_X_GYRO))
+        data |= BIT_STBY_XG;
+    if (!(sensors & INV_Y_GYRO))
+        data |= BIT_STBY_YG;
+    if (!(sensors & INV_Z_GYRO))
+        data |= BIT_STBY_ZG;
+    if (!(sensors & INV_XYZ_ACCEL))
+        data |= BIT_STBY_XYZA;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_2, 1, &data)) {
+        st.chip_cfg.sensors = 0;
+        return -1;
+    }
+
+    if (sensors && (sensors != INV_XYZ_ACCEL))
+        /* Latched interrupts only used in LP accel mode. */
+        mpu_set_int_latched(0);
+
+#ifdef AK89xx_SECONDARY
+#ifdef AK89xx_BYPASS
+    if (sensors & INV_XYZ_COMPASS)
+        mpu_set_bypass(1);
+    else
+        mpu_set_bypass(0);
+#else
+    if (mpu_hal_read(st.hw->addr, st.reg->user_ctrl, 1, &user_ctrl))
+        return -1;
+    /* Handle AKM power management. */
+    if (sensors & INV_XYZ_COMPASS) {
+        data = AKM_SINGLE_MEASUREMENT;
+        user_ctrl |= BIT_AUX_IF_EN;
+    } else {
+        data = AKM_POWER_DOWN;
+        user_ctrl &= ~BIT_AUX_IF_EN;
+    }
+    if (st.chip_cfg.dmp_on)
+        user_ctrl |= BIT_DMP_EN;
+    else
+        user_ctrl &= ~BIT_DMP_EN;
+    if (mpu_hal_write(st.hw->addr, st.reg->s1_do, 1, &data))
+        return -1;
+    /* Enable/disable I2C master mode. */
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &user_ctrl))
+        return -1;
+#endif
+#endif
+
+    st.chip_cfg.sensors = sensors;
+    st.chip_cfg.lp_accel_mode = 0;
+    delay_ms(50);
+    return 0;
+}
+
+/**
+ *  @brief      Read the MPU interrupt status registers.
+ *  @param[out] status  Mask of interrupt bits.
+ *  @return     0 if successful.
+ */
+int mpu_get_int_status(short *status)
+{
+    unsigned char tmp[2];
+    if (!st.chip_cfg.sensors)
+        return -1;
+    if (mpu_hal_read(st.hw->addr, st.reg->dmp_int_status, 2, tmp))
+        return -1;
+    status[0] = (tmp[0] << 8) | tmp[1];
+    return 0;
+}
+
+/**
+ *  @brief      Get one packet from the FIFO.
+ *  If @e sensors does not contain a particular sensor, disregard the data
+ *  returned to that pointer.
+ *  \n @e sensors can contain a combination of the following flags:
+ *  \n INV_X_GYRO, INV_Y_GYRO, INV_Z_GYRO
+ *  \n INV_XYZ_GYRO
+ *  \n INV_XYZ_ACCEL
+ *  \n If the FIFO has no new data, @e sensors will be zero.
+ *  \n If the FIFO is disabled, @e sensors will be zero and this function will
+ *  return a non-zero error code.
+ *  @param[out] gyro        Gyro data in hardware units.
+ *  @param[out] accel       Accel data in hardware units.
+ *  @param[out] timestamp   Timestamp in milliseconds.
+ *  @param[out] sensors     Mask of sensors read from FIFO.
+ *  @param[out] more        Number of remaining packets.
+ *  @return     0 if successful.
+ */
+int mpu_read_fifo(short *gyro, short *accel, unsigned long *timestamp,
+        unsigned char *sensors, unsigned char *more)
+{
+    /* Assumes maximum packet size is gyro (6) + accel (6). */
+    unsigned char data[MAX_PACKET_LENGTH];
+    unsigned char packet_size = 0;
+    unsigned short fifo_count, index = 0;
+
+    if (st.chip_cfg.dmp_on)
+        return -1;
+
+    sensors[0] = 0;
+    if (!st.chip_cfg.sensors)
+        return -1;
+    if (!st.chip_cfg.fifo_enable)
+        return -1;
+
+    if (st.chip_cfg.fifo_enable & INV_X_GYRO)
+        packet_size += 2;
+    if (st.chip_cfg.fifo_enable & INV_Y_GYRO)
+        packet_size += 2;
+    if (st.chip_cfg.fifo_enable & INV_Z_GYRO)
+        packet_size += 2;
+    if (st.chip_cfg.fifo_enable & INV_XYZ_ACCEL)
+        packet_size += 6;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->fifo_count_h, 2, data))
+        return -1;
+    fifo_count = (data[0] << 8) | data[1];
+    if (fifo_count < packet_size)
+        return 0;
+//    log_i("FIFO count: %hd\n", fifo_count);
+    if (fifo_count > (st.hw->max_fifo >> 1)) {
+        /* FIFO is 50% full, better check overflow bit. */
+        if (mpu_hal_read(st.hw->addr, st.reg->int_status, 1, data))
+            return -1;
+        if (data[0] & BIT_FIFO_OVERFLOW) {
+            mpu_reset_fifo();
+            return -2;
+        }
+    }
+    get_ms((unsigned long*)timestamp);
+
+    if (mpu_hal_read(st.hw->addr, st.reg->fifo_r_w, packet_size, data))
+        return -1;
+    more[0] = fifo_count / packet_size - 1;
+    sensors[0] = 0;
+
+    if ((index != packet_size) && st.chip_cfg.fifo_enable & INV_XYZ_ACCEL) {
+        accel[0] = (data[index+0] << 8) | data[index+1];
+        accel[1] = (data[index+2] << 8) | data[index+3];
+        accel[2] = (data[index+4] << 8) | data[index+5];
+        sensors[0] |= INV_XYZ_ACCEL;
+        index += 6;
+    }
+    if ((index != packet_size) && st.chip_cfg.fifo_enable & INV_X_GYRO) {
+        gyro[0] = (data[index+0] << 8) | data[index+1];
+        sensors[0] |= INV_X_GYRO;
+        index += 2;
+    }
+    if ((index != packet_size) && st.chip_cfg.fifo_enable & INV_Y_GYRO) {
+        gyro[1] = (data[index+0] << 8) | data[index+1];
+        sensors[0] |= INV_Y_GYRO;
+        index += 2;
+    }
+    if ((index != packet_size) && st.chip_cfg.fifo_enable & INV_Z_GYRO) {
+        gyro[2] = (data[index+0] << 8) | data[index+1];
+        sensors[0] |= INV_Z_GYRO;
+        index += 2;
+    }
+
+    return 0;
+}
+
+/**
+ *  @brief      Get one unparsed packet from the FIFO.
+ *  This function should be used if the packet is to be parsed elsewhere.
+ *  @param[in]  length  Length of one FIFO packet.
+ *  @param[in]  data    FIFO packet.
+ *  @param[in]  more    Number of remaining packets.
+ */
+int mpu_read_fifo_stream(unsigned short length, unsigned char *data,
+    unsigned char *more)
+{
+    unsigned char tmp[2];
+    unsigned short fifo_count;
+    if (!st.chip_cfg.dmp_on)
+        return -1;
+    if (!st.chip_cfg.sensors)
+        return -1;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->fifo_count_h, 2, tmp))
+        return -1;
+    fifo_count = (tmp[0] << 8) | tmp[1];
+    if (fifo_count < length) {
+        more[0] = 0;
+        return -1;
+    }
+    if (fifo_count > (st.hw->max_fifo >> 1)) {
+        /* FIFO is 50% full, better check overflow bit. */
+        if (mpu_hal_read(st.hw->addr, st.reg->int_status, 1, tmp))
+            return -1;
+        if (tmp[0] & BIT_FIFO_OVERFLOW) {
+            mpu_reset_fifo();
+            return -2;
+        }
+    }
+
+    if (mpu_hal_read(st.hw->addr, st.reg->fifo_r_w, length, data))
+        return -1;
+    more[0] = fifo_count / length - 1;
+    return 0;
+}
+
+/**
+ *  @brief      Set device to bypass mode.
+ *  @param[in]  bypass_on   1 to enable bypass mode.
+ *  @return     0 if successful.
+ */
+int mpu_set_bypass(unsigned char bypass_on)
+{
+    unsigned char tmp;
+
+    if (st.chip_cfg.bypass_mode == bypass_on)
+        return 0;
+
+    if (bypass_on) {
+        if (mpu_hal_read(st.hw->addr, st.reg->user_ctrl, 1, &tmp))
+            return -1;
+        tmp &= ~BIT_AUX_IF_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &tmp))
+            return -1;
+        delay_ms(3);
+        tmp = BIT_BYPASS_EN;
+        if (st.chip_cfg.active_low_int)
+            tmp |= BIT_ACTL;
+        if (st.chip_cfg.latched_int)
+            tmp |= BIT_LATCH_EN | BIT_ANY_RD_CLR;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_pin_cfg, 1, &tmp))
+            return -1;
+    } else {
+        /* Enable I2C master mode if compass is being used. */
+        if (mpu_hal_read(st.hw->addr, st.reg->user_ctrl, 1, &tmp))
+            return -1;
+        if (st.chip_cfg.sensors & INV_XYZ_COMPASS)
+            tmp |= BIT_AUX_IF_EN;
+        else
+            tmp &= ~BIT_AUX_IF_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, &tmp))
+            return -1;
+        delay_ms(3);
+        if (st.chip_cfg.active_low_int)
+            tmp = BIT_ACTL;
+        else
+            tmp = 0;
+        if (st.chip_cfg.latched_int)
+            tmp |= BIT_LATCH_EN | BIT_ANY_RD_CLR;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_pin_cfg, 1, &tmp))
+            return -1;
+    }
+    st.chip_cfg.bypass_mode = bypass_on;
+    return 0;
+}
+
+/**
+ *  @brief      Set interrupt level.
+ *  @param[in]  active_low  1 for active low, 0 for active high.
+ *  @return     0 if successful.
+ */
+int mpu_set_int_level(unsigned char active_low)
+{
+    st.chip_cfg.active_low_int = active_low;
+    return 0;
+}
+
+/**
+ *  @brief      Enable latched interrupts.
+ *  Any MPU register will clear the interrupt.
+ *  @param[in]  enable  1 to enable, 0 to disable.
+ *  @return     0 if successful.
+ */
+int mpu_set_int_latched(unsigned char enable)
+{
+    unsigned char tmp;
+    if (st.chip_cfg.latched_int == enable)
+        return 0;
+
+    if (enable)
+        tmp = BIT_LATCH_EN | BIT_ANY_RD_CLR;
+    else
+        tmp = 0;
+    if (st.chip_cfg.bypass_mode)
+        tmp |= BIT_BYPASS_EN;
+    if (st.chip_cfg.active_low_int)
+        tmp |= BIT_ACTL;
+    if (mpu_hal_write(st.hw->addr, st.reg->int_pin_cfg, 1, &tmp))
+        return -1;
+    st.chip_cfg.latched_int = enable;
+    return 0;
+}
+
+#ifdef MPU6050
+static int get_accel_prod_shift(float *st_shift)
+{
+    unsigned char tmp[4], shift_code[3], ii;
+
+    if (mpu_hal_read(st.hw->addr, 0x0D, 4, tmp))
+        return 0x07;
+
+    shift_code[0] = ((tmp[0] & 0xE0) >> 3) | ((tmp[3] & 0x30) >> 4);
+    shift_code[1] = ((tmp[1] & 0xE0) >> 3) | ((tmp[3] & 0x0C) >> 2);
+    shift_code[2] = ((tmp[2] & 0xE0) >> 3) | (tmp[3] & 0x03);
+    for (ii = 0; ii < 3; ii++) {
+        if (!shift_code[ii]) {
+            st_shift[ii] = 0.f;
+            continue;
+        }
+        /* Equivalent to..
+         * st_shift[ii] = 0.34f * powf(0.92f/0.34f, (shift_code[ii]-1) / 30.f)
+         */
+        st_shift[ii] = 0.34f;
+        while (--shift_code[ii])
+            st_shift[ii] *= 1.034f;
+    }
+    return 0;
+}
+
+static int accel_self_test(long *bias_regular, long *bias_st)
+{
+    int jj, result = 0;
+    float st_shift[3], st_shift_cust, st_shift_var;
+
+    get_accel_prod_shift(st_shift);
+    for(jj = 0; jj < 3; jj++) {
+        st_shift_cust = labs(bias_regular[jj] - bias_st[jj]) / 65536.f;
+        if (st_shift[jj]) {
+            st_shift_var = st_shift_cust / st_shift[jj] - 1.f;
+            if (fabs(st_shift_var) > test.max_accel_var)
+                result |= 1 << jj;
+        } else if ((st_shift_cust < test.min_g) ||
+            (st_shift_cust > test.max_g))
+            result |= 1 << jj;
+    }
+
+    return result;
+}
+
+static int gyro_self_test(long *bias_regular, long *bias_st)
+{
+    int jj, result = 0;
+    unsigned char tmp[3];
+    float st_shift, st_shift_cust, st_shift_var;
+
+    if (mpu_hal_read(st.hw->addr, 0x0D, 3, tmp))
+        return 0x07;
+
+    tmp[0] &= 0x1F;
+    tmp[1] &= 0x1F;
+    tmp[2] &= 0x1F;
+
+    for (jj = 0; jj < 3; jj++) {
+        st_shift_cust = labs(bias_regular[jj] - bias_st[jj]) / 65536.f;
+        if (tmp[jj]) {
+            st_shift = 3275.f / test.gyro_sens;
+            while (--tmp[jj])
+                st_shift *= 1.046f;
+            st_shift_var = st_shift_cust / st_shift - 1.f;
+            if (fabs(st_shift_var) > test.max_gyro_var)
+                result |= 1 << jj;
+        } else if ((st_shift_cust < test.min_dps) ||
+            (st_shift_cust > test.max_dps))
+            result |= 1 << jj;
+    }
+    return result;
+}
+
+#endif 
+#ifdef AK89xx_SECONDARY
+static int compass_self_test(void)
+{
+    int result = 0x07;
+    
+#ifndef MPU_USE_SPI
+    unsigned char tmp[6];
+    unsigned char tries = 10;
+    short data;
+
+    mpu_set_bypass(1);
+
+    tmp[0] = AKM_POWER_DOWN;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, tmp))
+        return 0x07;
+    tmp[0] = AKM_BIT_SELF_TEST;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_ASTC, 1, tmp))
+        goto AKM_restore;
+    tmp[0] = AKM_MODE_SELF_TEST;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, tmp))
+        goto AKM_restore;
+
+    do {
+        delay_ms(10);
+        if (mpu_hal_read(st.chip_cfg.compass_addr, AKM_REG_ST1, 1, tmp))
+            goto AKM_restore;
+        if (tmp[0] & AKM_DATA_READY)
+            break;
+    } while (tries--);
+    if (!(tmp[0] & AKM_DATA_READY))
+        goto AKM_restore;
+
+    if (mpu_hal_read(st.chip_cfg.compass_addr, AKM_REG_HXL, 6, tmp))
+        goto AKM_restore;
+
+    result = 0;
+#if defined MPU9150
+    data = (short)(tmp[1] << 8) | tmp[0];
+    if ((data > 100) || (data < -100))
+        result |= 0x01;
+    data = (short)(tmp[3] << 8) | tmp[2];
+    if ((data > 100) || (data < -100))
+        result |= 0x02;
+    data = (short)(tmp[5] << 8) | tmp[4];
+    if ((data > -300) || (data < -1000))
+        result |= 0x04;
+#elif defined MPU9250
+    data = (short)(tmp[1] << 8) | tmp[0];
+    if ((data > 200) || (data < -200))  
+        result |= 0x01;
+    data = (short)(tmp[3] << 8) | tmp[2];
+    if ((data > 200) || (data < -200))  
+        result |= 0x02;
+    data = (short)(tmp[5] << 8) | tmp[4];
+    if ((data > -800) || (data < -3200))  
+        result |= 0x04;
+#endif
+AKM_restore:
+    tmp[0] = 0 | SUPPORTS_AK89xx_HIGH_SENS;
+    mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_ASTC, 1, tmp);
+    tmp[0] = SUPPORTS_AK89xx_HIGH_SENS;
+    mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, tmp);
+    mpu_set_bypass(0);
+#else
+	// to do - compass self test through spi interface
+#endif
+    
+    return result;
+}
+#endif
+
+static int get_st_biases(long *gyro, long *accel, unsigned char hw_test)
+{
+    unsigned char data[MAX_PACKET_LENGTH];
+    unsigned char packet_count, ii;
+    unsigned short fifo_count;
+
+    data[0] = 0x01;
+    data[1] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 2, data))
+        return -1;
+    delay_ms(200);
+    data[0] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->i2c_mst, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+    data[0] = BIT_FIFO_RST | BIT_DMP_RST;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+    delay_ms(15);
+    data[0] = st.test->reg_lpf;
+    if (mpu_hal_write(st.hw->addr, st.reg->lpf, 1, data))
+        return -1;
+    data[0] = st.test->reg_rate_div;
+    if (mpu_hal_write(st.hw->addr, st.reg->rate_div, 1, data))
+        return -1;
+    if (hw_test)
+        data[0] = st.test->reg_gyro_fsr | 0xE0;
+    else
+        data[0] = st.test->reg_gyro_fsr;
+    if (mpu_hal_write(st.hw->addr, st.reg->gyro_cfg, 1, data))
+        return -1;
+
+    if (hw_test)
+        data[0] = st.test->reg_accel_fsr | 0xE0;
+    else
+        data[0] = test.reg_accel_fsr;
+    if (mpu_hal_write(st.hw->addr, st.reg->accel_cfg, 1, data))
+        return -1;
+    if (hw_test)
+        delay_ms(200);
+
+    /* Fill FIFO for test.wait_ms milliseconds. */
+    data[0] = BIT_FIFO_EN;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+
+    data[0] = INV_XYZ_GYRO | INV_XYZ_ACCEL;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+    delay_ms(test.wait_ms);
+    data[0] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+
+    if (mpu_hal_read(st.hw->addr, st.reg->fifo_count_h, 2, data))
+        return -1;
+
+    fifo_count = (data[0] << 8) | data[1];
+    packet_count = fifo_count / MAX_PACKET_LENGTH;
+    gyro[0] = gyro[1] = gyro[2] = 0;
+    accel[0] = accel[1] = accel[2] = 0;
+
+    for (ii = 0; ii < packet_count; ii++) {
+        short accel_cur[3], gyro_cur[3];
+        if (mpu_hal_read(st.hw->addr, st.reg->fifo_r_w, MAX_PACKET_LENGTH, data))
+            return -1;
+        accel_cur[0] = ((short)data[0] << 8) | data[1];
+        accel_cur[1] = ((short)data[2] << 8) | data[3];
+        accel_cur[2] = ((short)data[4] << 8) | data[5];
+        accel[0] += (long)accel_cur[0];
+        accel[1] += (long)accel_cur[1];
+        accel[2] += (long)accel_cur[2];
+        gyro_cur[0] = (((short)data[6] << 8) | data[7]);
+        gyro_cur[1] = (((short)data[8] << 8) | data[9]);
+        gyro_cur[2] = (((short)data[10] << 8) | data[11]);
+        gyro[0] += (long)gyro_cur[0];
+        gyro[1] += (long)gyro_cur[1];
+        gyro[2] += (long)gyro_cur[2];
+    }
+#ifdef EMPL_NO_64BIT
+    gyro[0] = (long)(((float)gyro[0]*65536.f) / test.gyro_sens / packet_count);
+    gyro[1] = (long)(((float)gyro[1]*65536.f) / test.gyro_sens / packet_count);
+    gyro[2] = (long)(((float)gyro[2]*65536.f) / test.gyro_sens / packet_count);
+    if (has_accel) {
+        accel[0] = (long)(((float)accel[0]*65536.f) / test.accel_sens /
+            packet_count);
+        accel[1] = (long)(((float)accel[1]*65536.f) / test.accel_sens /
+            packet_count);
+        accel[2] = (long)(((float)accel[2]*65536.f) / test.accel_sens /
+            packet_count);
+        /* Don't remove gravity! */
+        accel[2] -= 65536L;
+    }
+#else
+    gyro[0] = (long)(((long long)gyro[0]<<16) / test.gyro_sens / packet_count);
+    gyro[1] = (long)(((long long)gyro[1]<<16) / test.gyro_sens / packet_count);
+    gyro[2] = (long)(((long long)gyro[2]<<16) / test.gyro_sens / packet_count);
+    accel[0] = (long)(((long long)accel[0]<<16) / test.accel_sens /
+        packet_count);
+    accel[1] = (long)(((long long)accel[1]<<16) / test.accel_sens /
+        packet_count);
+    accel[2] = (long)(((long long)accel[2]<<16) / test.accel_sens /
+        packet_count);
+    /* Don't remove gravity! */
+    if (accel[2] > 0L)
+        accel[2] -= 65536L;
+    else
+        accel[2] += 65536L;
+#endif
+
+    return 0;
+}
+
+#ifdef MPU6500
+#define REG_6500_XG_ST_DATA     0x0
+#define REG_6500_XA_ST_DATA     0xD
+static const unsigned short mpu_6500_st_tb[256] = {
+	2620,2646,2672,2699,2726,2753,2781,2808, //7
+	2837,2865,2894,2923,2952,2981,3011,3041, //15
+	3072,3102,3133,3165,3196,3228,3261,3293, //23
+	3326,3359,3393,3427,3461,3496,3531,3566, //31
+	3602,3638,3674,3711,3748,3786,3823,3862, //39
+	3900,3939,3979,4019,4059,4099,4140,4182, //47
+	4224,4266,4308,4352,4395,4439,4483,4528, //55
+	4574,4619,4665,4712,4759,4807,4855,4903, //63
+	4953,5002,5052,5103,5154,5205,5257,5310, //71
+	5363,5417,5471,5525,5581,5636,5693,5750, //79
+	5807,5865,5924,5983,6043,6104,6165,6226, //87
+	6289,6351,6415,6479,6544,6609,6675,6742, //95
+	6810,6878,6946,7016,7086,7157,7229,7301, //103
+	7374,7448,7522,7597,7673,7750,7828,7906, //111
+	7985,8065,8145,8227,8309,8392,8476,8561, //119
+	8647,8733,8820,8909,8998,9088,9178,9270,
+	9363,9457,9551,9647,9743,9841,9939,10038,
+	10139,10240,10343,10446,10550,10656,10763,10870,
+	10979,11089,11200,11312,11425,11539,11654,11771,
+	11889,12008,12128,12249,12371,12495,12620,12746,
+	12874,13002,13132,13264,13396,13530,13666,13802,
+	13940,14080,14221,14363,14506,14652,14798,14946,
+	15096,15247,15399,15553,15709,15866,16024,16184,
+	16346,16510,16675,16842,17010,17180,17352,17526,
+	17701,17878,18057,18237,18420,18604,18790,18978,
+	19167,19359,19553,19748,19946,20145,20347,20550,
+	20756,20963,21173,21385,21598,21814,22033,22253,
+	22475,22700,22927,23156,23388,23622,23858,24097,
+	24338,24581,24827,25075,25326,25579,25835,26093,
+	26354,26618,26884,27153,27424,27699,27976,28255,
+	28538,28823,29112,29403,29697,29994,30294,30597,
+	30903,31212,31524,31839,32157,32479,32804,33132
+};
+static int accel_6500_self_test(long *bias_regular, long *bias_st, int debug)
+{
+    int i, result = 0, otp_value_zero = 0;
+    float accel_st_al_min, accel_st_al_max;
+    float st_shift_cust[3], st_shift_ratio[3], ct_shift_prod[3], accel_offset_max;
+    unsigned char regs[3];
+    if (mpu_hal_read(st.hw->addr, REG_6500_XA_ST_DATA, 3, regs)) {
+    	if(debug)
+    		log_i("Reading OTP Register Error.\n");
+    	return 0x07;
+    }
+    if(debug)
+    	log_i("Accel OTP:%d, %d, %d\n", regs[0], regs[1], regs[2]);
+	for (i = 0; i < 3; i++) {
+		if (regs[i] != 0) {
+			ct_shift_prod[i] = mpu_6500_st_tb[regs[i] - 1];
+			ct_shift_prod[i] *= 65536.f;
+			ct_shift_prod[i] /= test.accel_sens;
+		}
+		else {
+			ct_shift_prod[i] = 0;
+			otp_value_zero = 1;
+		}
+	}
+	if(otp_value_zero == 0) {
+		if(debug)
+			log_i("ACCEL:CRITERIA A\n");
+		for (i = 0; i < 3; i++) {
+			st_shift_cust[i] = bias_st[i] - bias_regular[i];
+			if(debug) {
+				log_i("Bias_Shift=%7.4f, Bias_Reg=%7.4f, Bias_HWST=%7.4f\r\n",
+						st_shift_cust[i]/1.f, bias_regular[i]/1.f,
+						bias_st[i]/1.f);
+				log_i("OTP value: %7.4f\r\n", ct_shift_prod[i]/1.f);
+			}
+
+			st_shift_ratio[i] = st_shift_cust[i] / ct_shift_prod[i] - 1.f;
+
+			if(debug)
+				log_i("ratio=%7.4f, threshold=%7.4f\r\n", st_shift_ratio[i]/1.f,
+							test.max_accel_var/1.f);
+
+			if (fabs(st_shift_ratio[i]) > test.max_accel_var) {
+				if(debug)
+					log_i("ACCEL Fail Axis = %d\n", i);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+	else {
+		/* Self Test Pass/Fail Criteria B */
+		accel_st_al_min = test.min_g * 65536.f;
+		accel_st_al_max = test.max_g * 65536.f;
+
+		if(debug) {
+			log_i("ACCEL:CRITERIA B\r\n");
+			log_i("Min MG: %7.4f\r\n", accel_st_al_min/1.f);
+			log_i("Max MG: %7.4f\r\n", accel_st_al_max/1.f);
+		}
+
+		for (i = 0; i < 3; i++) {
+			st_shift_cust[i] = bias_st[i] - bias_regular[i];
+
+			if(debug)
+				log_i("Bias_shift=%7.4f, st=%7.4f, reg=%7.4f\n", st_shift_cust[i]/1.f, bias_st[i]/1.f, bias_regular[i]/1.f);
+			if(st_shift_cust[i] < accel_st_al_min || st_shift_cust[i] > accel_st_al_max) {
+				if(debug)
+					log_i("Accel FAIL axis:%d <= 225mg or >= 675mg\n", i);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+
+	if(result == 0) {
+	/* Self Test Pass/Fail Criteria C */
+		accel_offset_max = test.max_g_offset * 65536.f;
+		if(debug)
+			log_i("Accel:CRITERIA C: bias less than %7.4f\n", accel_offset_max/1.f);
+		for (i = 0; i < 3; i++) {
+			if(fabs(bias_regular[i]) > accel_offset_max) {
+				if(debug)
+					log_i("FAILED: Accel axis:%d = %d > 500mg\n", i, bias_regular[i]);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+
+    return result;
+}
+
+static int gyro_6500_self_test(long *bias_regular, long *bias_st, int debug)
+{
+    int i, result = 0, otp_value_zero = 0;
+    float gyro_st_al_max;
+    float st_shift_cust[3], st_shift_ratio[3], ct_shift_prod[3], gyro_offset_max;
+    unsigned char regs[3];
+
+    if (mpu_hal_read(st.hw->addr, REG_6500_XG_ST_DATA, 3, regs)) {
+    	if(debug)
+    		log_i("Reading OTP Register Error.\n");
+        return 0x07;
+    }
+
+    if(debug)
+    	log_i("Gyro OTP:%d, %d, %d\r\n", regs[0], regs[1], regs[2]);
+
+	for (i = 0; i < 3; i++) {
+		if (regs[i] != 0) {
+			ct_shift_prod[i] = mpu_6500_st_tb[regs[i] - 1];
+			ct_shift_prod[i] *= 65536.f;
+			ct_shift_prod[i] /= test.gyro_sens;
+		}
+		else {
+			ct_shift_prod[i] = 0;
+			otp_value_zero = 1;
+		}
+	}
+
+	if(otp_value_zero == 0) {
+		if(debug)
+			log_i("GYRO:CRITERIA A\n");
+		/* Self Test Pass/Fail Criteria A */
+		for (i = 0; i < 3; i++) {
+			st_shift_cust[i] = bias_st[i] - bias_regular[i];
+
+			if(debug) {
+				log_i("Bias_Shift=%7.4f, Bias_Reg=%7.4f, Bias_HWST=%7.4f\r\n",
+						st_shift_cust[i]/1.f, bias_regular[i]/1.f,
+						bias_st[i]/1.f);
+				log_i("OTP value: %7.4f\r\n", ct_shift_prod[i]/1.f);
+			}
+
+			st_shift_ratio[i] = st_shift_cust[i] / ct_shift_prod[i];
+
+			if(debug)
+				log_i("ratio=%7.4f, threshold=%7.4f\r\n", st_shift_ratio[i]/1.f,
+							test.max_gyro_var/1.f);
+
+			if (fabs(st_shift_ratio[i]) < test.max_gyro_var) {
+				if(debug)
+					log_i("Gyro Fail Axis = %d\n", i);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+	else {
+		/* Self Test Pass/Fail Criteria B */
+		gyro_st_al_max = test.max_dps * 65536.f;
+
+		if(debug) {
+			log_i("GYRO:CRITERIA B\r\n");
+			log_i("Max DPS: %7.4f\r\n", gyro_st_al_max/1.f);
+		}
+
+		for (i = 0; i < 3; i++) {
+			st_shift_cust[i] = bias_st[i] - bias_regular[i];
+
+			if(debug)
+				log_i("Bias_shift=%7.4f, st=%7.4f, reg=%7.4f\n", st_shift_cust[i]/1.f, bias_st[i]/1.f, bias_regular[i]/1.f);
+			if(st_shift_cust[i] < gyro_st_al_max) {
+				if(debug)
+					log_i("GYRO FAIL axis:%d greater than 60dps\n", i);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+
+	if(result == 0) {
+	/* Self Test Pass/Fail Criteria C */
+		gyro_offset_max = test.min_dps * 65536.f;
+		if(debug)
+			log_i("Gyro:CRITERIA C: bias less than %7.4f\n", gyro_offset_max/1.f);
+		for (i = 0; i < 3; i++) {
+			if(fabs(bias_regular[i]) > gyro_offset_max) {
+				if(debug)
+					log_i("FAILED: Gyro axis:%d = %d > 20dps\n", i, bias_regular[i]);
+				result |= 1 << i;	//Error condition
+			}
+		}
+	}
+    return result;
+}
+
+static int get_st_6500_biases(long *gyro, long *accel, unsigned char hw_test, int debug)
+{
+    unsigned char data[HWST_MAX_PACKET_LENGTH];
+    unsigned char packet_count, ii;
+    unsigned short fifo_count;
+    int s = 0, read_size = 0, ind;
+
+    data[0] = 0x01;
+    data[1] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 2, data))
+        return -1;
+    delay_ms(200);
+    data[0] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->i2c_mst, 1, data))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+    data[0] = BIT_FIFO_RST | BIT_DMP_RST;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+    delay_ms(15);
+    data[0] = st.test->reg_lpf;
+    if (mpu_hal_write(st.hw->addr, st.reg->lpf, 1, data))
+        return -1;
+    data[0] = st.test->reg_rate_div;
+    if (mpu_hal_write(st.hw->addr, st.reg->rate_div, 1, data))
+        return -1;
+    if (hw_test)
+        data[0] = st.test->reg_gyro_fsr | 0xE0;
+    else
+        data[0] = st.test->reg_gyro_fsr;
+    if (mpu_hal_write(st.hw->addr, st.reg->gyro_cfg, 1, data))
+        return -1;
+
+    if (hw_test)
+        data[0] = st.test->reg_accel_fsr | 0xE0;
+    else
+        data[0] = test.reg_accel_fsr;
+    if (mpu_hal_write(st.hw->addr, st.reg->accel_cfg, 1, data))
+        return -1;
+
+    delay_ms(test.wait_ms);  //wait 200ms for sensors to stabilize
+
+    /* Enable FIFO */
+    data[0] = BIT_FIFO_EN;
+    if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 1, data))
+        return -1;
+    data[0] = INV_XYZ_GYRO | INV_XYZ_ACCEL;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+
+    //initialize the bias return values
+    gyro[0] = gyro[1] = gyro[2] = 0;
+    accel[0] = accel[1] = accel[2] = 0;
+
+    if(debug)
+    	log_i("Starting Bias Loop Reads\n");
+
+    //start reading samples
+    while (s < test.packet_thresh) {
+    	delay_ms(test.sample_wait_ms); //wait 10ms to fill FIFO
+		if (mpu_hal_read(st.hw->addr, st.reg->fifo_count_h, 2, data))
+			return -1;
+		fifo_count = (data[0] << 8) | data[1];
+		packet_count = fifo_count / MAX_PACKET_LENGTH;
+		if ((test.packet_thresh - s) < packet_count)
+		            packet_count = test.packet_thresh - s;
+		read_size = packet_count * MAX_PACKET_LENGTH;
+
+		//burst read from FIFO
+		if (mpu_hal_read(st.hw->addr, st.reg->fifo_r_w, read_size, data))
+						return -1;
+		ind = 0;
+		for (ii = 0; ii < packet_count; ii++) {
+			short accel_cur[3], gyro_cur[3];
+			accel_cur[0] = ((short)data[ind + 0] << 8) | data[ind + 1];
+			accel_cur[1] = ((short)data[ind + 2] << 8) | data[ind + 3];
+			accel_cur[2] = ((short)data[ind + 4] << 8) | data[ind + 5];
+			accel[0] += (long)accel_cur[0];
+			accel[1] += (long)accel_cur[1];
+			accel[2] += (long)accel_cur[2];
+			gyro_cur[0] = (((short)data[ind + 6] << 8) | data[ind + 7]);
+			gyro_cur[1] = (((short)data[ind + 8] << 8) | data[ind + 9]);
+			gyro_cur[2] = (((short)data[ind + 10] << 8) | data[ind + 11]);
+			gyro[0] += (long)gyro_cur[0];
+			gyro[1] += (long)gyro_cur[1];
+			gyro[2] += (long)gyro_cur[2];
+			ind += MAX_PACKET_LENGTH;
+		}
+		s += packet_count;
+    }
+
+    if(debug)
+    	log_i("Samples: %d\n", s);
+
+    //stop FIFO
+    data[0] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->fifo_en, 1, data))
+        return -1;
+
+    gyro[0] = (long)(((long long)gyro[0]<<16) / test.gyro_sens / s);
+    gyro[1] = (long)(((long long)gyro[1]<<16) / test.gyro_sens / s);
+    gyro[2] = (long)(((long long)gyro[2]<<16) / test.gyro_sens / s);
+    accel[0] = (long)(((long long)accel[0]<<16) / test.accel_sens / s);
+    accel[1] = (long)(((long long)accel[1]<<16) / test.accel_sens / s);
+    accel[2] = (long)(((long long)accel[2]<<16) / test.accel_sens / s);
+    /* remove gravity from bias calculation */
+    if (accel[2] > 0L)
+        accel[2] -= 65536L;
+    else
+        accel[2] += 65536L;
+
+
+    if(debug) {
+    	log_i("Accel offset data HWST bit=%d: %7.4f %7.4f %7.4f\r\n", hw_test, accel[0]/65536.f, accel[1]/65536.f, accel[2]/65536.f);
+    	log_i("Gyro offset data HWST bit=%d: %7.4f %7.4f %7.4f\r\n", hw_test, gyro[0]/65536.f, gyro[1]/65536.f, gyro[2]/65536.f);
+    }
+
+    return 0;
+}
+/**
+ *  @brief      Trigger gyro/accel/compass self-test for MPU6500/MPU9250
+ *  On success/error, the self-test returns a mask representing the sensor(s)
+ *  that failed. For each bit, a one (1) represents a "pass" case; conversely,
+ *  a zero (0) indicates a failure.
+ *
+ *  \n The mask is defined as follows:
+ *  \n Bit 0:   Gyro.
+ *  \n Bit 1:   Accel.
+ *  \n Bit 2:   Compass.
+ *
+ *  @param[out] gyro        Gyro biases in q16 format.
+ *  @param[out] accel       Accel biases (if applicable) in q16 format.
+ *  @param[in]  debug       Debug flag used to print out more detailed logs. Must first set up logging in Motion Driver.
+ *  @return     Result mask (see above).
+ */
+int mpu_run_6500_self_test(long *gyro, long *accel, unsigned char debug)
+{
+    const unsigned char tries = 2;
+    long gyro_st[3], accel_st[3];
+    unsigned char accel_result, gyro_result;
+#ifdef AK89xx_SECONDARY
+    unsigned char compass_result;
+#endif
+    int ii;
+
+    int result;
+    unsigned char accel_fsr, fifo_sensors, sensors_on;
+    unsigned short gyro_fsr, sample_rate, lpf;
+    unsigned char dmp_was_on;
+
+
+
+    if(debug)
+    	log_i("Starting MPU6500 HWST!\r\n");
+
+    if (st.chip_cfg.dmp_on) {
+        mpu_set_dmp_state(0);
+        dmp_was_on = 1;
+    } else
+        dmp_was_on = 0;
+
+    /* Get initial settings. */
+    mpu_get_gyro_fsr(&gyro_fsr);
+    mpu_get_accel_fsr(&accel_fsr);
+    mpu_get_lpf(&lpf);
+    mpu_get_sample_rate(&sample_rate);
+    sensors_on = st.chip_cfg.sensors;
+    mpu_get_fifo_config(&fifo_sensors);
+
+    if(debug)
+    	log_i("Retrieving Biases\r\n");
+
+    for (ii = 0; ii < tries; ii++)
+        if (!get_st_6500_biases(gyro, accel, 0, debug))
+            break;
+    if (ii == tries) {
+        /* If we reach this point, we most likely encountered an I2C error.
+         * We'll just report an error for all three sensors.
+         */
+        if(debug)
+        	log_i("Retrieving Biases Error - possible I2C error\n");
+
+        result = 0;
+        goto restore;
+    }
+
+    if(debug)
+    	log_i("Retrieving ST Biases\n");
+
+    for (ii = 0; ii < tries; ii++)
+        if (!get_st_6500_biases(gyro_st, accel_st, 1, debug))
+            break;
+    if (ii == tries) {
+
+        if(debug)
+        	log_i("Retrieving ST Biases Error - possible I2C error\n");
+
+        /* Again, probably an I2C error. */
+        result = 0;
+        goto restore;
+    }
+
+    accel_result = accel_6500_self_test(accel, accel_st, debug);
+    if(debug)
+    	log_i("Accel Self Test Results: %d\n", accel_result);
+
+    gyro_result = gyro_6500_self_test(gyro, gyro_st, debug);
+    if(debug)
+    	log_i("Gyro Self Test Results: %d\n", gyro_result);
+
+    result = 0;
+    if (!gyro_result)
+        result |= 0x01;
+    if (!accel_result)
+        result |= 0x02;
+
+#ifdef AK89xx_SECONDARY
+    compass_result = compass_self_test();
+    if(debug)
+    	log_i("Compass Self Test Results: %d\n", compass_result);
+    if (!compass_result)
+        result |= 0x04;
+#else
+    result |= 0x04;
+#endif
+restore:
+	if(debug)
+		log_i("Exiting HWST\n");
+	/* Set to invalid values to ensure no I2C writes are skipped. */
+	st.chip_cfg.gyro_fsr = 0xFF;
+	st.chip_cfg.accel_fsr = 0xFF;
+	st.chip_cfg.lpf = 0xFF;
+	st.chip_cfg.sample_rate = 0xFFFF;
+	st.chip_cfg.sensors = 0xFF;
+	st.chip_cfg.fifo_enable = 0xFF;
+	st.chip_cfg.clk_src = INV_CLK_PLL;
+	mpu_set_gyro_fsr(gyro_fsr);
+	mpu_set_accel_fsr(accel_fsr);
+	mpu_set_lpf(lpf);
+	mpu_set_sample_rate(sample_rate);
+	mpu_set_sensors(sensors_on);
+	mpu_configure_fifo(fifo_sensors);
+
+	if (dmp_was_on)
+		mpu_set_dmp_state(1);
+
+	return result;
+}
+#endif
+ /*
+ *  \n This function must be called with the device either face-up or face-down
+ *  (z-axis is parallel to gravity).
+ *  @param[out] gyro        Gyro biases in q16 format.
+ *  @param[out] accel       Accel biases (if applicable) in q16 format.
+ *  @return     Result mask (see above).
+ */
+int mpu_run_self_test(long *gyro, long *accel)
+{
+#ifdef MPU6050
+    const unsigned char tries = 2;
+    long gyro_st[3], accel_st[3];
+    unsigned char accel_result, gyro_result;
+#ifdef AK89xx_SECONDARY
+    unsigned char compass_result;
+#endif
+    int ii;
+#endif
+    int result;
+    unsigned char accel_fsr, fifo_sensors, sensors_on;
+    unsigned short gyro_fsr, sample_rate, lpf;
+    unsigned char dmp_was_on;
+
+    if (st.chip_cfg.dmp_on) {
+        mpu_set_dmp_state(0);
+        dmp_was_on = 1;
+    } else
+        dmp_was_on = 0;
+
+    /* Get initial settings. */
+    mpu_get_gyro_fsr(&gyro_fsr);
+    mpu_get_accel_fsr(&accel_fsr);
+    mpu_get_lpf(&lpf);
+    mpu_get_sample_rate(&sample_rate);
+    sensors_on = st.chip_cfg.sensors;
+    mpu_get_fifo_config(&fifo_sensors);
+
+    /* For older chips, the self-test will be different. */
+#if defined MPU6050
+    for (ii = 0; ii < tries; ii++)
+        if (!get_st_biases(gyro, accel, 0))
+            break;
+    if (ii == tries) {
+        /* If we reach this point, we most likely encountered an I2C error.
+         * We'll just report an error for all three sensors.
+         */
+        result = 0;
+        goto restore;
+    }
+    for (ii = 0; ii < tries; ii++)
+        if (!get_st_biases(gyro_st, accel_st, 1))
+            break;
+    if (ii == tries) {
+        /* Again, probably an I2C error. */
+        result = 0;
+        goto restore;
+    }
+    accel_result = accel_self_test(accel, accel_st);
+    gyro_result = gyro_self_test(gyro, gyro_st);
+
+    result = 0;
+    if (!gyro_result)
+        result |= 0x01;
+    if (!accel_result)
+        result |= 0x02;
+
+#ifdef AK89xx_SECONDARY
+    compass_result = compass_self_test();
+    if (!compass_result)
+        result |= 0x04;
+#else
+        result |= 0x04;
+#endif
+restore:
+#elif defined MPU6500
+    /* For now, this function will return a "pass" result for all three sensors
+     * for compatibility with current test applications.
+     */
+    get_st_biases(gyro, accel, 0);
+    result = 0x7;
+#endif
+    /* Set to invalid values to ensure no I2C writes are skipped. */
+    st.chip_cfg.gyro_fsr = 0xFF;
+    st.chip_cfg.accel_fsr = 0xFF;
+    st.chip_cfg.lpf = 0xFF;
+    st.chip_cfg.sample_rate = 0xFFFF;
+    st.chip_cfg.sensors = 0xFF;
+    st.chip_cfg.fifo_enable = 0xFF;
+    st.chip_cfg.clk_src = INV_CLK_PLL;
+    mpu_set_gyro_fsr(gyro_fsr);
+    mpu_set_accel_fsr(accel_fsr);
+    mpu_set_lpf(lpf);
+    mpu_set_sample_rate(sample_rate);
+    mpu_set_sensors(sensors_on);
+    mpu_configure_fifo(fifo_sensors);
+
+    if (dmp_was_on)
+        mpu_set_dmp_state(1);
+
+    return result;
+}
+
+/**
+ *  @brief      Write to the DMP memory.
+ *  This function prevents I2C writes past the bank boundaries. The DMP memory
+ *  is only accessible when the chip is awake.
+ *  @param[in]  mem_addr    Memory location (bank << 8 | start address)
+ *  @param[in]  length      Number of bytes to write.
+ *  @param[in]  data        Bytes to write to memory.
+ *  @return     0 if successful.
+ */
+int mpu_write_mem(unsigned short mem_addr, unsigned short length,
+        unsigned char *data)
+{
+    unsigned char tmp[2];
+
+    if (!data)
+        return -1;
+    if (!st.chip_cfg.sensors)
+        return -1;
+
+    tmp[0] = (unsigned char)(mem_addr >> 8);
+    tmp[1] = (unsigned char)(mem_addr & 0xFF);
+
+    /* Check bank boundaries. */
+    if (tmp[1] + length > st.hw->bank_size)
+        return -1;
+
+    if (mpu_hal_write(st.hw->addr, st.reg->bank_sel, 2, tmp))
+        return -1;
+    if (mpu_hal_write(st.hw->addr, st.reg->mem_r_w, length, data))
+        return -1;
+    return 0;
+}
+
+/**
+ *  @brief      Read from the DMP memory.
+ *  This function prevents I2C reads past the bank boundaries. The DMP memory
+ *  is only accessible when the chip is awake.
+ *  @param[in]  mem_addr    Memory location (bank << 8 | start address)
+ *  @param[in]  length      Number of bytes to read.
+ *  @param[out] data        Bytes read from memory.
+ *  @return     0 if successful.
+ */
+int mpu_read_mem(unsigned short mem_addr, unsigned short length,
+        unsigned char *data)
+{
+    unsigned char tmp[2];
+
+    if (!data)
+        return -1;
+    if (!st.chip_cfg.sensors)
+        return -1;
+
+    tmp[0] = (unsigned char)(mem_addr >> 8);
+    tmp[1] = (unsigned char)(mem_addr & 0xFF);
+
+    /* Check bank boundaries. */
+    if (tmp[1] + length > st.hw->bank_size)
+        return -1;
+
+    if (mpu_hal_write(st.hw->addr, st.reg->bank_sel, 2, tmp))
+        return -1;
+    if (mpu_hal_read(st.hw->addr, st.reg->mem_r_w, length, data))
+        return -1;
+    return 0;
+}
+
+/**
+ *  @brief      Load and verify DMP image.
+ *  @param[in]  length      Length of DMP image.
+ *  @param[in]  firmware    DMP code.
+ *  @param[in]  start_addr  Starting address of DMP code memory.
+ *  @param[in]  sample_rate Fixed sampling rate used when DMP is enabled.
+ *  @return     0 if successful.
+ */
+int mpu_load_firmware(unsigned short length, const unsigned char *firmware,
+    unsigned short start_addr, unsigned short sample_rate)
+{
+    unsigned short ii;
+    unsigned short this_write;
+    /* Must divide evenly into st.hw->bank_size to avoid bank crossings. */
+#define LOAD_CHUNK  (16)
+    static unsigned char cur[LOAD_CHUNK], tmp[2];
+
+    if (st.chip_cfg.dmp_loaded)
+        /* DMP should only be loaded once. */
+        return -1;
+
+    if (!firmware)
+        return -1;
+    for (ii = 0; ii < length; ii += this_write) {
+        this_write = min(LOAD_CHUNK, length - ii);
+        if (mpu_write_mem(ii, this_write, (unsigned char*)&firmware[ii]))
+            return -1;
+        if (mpu_read_mem(ii, this_write, cur))
+            return -1;
+        if (memcmp(firmware+ii, cur, this_write))
+            return -2;
+    }
+
+    /* Set program start address. */
+    tmp[0] = start_addr >> 8;
+    tmp[1] = start_addr & 0xFF;
+    if (mpu_hal_write(st.hw->addr, st.reg->prgm_start_h, 2, tmp))
+        return -1;
+
+    st.chip_cfg.dmp_loaded = 1;
+    st.chip_cfg.dmp_sample_rate = sample_rate;
+    return 0;
+}
+
+/**
+ *  @brief      Enable/disable DMP support.
+ *  @param[in]  enable  1 to turn on the DMP.
+ *  @return     0 if successful.
+ */
+int mpu_set_dmp_state(unsigned char enable)
+{
+    unsigned char tmp;
+    if (st.chip_cfg.dmp_on == enable)
+        return 0;
+
+    if (enable) {
+        if (!st.chip_cfg.dmp_loaded)
+            return -1;
+        /* Disable data ready interrupt. */
+        set_int_enable(0);
+        /* Disable bypass mode. */
+        mpu_set_bypass(0);
+        /* Keep constant sample rate, FIFO rate controlled by DMP. */
+        mpu_set_sample_rate(st.chip_cfg.dmp_sample_rate);
+        /* Remove FIFO elements. */
+        tmp = 0;
+        mpu_hal_write(st.hw->addr, 0x23, 1, &tmp);
+        st.chip_cfg.dmp_on = 1;
+        /* Enable DMP interrupt. */
+        set_int_enable(1);
+        mpu_reset_fifo();
+    } else {
+        /* Disable DMP interrupt. */
+        set_int_enable(0);
+        /* Restore FIFO settings. */
+        tmp = st.chip_cfg.fifo_enable;
+        mpu_hal_write(st.hw->addr, 0x23, 1, &tmp);
+        st.chip_cfg.dmp_on = 0;
+        mpu_reset_fifo();
+    }
+    return 0;
+}
+
+/**
+ *  @brief      Get DMP state.
+ *  @param[out] enabled 1 if enabled.
+ *  @return     0 if successful.
+ */
+int mpu_get_dmp_state(unsigned char *enabled)
+{
+    enabled[0] = st.chip_cfg.dmp_on;
+    return 0;
+}
+
+#ifdef AK89xx_SECONDARY
+/* This initialization is similar to the one in ak8975.c. */
+static int setup_compass(void)
+{
+    unsigned char data[4], akm_addr;
+
+#ifndef MPU_USE_SPI
+    mpu_set_bypass(1);
+
+    /* Find compass. Possible addresses range from 0x0C to 0x0F. */
+    for (akm_addr = 0x0C; akm_addr <= 0x0F; akm_addr++) {
+        int result;
+        result = mpu_hal_read(akm_addr, AKM_REG_WHOAMI, 1, data);
+        if (!result && (data[0] == AKM_WHOAMI))
+            break;
+    }
+
+    if (akm_addr > 0x0F) {
+        /* TODO: Handle this case in all compass-related functions. */
+        log_e("Compass not found.\n");
+        return -1;
+    }
+
+    st.chip_cfg.compass_addr = akm_addr;
+
+    data[0] = AKM_POWER_DOWN;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, data))
+        return -1;
+    delay_ms(1);
+
+    data[0] = AKM_FUSE_ROM_ACCESS;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, data))
+        return -1;
+    delay_ms(1);
+
+    /* Get sensitivity adjustment data from fuse ROM. */
+    if (mpu_hal_read(st.chip_cfg.compass_addr, AKM_REG_ASAX, 3, data))
+        return -1;
+    st.chip_cfg.mag_sens_adj[0] = (long)data[0] + 128;
+    st.chip_cfg.mag_sens_adj[1] = (long)data[1] + 128;
+    st.chip_cfg.mag_sens_adj[2] = (long)data[2] + 128;
+
+    data[0] = AKM_POWER_DOWN;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, data))
+        return -1;
+    delay_ms(1);
+
+    mpu_set_bypass(0);
+
+    /* Set up master mode, master clock, and ES bit. */
+    data[0] = 0x40;
+    if (mpu_hal_write(st.hw->addr, st.reg->i2c_mst, 1, data))
+        return -1;
+        
+#else
+	akm_addr = 0x0C;
+	st.chip_cfg.compass_addr = akm_addr;
+    
+    /* Set up master mode, master clock, and ES bit. */
+    data[0] = 0x40;
+    if (mpu_hal_write(st.hw->addr, st.reg->i2c_mst, 1, data))
+        return -1;
+    
+    /* Slave 0 reads from AKM adj registers. */
+    data[0] = BIT_I2C_READ | st.chip_cfg.compass_addr;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_addr, 1, data))
+        return -1;
+
+    /* Compass reads start at this register. */
+    data[0] = AKM_REG_ASAX;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_reg, 1, data))
+        return -1;
+
+    /* Enable slave 0, 8-byte reads. */
+    data[0] = BIT_SLAVE_EN | 3;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_ctrl, 1, data))
+        return -1;
+    
+    if (mpu_hal_read(st.hw->addr, st.reg->raw_compass, 3, data))
+        return -1;
+    
+    st.chip_cfg.mag_sens_adj[0] = (long)data[0] + 128;
+    st.chip_cfg.mag_sens_adj[1] = (long)data[1] + 128;
+    st.chip_cfg.mag_sens_adj[2] = (long)data[2] + 128;
+
+#endif
+
+    /* Slave 0 reads from AKM data registers. */
+    data[0] = BIT_I2C_READ | st.chip_cfg.compass_addr;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_addr, 1, data))
+        return -1;
+
+    /* Compass reads start at this register. */
+    data[0] = AKM_REG_ST1;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_reg, 1, data))
+        return -1;
+
+    /* Enable slave 0, 8-byte reads. */
+    data[0] = BIT_SLAVE_EN | 8;
+    if (mpu_hal_write(st.hw->addr, st.reg->s0_ctrl, 1, data))
+        return -1;
+
+    /* Slave 1 changes AKM measurement mode. */
+    data[0] = st.chip_cfg.compass_addr;
+    if (mpu_hal_write(st.hw->addr, st.reg->s1_addr, 1, data))
+        return -1;
+
+    /* AKM measurement mode register. */
+    data[0] = AKM_REG_CNTL;
+    if (mpu_hal_write(st.hw->addr, st.reg->s1_reg, 1, data))
+        return -1;
+
+    /* Enable slave 1, 1-byte writes. */
+    data[0] = BIT_SLAVE_EN | 1;
+    if (mpu_hal_write(st.hw->addr, st.reg->s1_ctrl, 1, data))
+        return -1;
+
+    /* Set slave 1 data. */
+    data[0] = AKM_SINGLE_MEASUREMENT;
+    if (mpu_hal_write(st.hw->addr, st.reg->s1_do, 1, data))
+        return -1;
+
+    /* Trigger slave 0 and slave 1 actions at each sample. */
+    data[0] = 0x03;
+    if (mpu_hal_write(st.hw->addr, st.reg->i2c_delay_ctrl, 1, data))
+        return -1;
+
+#ifdef MPU9150
+    /* For the MPU9150, the auxiliary I2C bus needs to be set to VDD. */
+    data[0] = BIT_I2C_MST_VDDIO;
+    if (mpu_hal_write(st.hw->addr, st.reg->yg_offs_tc, 1, data))
+        return -1;
+#endif
+
+    return 0;
+}
+#endif
+
+/**
+ *  @brief      Read raw compass data.
+ *  @param[out] data        Raw data in hardware units.
+ *  @param[out] timestamp   Timestamp in milliseconds. Null if not needed.
+ *  @return     0 if successful.
+ */
+int mpu_get_compass_reg(short *data, unsigned long *timestamp)
+{
+#ifdef AK89xx_SECONDARY
+    unsigned char tmp[9];
+
+    if (!(st.chip_cfg.sensors & INV_XYZ_COMPASS))
+        return -1;
+
+#ifdef AK89xx_BYPASS
+    if (mpu_hal_read(st.chip_cfg.compass_addr, AKM_REG_ST1, 8, tmp))
+        return -1;
+    tmp[8] = AKM_SINGLE_MEASUREMENT;
+    if (mpu_hal_write(st.chip_cfg.compass_addr, AKM_REG_CNTL, 1, tmp+8))
+        return -1;
+#else
+    if (mpu_hal_read(st.hw->addr, st.reg->raw_compass, 8, tmp))
+        return -1;
+#endif
+
+#if defined AK8975_SECONDARY
+    /* AK8975 doesn't have the overrun error bit. */
+    if (!(tmp[0] & AKM_DATA_READY))
+        return -2;
+    if ((tmp[7] & AKM_OVERFLOW) || (tmp[7] & AKM_DATA_ERROR))
+        return -3;
+#elif defined AK8963_SECONDARY
+    /* AK8963 doesn't have the data read error bit. */
+    if (!(tmp[0] & AKM_DATA_READY) || (tmp[0] & AKM_DATA_OVERRUN))
+        return -2;
+    if (tmp[7] & AKM_OVERFLOW)
+        return -3;
+#endif
+    data[0] = (tmp[2] << 8) | tmp[1];
+    data[1] = (tmp[4] << 8) | tmp[3];
+    data[2] = (tmp[6] << 8) | tmp[5];
+
+    data[0] = ((long)data[0] * st.chip_cfg.mag_sens_adj[0]) >> 8;
+    data[1] = ((long)data[1] * st.chip_cfg.mag_sens_adj[1]) >> 8;
+    data[2] = ((long)data[2] * st.chip_cfg.mag_sens_adj[2]) >> 8;
+
+    if (timestamp)
+        get_ms(timestamp);
+    return 0;
+#else
+    return -1;
+#endif
+}
+
+/**
+ *  @brief      Get the compass full-scale range.
+ *  @param[out] fsr Current full-scale range.
+ *  @return     0 if successful.
+ */
+int mpu_get_compass_fsr(unsigned short *fsr)
+{
+#ifdef AK89xx_SECONDARY
+    fsr[0] = st.hw->compass_fsr;
+    return 0;
+#else
+    return -1;
+#endif
+}
+
+/**
+ *  @brief      Enters LP accel motion interrupt mode.
+ *  The behaviour of this feature is very different between the MPU6050 and the
+ *  MPU6500. Each chip's version of this feature is explained below.
+ *
+ *  \n The hardware motion threshold can be between 32mg and 8160mg in 32mg
+ *  increments.
+ *
+ *  \n Low-power accel mode supports the following frequencies:
+ *  \n 1.25Hz, 5Hz, 20Hz, 40Hz
+ *
+ *  \n MPU6500:
+ *  \n Unlike the MPU6050 version, the hardware does not "lock in" a reference
+ *  sample. The hardware monitors the accel data and detects any large change
+ *  over a short period of time.
+ *
+ *  \n The hardware motion threshold can be between 4mg and 1020mg in 4mg
+ *  increments.
+ *
+ *  \n MPU6500 Low-power accel mode supports the following frequencies:
+ *  \n 1.25Hz, 2.5Hz, 5Hz, 10Hz, 20Hz, 40Hz, 80Hz, 160Hz, 320Hz, 640Hz
+ *
+ *  \n\n NOTES:
+ *  \n The driver will round down @e thresh to the nearest supported value if
+ *  an unsupported threshold is selected.
+ *  \n To select a fractional wake-up frequency, round down the value passed to
+ *  @e lpa_freq.
+ *  \n The MPU6500 does not support a delay parameter. If this function is used
+ *  for the MPU6500, the value passed to @e time will be ignored.
+ *  \n To disable this mode, set @e lpa_freq to zero. The driver will restore
+ *  the previous configuration.
+ *
+ *  @param[in]  thresh      Motion threshold in mg.
+ *  @param[in]  time        Duration in milliseconds that the accel data must
+ *                          exceed @e thresh before motion is reported.
+ *  @param[in]  lpa_freq    Minimum sampling rate, or zero to disable.
+ *  @return     0 if successful.
+ */
+int mpu_lp_motion_interrupt(unsigned short thresh, unsigned char time,
+    unsigned char lpa_freq)
+{
+
+#if defined MPU6500
+    unsigned char data[3];
+#endif
+    if (lpa_freq) {
+#if defined MPU6500
+    	unsigned char thresh_hw;
+
+        /* 1LSb = 4mg. */
+        if (thresh > 1020)
+            thresh_hw = 255;
+        else if (thresh < 4)
+            thresh_hw = 1;
+        else
+            thresh_hw = thresh >> 2;
+#endif
+
+        if (!time)
+            /* Minimum duration must be 1ms. */
+            time = 1;
+
+#if defined MPU6500
+        if (lpa_freq > 640)
+            /* At this point, the chip has not been re-configured, so the
+             * function can safely exit.
+             */
+            return -1;
+#endif
+
+        if (!st.chip_cfg.int_motion_only) {
+            /* Store current settings for later. */
+            if (st.chip_cfg.dmp_on) {
+                mpu_set_dmp_state(0);
+                st.chip_cfg.cache.dmp_on = 1;
+            } else
+                st.chip_cfg.cache.dmp_on = 0;
+            mpu_get_gyro_fsr(&st.chip_cfg.cache.gyro_fsr);
+            mpu_get_accel_fsr(&st.chip_cfg.cache.accel_fsr);
+            mpu_get_lpf(&st.chip_cfg.cache.lpf);
+            mpu_get_sample_rate(&st.chip_cfg.cache.sample_rate);
+            st.chip_cfg.cache.sensors_on = st.chip_cfg.sensors;
+            mpu_get_fifo_config(&st.chip_cfg.cache.fifo_sensors);
+        }
+
+#if defined MPU6500
+        /* Disable hardware interrupts. */
+        set_int_enable(0);
+
+        /* Enter full-power accel-only mode, no FIFO/DMP. */
+        data[0] = 0;
+        data[1] = 0;
+        data[2] = BIT_STBY_XYZG;
+        if (mpu_hal_write(st.hw->addr, st.reg->user_ctrl, 3, data))
+            goto lp_int_restore;
+
+        /* Set motion threshold. */
+        data[0] = thresh_hw;
+        if (mpu_hal_write(st.hw->addr, st.reg->motion_thr, 1, data))
+            goto lp_int_restore;
+
+        /* Set wake frequency. */
+        if (lpa_freq == 1)
+            data[0] = INV_LPA_1_25HZ;
+        else if (lpa_freq == 2)
+            data[0] = INV_LPA_2_5HZ;
+        else if (lpa_freq <= 5)
+            data[0] = INV_LPA_5HZ;
+        else if (lpa_freq <= 10)
+            data[0] = INV_LPA_10HZ;
+        else if (lpa_freq <= 20)
+            data[0] = INV_LPA_20HZ;
+        else if (lpa_freq <= 40)
+            data[0] = INV_LPA_40HZ;
+        else if (lpa_freq <= 80)
+            data[0] = INV_LPA_80HZ;
+        else if (lpa_freq <= 160)
+            data[0] = INV_LPA_160HZ;
+        else if (lpa_freq <= 320)
+            data[0] = INV_LPA_320HZ;
+        else
+            data[0] = INV_LPA_640HZ;
+        if (mpu_hal_write(st.hw->addr, st.reg->lp_accel_odr, 1, data))
+            goto lp_int_restore;
+
+        /* Enable motion interrupt (MPU6500 version). */
+        data[0] = BITS_WOM_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->accel_intel, 1, data))
+            goto lp_int_restore;
+
+        /* Enable cycle mode. */
+        data[0] = BIT_LPA_CYCLE;
+        if (mpu_hal_write(st.hw->addr, st.reg->pwr_mgmt_1, 1, data))
+            goto lp_int_restore;
+
+        /* Enable interrupt. */
+        data[0] = BIT_MOT_INT_EN;
+        if (mpu_hal_write(st.hw->addr, st.reg->int_enable, 1, data))
+            goto lp_int_restore;
+
+        st.chip_cfg.int_motion_only = 1;
+        return 0;
+#endif
+    } else {
+        /* Don't "restore" the previous state if no state has been saved. */
+        int ii;
+        char *cache_ptr = (char*)&st.chip_cfg.cache;
+        for (ii = 0; ii < sizeof(st.chip_cfg.cache); ii++) {
+            if (cache_ptr[ii] != 0)
+                goto lp_int_restore;
+        }
+        /* If we reach this point, motion interrupt mode hasn't been used yet. */
+        return -1;
+    }
+lp_int_restore:
+    /* Set to invalid values to ensure no I2C writes are skipped. */
+    st.chip_cfg.gyro_fsr = 0xFF;
+    st.chip_cfg.accel_fsr = 0xFF;
+    st.chip_cfg.lpf = 0xFF;
+    st.chip_cfg.sample_rate = 0xFFFF;
+    st.chip_cfg.sensors = 0xFF;
+    st.chip_cfg.fifo_enable = 0xFF;
+    st.chip_cfg.clk_src = INV_CLK_PLL;
+    mpu_set_sensors(st.chip_cfg.cache.sensors_on);
+    mpu_set_gyro_fsr(st.chip_cfg.cache.gyro_fsr);
+    mpu_set_accel_fsr(st.chip_cfg.cache.accel_fsr);
+    mpu_set_lpf(st.chip_cfg.cache.lpf);
+    mpu_set_sample_rate(st.chip_cfg.cache.sample_rate);
+    mpu_configure_fifo(st.chip_cfg.cache.fifo_sensors);
+
+    if (st.chip_cfg.cache.dmp_on)
+        mpu_set_dmp_state(1);
+
+#ifdef MPU6500
+    /* Disable motion interrupt (MPU6500 version). */
+    data[0] = 0;
+    if (mpu_hal_write(st.hw->addr, st.reg->accel_intel, 1, data))
+        goto lp_int_restore;
+#endif
+
+    st.chip_cfg.int_motion_only = 0;
+    return 0;
+}
+
+/**
+ *  @}
+ */
+