Initialization and operation of sensor mpu6050 with nrf52840 development board

[MRK-196]

I want to be able to read the gyro and accelerometer values from the MPU6050 sensor.

As a base start I downloaded the  NRF5 SDK V15.3.0 and modified twi_sensor_pca10056 program using editor software Kielu5 to initialize the MPU6050. My current problem is that I am not getting the correct reading values from the sensor. The problem I think is coming from the MPU6050 initialization. Because the TWI supposed to work fine since its a working project and I also tested the UART by sending some initial test strings before operating.

I modified the project by including the following MPU related libraries in the main project:

• sensor_mpu6050.h
• sensor_mpu6050.c

I am connecting the SCL and SDL to the following respective board pins:

       SCL    = MPU6050_SCL_PIN,      // PIN 0.27
       SDA    = MPU6050_SDA_PIN,     // PIN 0.26

In the main.c , I am initializing the MPU and trying to read the MPU values and displaying them on a serial  terminal window using UART.

I am attaching the current working project main program and the added mpu libraries, the complete project is inside NRF5 v15.3.0 , I left it there since there are certain libraries that are spread across the SDK.

LINK TO PROJECT DOWNLOAD

PATH LINK TO CURRENT WORKING PROJECT :     nRF5_SDK_15.3.0_59ac345\examples\peripheral\twi_sensor\pca10056\blank\arm5_no_packs

I would appreciate someone's help since I'm new to this type of technology, don't hesitate to ask for more information.

[Simonr]

Hi

Can you show me how you initialize the MPU, and what you've put in the mpu.c and .h files? It's impossible to say what exactly is causing the UART not to print without knowing what's been done in the project.

Best regards,

Simon

[MRK-196]

CONTENT OF mpu.h :

#include "sensor_mpu6050.h"

void MPU6050_Init(void)
{
    uint8_t chipid = 0;
    uint8_t tmp = 0;

    //reset the chip
    tmp = 0x80;
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_PWR_MGMT_1, &tmp, 0x01);

    for(int i=0; i<30000; i++){__ASM("nop");}

    //wakeup the chip
    tmp = 0x00;
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_PWR_MGMT_1, &tmp, 0x01);

    //read chip id
    i2c_read(MPU6050_I2C_ADDRESS ,MPU6050_WHO_AM_I, &chipid, 0x01);

    for(int i=0; i<30000; i++){__ASM("nop");}
        
    //internal 20MHz oscillator
    tmp = 0x00;
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_PWR_MGMT_1, &tmp, 0x01);

    //read MPU6050_PWR_MGMT_2 register
    i2c_read(MPU6050_I2C_ADDRESS ,MPU6050_PWR_MGMT_2, &tmp, 0x01);

    //enable acc/gyro xyz
    tmp &= ~(0x38 | 0x07);
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_PWR_MGMT_2, &tmp, 0x01);

    //acc +-2g
    tmp = ( 0x00 << 3 ); 
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_ACCEL_CONFIG, &tmp, 0x01);
    
    //gyro 2000dps
    tmp = ( 0x03 << 3 );
    i2c_write(MPU6050_I2C_ADDRESS ,MPU6050_GYRO_CONFIG, &tmp, 0x01);
    
}

void MPU6050_GetAccData(float *acc)
{
    uint8_t tmp[6] = {0};
    int16_t tmp_int[3] = {0};

    i2c_read(MPU6050_I2C_ADDRESS ,MPU6050_ACCEL_XOUT_H, tmp, 0x06);
    tmp_int[0] = (int16_t)((tmp[0]<< 8) | tmp[1]);
    tmp_int[1] = (int16_t)((tmp[2]<< 8) | tmp[3]);
    tmp_int[2] = (int16_t)((tmp[4]<< 8) | tmp[5]);

    acc[0] = (float)(tmp_int[0]) * 0.00059854736328125f;
    acc[1] = (float)(tmp_int[1]) * 0.00059854736328125f;
    acc[2] = (float)(tmp_int[2]) * 0.00059854736328125f;
}

void MPU6050_GetGyroData(float *gyro)
{
    uint8_t tmp[6] = {0};
    int16_t tmp_int[3] = {0};

    i2c_read(MPU6050_I2C_ADDRESS ,MPU6050_GYRO_XOUT_H, tmp, 0x06);
    tmp_int[0] = (int16_t)((tmp[0]<< 8) | tmp[1]);
    tmp_int[1] = (int16_t)((tmp[2]<< 8) | tmp[3]);
    tmp_int[2] = (int16_t)((tmp[4]<< 8) | tmp[5]);

    gyro[0] = (float)(tmp_int[0]) * 0.001064225153455f;
    gyro[1] = (float)(tmp_int[1]) * 0.001064225153455f;
    gyro[2] = (float)(tmp_int[2]) * 0.001064225153455f;
}

CONTENT OF mpu.c :

#ifndef __MPU6050_H__
#define __MPU6050_H__

#include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"
#include "nrf_delay.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#define MPU6050_AUX_VDDIO          0x01   // R/W
#define MPU6050_SMPLRT_DIV         0x19   // R/W
#define MPU6050_CONFIG             0x1A   // R/W
#define MPU6050_GYRO_CONFIG        0x1B   // R/W
#define MPU6050_ACCEL_CONFIG       0x1C   // R/W
#define MPU6050_FF_THR             0x1D   // R/W
#define MPU6050_FF_DUR             0x1E   // R/W
#define MPU6050_MOT_THR            0x1F   // R/W
#define MPU6050_MOT_DUR            0x20   // R/W
#define MPU6050_ZRMOT_THR          0x21   // R/W
#define MPU6050_ZRMOT_DUR          0x22   // R/W
#define MPU6050_FIFO_EN            0x23   // R/W
#define MPU6050_I2C_MST_CTRL       0x24   // R/W
#define MPU6050_I2C_SLV0_ADDR      0x25   // R/W
#define MPU6050_I2C_SLV0_REG       0x26   // R/W
#define MPU6050_I2C_SLV0_CTRL      0x27   // R/W
#define MPU6050_I2C_SLV1_ADDR      0x28   // R/W
#define MPU6050_I2C_SLV1_REG       0x29   // R/W
#define MPU6050_I2C_SLV1_CTRL      0x2A   // R/W
#define MPU6050_I2C_SLV2_ADDR      0x2B   // R/W
#define MPU6050_I2C_SLV2_REG       0x2C   // R/W
#define MPU6050_I2C_SLV2_CTRL      0x2D   // R/W
#define MPU6050_I2C_SLV3_ADDR      0x2E   // R/W
#define MPU6050_I2C_SLV3_REG       0x2F   // R/W
#define MPU6050_I2C_SLV3_CTRL      0x30   // R/W
#define MPU6050_I2C_SLV4_ADDR      0x31   // R/W
#define MPU6050_I2C_SLV4_REG       0x32   // R/W
#define MPU6050_I2C_SLV4_DO        0x33   // R/W
#define MPU6050_I2C_SLV4_CTRL      0x34   // R/W
#define MPU6050_I2C_SLV4_DI        0x35   // R  
#define MPU6050_I2C_MST_STATUS     0x36   // R
#define MPU6050_INT_PIN_CFG        0x37   // R/W
#define MPU6050_INT_ENABLE         0x38   // R/W
#define MPU6050_INT_STATUS         0x3A   // R  
#define MPU6050_ACCEL_XOUT_H       0x3B   // R  
#define MPU6050_ACCEL_XOUT_L       0x3C   // R  
#define MPU6050_ACCEL_YOUT_H       0x3D   // R  
#define MPU6050_ACCEL_YOUT_L       0x3E   // R  
#define MPU6050_ACCEL_ZOUT_H       0x3F   // R  
#define MPU6050_ACCEL_ZOUT_L       0x40   // R  
#define MPU6050_TEMP_OUT_H         0x41   // R  
#define MPU6050_TEMP_OUT_L         0x42   // R  
#define MPU6050_GYRO_XOUT_H        0x43   // R  
#define MPU6050_GYRO_XOUT_L        0x44   // R  
#define MPU6050_GYRO_YOUT_H        0x45   // R  
#define MPU6050_GYRO_YOUT_L        0x46   // R  
#define MPU6050_GYRO_ZOUT_H        0x47   // R  
#define MPU6050_GYRO_ZOUT_L        0x48   // R  
#define MPU6050_EXT_SENS_DATA_00   0x49   // R  
#define MPU6050_EXT_SENS_DATA_01   0x4A   // R  
#define MPU6050_EXT_SENS_DATA_02   0x4B   // R  
#define MPU6050_EXT_SENS_DATA_03   0x4C   // R  
#define MPU6050_EXT_SENS_DATA_04   0x4D   // R  
#define MPU6050_EXT_SENS_DATA_05   0x4E   // R  
#define MPU6050_EXT_SENS_DATA_06   0x4F   // R  
#define MPU6050_EXT_SENS_DATA_07   0x50   // R  
#define MPU6050_EXT_SENS_DATA_08   0x51   // R  
#define MPU6050_EXT_SENS_DATA_09   0x52   // R  
#define MPU6050_EXT_SENS_DATA_10   0x53   // R  
#define MPU6050_EXT_SENS_DATA_11   0x54   // R  
#define MPU6050_EXT_SENS_DATA_12   0x55   // R  
#define MPU6050_EXT_SENS_DATA_13   0x56   // R  
#define MPU6050_EXT_SENS_DATA_14   0x57   // R  
#define MPU6050_EXT_SENS_DATA_15   0x58   // R  
#define MPU6050_EXT_SENS_DATA_16   0x59   // R  
#define MPU6050_EXT_SENS_DATA_17   0x5A   // R  
#define MPU6050_EXT_SENS_DATA_18   0x5B   // R  
#define MPU6050_EXT_SENS_DATA_19   0x5C   // R  
#define MPU6050_EXT_SENS_DATA_20   0x5D   // R  
#define MPU6050_EXT_SENS_DATA_21   0x5E   // R  
#define MPU6050_EXT_SENS_DATA_22   0x5F   // R  
#define MPU6050_EXT_SENS_DATA_23   0x60   // R  
#define MPU6050_MOT_DETECT_STATUS  0x61   // R  
#define MPU6050_I2C_SLV0_DO        0x63   // R/W
#define MPU6050_I2C_SLV1_DO        0x64   // R/W
#define MPU6050_I2C_SLV2_DO        0x65   // R/W
#define MPU6050_I2C_SLV3_DO        0x66   // R/W
#define MPU6050_I2C_MST_DELAY_CTRL 0x67   // R/W
#define MPU6050_SIGNAL_PATH_RESET  0x68   // R/W
#define MPU6050_MOT_DETECT_CTRL    0x69   // R/W
#define MPU6050_USER_CTRL          0x6A   // R/W
#define MPU6050_PWR_MGMT_1         0x6B   // R/W
#define MPU6050_PWR_MGMT_2         0x6C   // R/W
#define MPU6050_FIFO_COUNTH        0x72   // R/W
#define MPU6050_FIFO_COUNTL        0x73   // R/W
#define MPU6050_FIFO_R_W           0x74   // R/W
#define MPU6050_WHO_AM_I           0x75   // R

#define MPU6050_D0 0
#define MPU6050_D1 1
#define MPU6050_D2 2
#define MPU6050_D3 3
#define MPU6050_D4 4
#define MPU6050_D5 5
#define MPU6050_D6 6
#define MPU6050_D7 7
 
// AUX_VDDIO Register
//#define MPU6050_AUX_VDDIO MPU6050_D7  // I2C high: 1=VDD, 0=VLOGIC
 
// CONFIG Register
// DLPF is Digital Low Pass Filter for both gyro and accelerometers.
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_DLPF_CFG0     MPU6050_D0
#define MPU6050_DLPF_CFG1     MPU6050_D1
#define MPU6050_DLPF_CFG2     MPU6050_D2
#define MPU6050_EXT_SYNC_SET0 MPU6050_D3
#define MPU6050_EXT_SYNC_SET1 MPU6050_D4
#define MPU6050_EXT_SYNC_SET2 MPU6050_D5
 
// Combined definitions for the EXT_SYNC_SET values
#define MPU6050_EXT_SYNC_SET_0 (0)
#define MPU6050_EXT_SYNC_SET_1 (bit(MPU6050_EXT_SYNC_SET0))
#define MPU6050_EXT_SYNC_SET_2 (bit(MPU6050_EXT_SYNC_SET1))
#define MPU6050_EXT_SYNC_SET_3 (bit(MPU6050_EXT_SYNC_SET1)|bit(MPU6050_EXT_SYNC_SET0))
#define MPU6050_EXT_SYNC_SET_4 (bit(MPU6050_EXT_SYNC_SET2))
#define MPU6050_EXT_SYNC_SET_5 (bit(MPU6050_EXT_SYNC_SET2)|bit(MPU6050_EXT_SYNC_SET0))
#define MPU6050_EXT_SYNC_SET_6 (bit(MPU6050_EXT_SYNC_SET2)|bit(MPU6050_EXT_SYNC_SET1))
#define MPU6050_EXT_SYNC_SET_7 (bit(MPU6050_EXT_SYNC_SET2)|bit(MPU6050_EXT_SYNC_SET1)|bit(MPU6050_EXT_SYNC_SET0))
 
// Alternative names for the combined definitions.
#define MPU6050_EXT_SYNC_DISABLED     MPU6050_EXT_SYNC_SET_0
#define MPU6050_EXT_SYNC_TEMP_OUT_L   MPU6050_EXT_SYNC_SET_1
#define MPU6050_EXT_SYNC_GYRO_XOUT_L  MPU6050_EXT_SYNC_SET_2
#define MPU6050_EXT_SYNC_GYRO_YOUT_L  MPU6050_EXT_SYNC_SET_3
#define MPU6050_EXT_SYNC_GYRO_ZOUT_L  MPU6050_EXT_SYNC_SET_4
#define MPU6050_EXT_SYNC_ACCEL_XOUT_L MPU6050_EXT_SYNC_SET_5
#define MPU6050_EXT_SYNC_ACCEL_YOUT_L MPU6050_EXT_SYNC_SET_6
#define MPU6050_EXT_SYNC_ACCEL_ZOUT_L MPU6050_EXT_SYNC_SET_7
 
// Combined definitions for the DLPF_CFG values
#define MPU6050_DLPF_CFG_0 (0)
#define MPU6050_DLPF_CFG_1 (bit(MPU6050_DLPF_CFG0))
#define MPU6050_DLPF_CFG_2 (bit(MPU6050_DLPF_CFG1))
#define MPU6050_DLPF_CFG_3 (bit(MPU6050_DLPF_CFG1)|bit(MPU6050_DLPF_CFG0))
#define MPU6050_DLPF_CFG_4 (bit(MPU6050_DLPF_CFG2))
#define MPU6050_DLPF_CFG_5 (bit(MPU6050_DLPF_CFG2)|bit(MPU6050_DLPF_CFG0))
#define MPU6050_DLPF_CFG_6 (bit(MPU6050_DLPF_CFG2)|bit(MPU6050_DLPF_CFG1))
#define MPU6050_DLPF_CFG_7 (bit(MPU6050_DLPF_CFG2)|bit(MPU6050_DLPF_CFG1)|bit(MPU6050_DLPF_CFG0))
 
// Alternative names for the combined definitions
// This name uses the bandwidth (Hz) for the accelometer,
// for the gyro the bandwidth is almost the same.
#define MPU6050_DLPF_260HZ    MPU6050_DLPF_CFG_0
#define MPU6050_DLPF_184HZ    MPU6050_DLPF_CFG_1
#define MPU6050_DLPF_94HZ     MPU6050_DLPF_CFG_2
#define MPU6050_DLPF_44HZ     MPU6050_DLPF_CFG_3
#define MPU6050_DLPF_21HZ     MPU6050_DLPF_CFG_4
#define MPU6050_DLPF_10HZ     MPU6050_DLPF_CFG_5
#define MPU6050_DLPF_5HZ      MPU6050_DLPF_CFG_6
#define MPU6050_DLPF_RESERVED MPU6050_DLPF_CFG_7
 
// GYRO_CONFIG Register
// The XG_ST, YG_ST, ZG_ST are bits for selftest.
// The FS_SEL sets the range for the gyro.
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_FS_SEL0 MPU6050_D3
#define MPU6050_FS_SEL1 MPU6050_D4
#define MPU6050_ZG_ST   MPU6050_D5
#define MPU6050_YG_ST   MPU6050_D6
#define MPU6050_XG_ST   MPU6050_D7
 
// Combined definitions for the FS_SEL values
#define MPU6050_FS_SEL_0 (0)
#define MPU6050_FS_SEL_1 (bit(MPU6050_FS_SEL0))
#define MPU6050_FS_SEL_2 (bit(MPU6050_FS_SEL1))
#define MPU6050_FS_SEL_3 (bit(MPU6050_FS_SEL1)|bit(MPU6050_FS_SEL0))
 
// Alternative names for the combined definitions
// The name uses the range in degrees per second.
#define MPU6050_FS_SEL_250  MPU6050_FS_SEL_0
#define MPU6050_FS_SEL_500  MPU6050_FS_SEL_1
#define MPU6050_FS_SEL_1000 MPU6050_FS_SEL_2
#define MPU6050_FS_SEL_2000 MPU6050_FS_SEL_3
 
// ACCEL_CONFIG Register
// The XA_ST, YA_ST, ZA_ST are bits for selftest.
// The AFS_SEL sets the range for the accelerometer.
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_ACCEL_HPF0 MPU6050_D0
#define MPU6050_ACCEL_HPF1 MPU6050_D1
#define MPU6050_ACCEL_HPF2 MPU6050_D2
#define MPU6050_AFS_SEL0   MPU6050_D3
#define MPU6050_AFS_SEL1   MPU6050_D4
#define MPU6050_ZA_ST      MPU6050_D5
#define MPU6050_YA_ST      MPU6050_D6
#define MPU6050_XA_ST      MPU6050_D7
 
// Combined definitions for the ACCEL_HPF values
#define MPU6050_ACCEL_HPF_0 (0)
#define MPU6050_ACCEL_HPF_1 (bit(MPU6050_ACCEL_HPF0))
#define MPU6050_ACCEL_HPF_2 (bit(MPU6050_ACCEL_HPF1))
#define MPU6050_ACCEL_HPF_3 (bit(MPU6050_ACCEL_HPF1)|bit(MPU6050_ACCEL_HPF0))
#define MPU6050_ACCEL_HPF_4 (bit(MPU6050_ACCEL_HPF2))
#define MPU6050_ACCEL_HPF_7 (bit(MPU6050_ACCEL_HPF2)|bit(MPU6050_ACCEL_HPF1)|bit(MPU6050_ACCEL_HPF0))
 
// Alternative names for the combined definitions
// The name uses the Cut-off frequency.
#define MPU6050_ACCEL_HPF_RESET  MPU6050_ACCEL_HPF_0
#define MPU6050_ACCEL_HPF_5HZ    MPU6050_ACCEL_HPF_1
#define MPU6050_ACCEL_HPF_2_5HZ  MPU6050_ACCEL_HPF_2
#define MPU6050_ACCEL_HPF_1_25HZ MPU6050_ACCEL_HPF_3
#define MPU6050_ACCEL_HPF_0_63HZ MPU6050_ACCEL_HPF_4
#define MPU6050_ACCEL_HPF_HOLD   MPU6050_ACCEL_HPF_7
 
// Combined definitions for the AFS_SEL values
#define MPU6050_AFS_SEL_0 (0)
#define MPU6050_AFS_SEL_1 (bit(MPU6050_AFS_SEL0))
#define MPU6050_AFS_SEL_2 (bit(MPU6050_AFS_SEL1))
#define MPU6050_AFS_SEL_3 (bit(MPU6050_AFS_SEL1)|bit(MPU6050_AFS_SEL0))
 
// Alternative names for the combined definitions
// The name uses the full scale range for the accelerometer.
#define MPU6050_AFS_SEL_2G  MPU6050_AFS_SEL_0
#define MPU6050_AFS_SEL_4G  MPU6050_AFS_SEL_1
#define MPU6050_AFS_SEL_8G  MPU6050_AFS_SEL_2
#define MPU6050_AFS_SEL_16G MPU6050_AFS_SEL_3
 
// FIFO_EN Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_SLV0_FIFO_EN  MPU6050_D0
#define MPU6050_SLV1_FIFO_EN  MPU6050_D1
#define MPU6050_SLV2_FIFO_EN  MPU6050_D2
#define MPU6050_ACCEL_FIFO_EN MPU6050_D3
#define MPU6050_ZG_FIFO_EN    MPU6050_D4
#define MPU6050_YG_FIFO_EN    MPU6050_D5
#define MPU6050_XG_FIFO_EN    MPU6050_D6
#define MPU6050_TEMP_FIFO_EN  MPU6050_D7
 
// I2C_MST_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_MST_CLK0  MPU6050_D0
#define MPU6050_I2C_MST_CLK1  MPU6050_D1
#define MPU6050_I2C_MST_CLK2  MPU6050_D2
#define MPU6050_I2C_MST_CLK3  MPU6050_D3
#define MPU6050_I2C_MST_P_NSR MPU6050_D4
#define MPU6050_SLV_3_FIFO_EN MPU6050_D5
#define MPU6050_WAIT_FOR_ES   MPU6050_D6
#define MPU6050_MULT_MST_EN   MPU6050_D7
 
// Combined definitions for the I2C_MST_CLK
#define MPU6050_I2C_MST_CLK_0 (0)
#define MPU6050_I2C_MST_CLK_1  (bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_2  (bit(MPU6050_I2C_MST_CLK1))
#define MPU6050_I2C_MST_CLK_3  (bit(MPU6050_I2C_MST_CLK1)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_4  (bit(MPU6050_I2C_MST_CLK2))
#define MPU6050_I2C_MST_CLK_5  (bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_6  (bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK1))
#define MPU6050_I2C_MST_CLK_7  (bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK1)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_8  (bit(MPU6050_I2C_MST_CLK3))
#define MPU6050_I2C_MST_CLK_9  (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_10 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK1))
#define MPU6050_I2C_MST_CLK_11 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK1)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_12 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK2))
#define MPU6050_I2C_MST_CLK_13 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK0))
#define MPU6050_I2C_MST_CLK_14 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK1))
#define MPU6050_I2C_MST_CLK_15 (bit(MPU6050_I2C_MST_CLK3)|bit(MPU6050_I2C_MST_CLK2)|bit(MPU6050_I2C_MST_CLK1)|bit(MPU6050_I2C_MST_CLK0))
 
// Alternative names for the combined definitions
// The names uses I2C Master Clock Speed in kHz.
#define MPU6050_I2C_MST_CLK_348KHZ MPU6050_I2C_MST_CLK_0
#define MPU6050_I2C_MST_CLK_333KHZ MPU6050_I2C_MST_CLK_1
#define MPU6050_I2C_MST_CLK_320KHZ MPU6050_I2C_MST_CLK_2
#define MPU6050_I2C_MST_CLK_308KHZ MPU6050_I2C_MST_CLK_3
#define MPU6050_I2C_MST_CLK_296KHZ MPU6050_I2C_MST_CLK_4
#define MPU6050_I2C_MST_CLK_286KHZ MPU6050_I2C_MST_CLK_5
#define MPU6050_I2C_MST_CLK_276KHZ MPU6050_I2C_MST_CLK_6
#define MPU6050_I2C_MST_CLK_267KHZ MPU6050_I2C_MST_CLK_7
#define MPU6050_I2C_MST_CLK_258KHZ MPU6050_I2C_MST_CLK_8
#define MPU6050_I2C_MST_CLK_500KHZ MPU6050_I2C_MST_CLK_9
#define MPU6050_I2C_MST_CLK_471KHZ MPU6050_I2C_MST_CLK_10
#define MPU6050_I2C_MST_CLK_444KHZ MPU6050_I2C_MST_CLK_11
#define MPU6050_I2C_MST_CLK_421KHZ MPU6050_I2C_MST_CLK_12
#define MPU6050_I2C_MST_CLK_400KHZ MPU6050_I2C_MST_CLK_13
#define MPU6050_I2C_MST_CLK_381KHZ MPU6050_I2C_MST_CLK_14
#define MPU6050_I2C_MST_CLK_364KHZ MPU6050_I2C_MST_CLK_15
 
// I2C_SLV0_ADDR Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV0_RW MPU6050_D7
 
// I2C_SLV0_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV0_LEN0    MPU6050_D0
#define MPU6050_I2C_SLV0_LEN1    MPU6050_D1
#define MPU6050_I2C_SLV0_LEN2    MPU6050_D2
#define MPU6050_I2C_SLV0_LEN3    MPU6050_D3
#define MPU6050_I2C_SLV0_GRP     MPU6050_D4
#define MPU6050_I2C_SLV0_REG_DIS MPU6050_D5
#define MPU6050_I2C_SLV0_BYTE_SW MPU6050_D6
#define MPU6050_I2C_SLV0_EN      MPU6050_D7
 
// A mask for the length
#define MPU6050_I2C_SLV0_LEN_MASK 0x0F
 
// I2C_SLV1_ADDR Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV1_RW MPU6050_D7
 
// I2C_SLV1_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV1_LEN0    MPU6050_D0
#define MPU6050_I2C_SLV1_LEN1    MPU6050_D1
#define MPU6050_I2C_SLV1_LEN2    MPU6050_D2
#define MPU6050_I2C_SLV1_LEN3    MPU6050_D3
#define MPU6050_I2C_SLV1_GRP     MPU6050_D4
#define MPU6050_I2C_SLV1_REG_DIS MPU6050_D5
#define MPU6050_I2C_SLV1_BYTE_SW MPU6050_D6
#define MPU6050_I2C_SLV1_EN      MPU6050_D7
 
// A mask for the length
#define MPU6050_I2C_SLV1_LEN_MASK 0x0F
 
// I2C_SLV2_ADDR Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV2_RW MPU6050_D7
 
// I2C_SLV2_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV2_LEN0    MPU6050_D0
#define MPU6050_I2C_SLV2_LEN1    MPU6050_D1
#define MPU6050_I2C_SLV2_LEN2    MPU6050_D2
#define MPU6050_I2C_SLV2_LEN3    MPU6050_D3
#define MPU6050_I2C_SLV2_GRP     MPU6050_D4
#define MPU6050_I2C_SLV2_REG_DIS MPU6050_D5
#define MPU6050_I2C_SLV2_BYTE_SW MPU6050_D6
#define MPU6050_I2C_SLV2_EN      MPU6050_D7
 
// A mask for the length
#define MPU6050_I2C_SLV2_LEN_MASK 0x0F
 
// I2C_SLV3_ADDR Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV3_RW MPU6050_D7
 
// I2C_SLV3_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV3_LEN0    MPU6050_D0
#define MPU6050_I2C_SLV3_LEN1    MPU6050_D1
#define MPU6050_I2C_SLV3_LEN2    MPU6050_D2
#define MPU6050_I2C_SLV3_LEN3    MPU6050_D3
#define MPU6050_I2C_SLV3_GRP     MPU6050_D4
#define MPU6050_I2C_SLV3_REG_DIS MPU6050_D5
#define MPU6050_I2C_SLV3_BYTE_SW MPU6050_D6
#define MPU6050_I2C_SLV3_EN      MPU6050_D7
 
// A mask for the length
#define MPU6050_I2C_SLV3_LEN_MASK 0x0F
 
// I2C_SLV4_ADDR Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV4_RW MPU6050_D7
 
// I2C_SLV4_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_MST_DLY0     MPU6050_D0
#define MPU6050_I2C_MST_DLY1     MPU6050_D1
#define MPU6050_I2C_MST_DLY2     MPU6050_D2
#define MPU6050_I2C_MST_DLY3     MPU6050_D3
#define MPU6050_I2C_MST_DLY4     MPU6050_D4
#define MPU6050_I2C_SLV4_REG_DIS MPU6050_D5
#define MPU6050_I2C_SLV4_INT_EN  MPU6050_D6
#define MPU6050_I2C_SLV4_EN      MPU6050_D7
 
// A mask for the delay
#define MPU6050_I2C_MST_DLY_MASK 0x1F
 
// I2C_MST_STATUS Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV0_NACK MPU6050_D0
#define MPU6050_I2C_SLV1_NACK MPU6050_D1
#define MPU6050_I2C_SLV2_NACK MPU6050_D2
#define MPU6050_I2C_SLV3_NACK MPU6050_D3
#define MPU6050_I2C_SLV4_NACK MPU6050_D4
#define MPU6050_I2C_LOST_ARB  MPU6050_D5
#define MPU6050_I2C_SLV4_DONE MPU6050_D6
#define MPU6050_PASS_THROUGH  MPU6050_D7
 
// I2C_PIN_CFG Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_CLKOUT_EN       MPU6050_D0
#define MPU6050_I2C_BYPASS_EN   MPU6050_D1
#define MPU6050_FSYNC_INT_EN    MPU6050_D2
#define MPU6050_FSYNC_INT_LEVEL MPU6050_D3
#define MPU6050_INT_RD_CLEAR    MPU6050_D4
#define MPU6050_LATCH_INT_EN    MPU6050_D5
#define MPU6050_INT_OPEN        MPU6050_D6
#define MPU6050_INT_LEVEL       MPU6050_D7
 
// INT_ENABLE Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_DATA_RDY_EN    MPU6050_D0
#define MPU6050_I2C_MST_INT_EN MPU6050_D3
#define MPU6050_FIFO_OFLOW_EN  MPU6050_D4
#define MPU6050_ZMOT_EN        MPU6050_D5
#define MPU6050_MOT_EN         MPU6050_D6
#define MPU6050_FF_EN          MPU6050_D7
 
// INT_STATUS Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_DATA_RDY_INT   MPU6050_D0
#define MPU6050_I2C_MST_INT    MPU6050_D3
#define MPU6050_FIFO_OFLOW_INT MPU6050_D4
#define MPU6050_ZMOT_INT       MPU6050_D5
#define MPU6050_MOT_INT        MPU6050_D6
#define MPU6050_FF_INT         MPU6050_D7
 
// MOT_DETECT_STATUS Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_MOT_ZRMOT MPU6050_D0
#define MPU6050_MOT_ZPOS  MPU6050_D2
#define MPU6050_MOT_ZNEG  MPU6050_D3
#define MPU6050_MOT_YPOS  MPU6050_D4
#define MPU6050_MOT_YNEG  MPU6050_D5
#define MPU6050_MOT_XPOS  MPU6050_D6
#define MPU6050_MOT_XNEG  MPU6050_D7
 
// IC2_MST_DELAY_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_I2C_SLV0_DLY_EN MPU6050_D0
#define MPU6050_I2C_SLV1_DLY_EN MPU6050_D1
#define MPU6050_I2C_SLV2_DLY_EN MPU6050_D2
#define MPU6050_I2C_SLV3_DLY_EN MPU6050_D3
#define MPU6050_I2C_SLV4_DLY_EN MPU6050_D4
#define MPU6050_DELAY_ES_SHADOW MPU6050_D7
 
// SIGNAL_PATH_RESET Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_TEMP_RESET  MPU6050_D0
#define MPU6050_ACCEL_RESET MPU6050_D1
#define MPU6050_GYRO_RESET  MPU6050_D2
 
// MOT_DETECT_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_MOT_COUNT0      MPU6050_D0
#define MPU6050_MOT_COUNT1      MPU6050_D1
#define MPU6050_FF_COUNT0       MPU6050_D2
#define MPU6050_FF_COUNT1       MPU6050_D3
#define MPU6050_ACCEL_ON_DELAY0 MPU6050_D4
#define MPU6050_ACCEL_ON_DELAY1 MPU6050_D5
 
// Combined definitions for the MOT_COUNT
#define MPU6050_MOT_COUNT_0 (0)
#define MPU6050_MOT_COUNT_1 (bit(MPU6050_MOT_COUNT0))
#define MPU6050_MOT_COUNT_2 (bit(MPU6050_MOT_COUNT1))
#define MPU6050_MOT_COUNT_3 (bit(MPU6050_MOT_COUNT1)|bit(MPU6050_MOT_COUNT0))
 
// Alternative names for the combined definitions
#define MPU6050_MOT_COUNT_RESET MPU6050_MOT_COUNT_0
 
// Combined definitions for the FF_COUNT
#define MPU6050_FF_COUNT_0 (0)
#define MPU6050_FF_COUNT_1 (bit(MPU6050_FF_COUNT0))
#define MPU6050_FF_COUNT_2 (bit(MPU6050_FF_COUNT1))
#define MPU6050_FF_COUNT_3 (bit(MPU6050_FF_COUNT1)|bit(MPU6050_FF_COUNT0))
 
// Alternative names for the combined definitions
#define MPU6050_FF_COUNT_RESET MPU6050_FF_COUNT_0
 
// Combined definitions for the ACCEL_ON_DELAY
#define MPU6050_ACCEL_ON_DELAY_0 (0)
#define MPU6050_ACCEL_ON_DELAY_1 (bit(MPU6050_ACCEL_ON_DELAY0))
#define MPU6050_ACCEL_ON_DELAY_2 (bit(MPU6050_ACCEL_ON_DELAY1))
#define MPU6050_ACCEL_ON_DELAY_3 (bit(MPU6050_ACCEL_ON_DELAY1)|bit(MPU6050_ACCEL_ON_DELAY0))
 
// Alternative names for the ACCEL_ON_DELAY
#define MPU6050_ACCEL_ON_DELAY_0MS MPU6050_ACCEL_ON_DELAY_0
#define MPU6050_ACCEL_ON_DELAY_1MS MPU6050_ACCEL_ON_DELAY_1
#define MPU6050_ACCEL_ON_DELAY_2MS MPU6050_ACCEL_ON_DELAY_2
#define MPU6050_ACCEL_ON_DELAY_3MS MPU6050_ACCEL_ON_DELAY_3
 
// USER_CTRL Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_SIG_COND_RESET MPU6050_D0
#define MPU6050_I2C_MST_RESET  MPU6050_D1
#define MPU6050_FIFO_RESET     MPU6050_D2
#define MPU6050_I2C_IF_DIS     MPU6050_D4   // must be 0 for MPU-6050
#define MPU6050_I2C_MST_EN     MPU6050_D5
//#define MPU6050_FIFO_EN        MPU6050_D6
 
// PWR_MGMT_1 Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_CLKSEL0      MPU6050_D0
#define MPU6050_CLKSEL1      MPU6050_D1
#define MPU6050_CLKSEL2      MPU6050_D2
#define MPU6050_TEMP_DIS     MPU6050_D3    // 1: disable temperature sensor
#define MPU6050_CYCLE        MPU6050_D5    // 1: sample and sleep
#define MPU6050_SLEEP        MPU6050_D6    // 1: sleep mode
#define MPU6050_DEVICE_RESET MPU6050_D7    // 1: reset to default values
 
// Combined definitions for the CLKSEL
#define MPU6050_CLKSEL_0 (0)
#define MPU6050_CLKSEL_1 (bit(MPU6050_CLKSEL0))
#define MPU6050_CLKSEL_2 (bit(MPU6050_CLKSEL1))
#define MPU6050_CLKSEL_3 (bit(MPU6050_CLKSEL1)|bit(MPU6050_CLKSEL0))
#define MPU6050_CLKSEL_4 (bit(MPU6050_CLKSEL2))
#define MPU6050_CLKSEL_5 (bit(MPU6050_CLKSEL2)|bit(MPU6050_CLKSEL0))
#define MPU6050_CLKSEL_6 (bit(MPU6050_CLKSEL2)|bit(MPU6050_CLKSEL1))
#define MPU6050_CLKSEL_7 (bit(MPU6050_CLKSEL2)|bit(MPU6050_CLKSEL1)|bit(MPU6050_CLKSEL0))
 
// Alternative names for the combined definitions
#define MPU6050_CLKSEL_INTERNAL    MPU6050_CLKSEL_0
#define MPU6050_CLKSEL_X           MPU6050_CLKSEL_1
#define MPU6050_CLKSEL_Y           MPU6050_CLKSEL_2
#define MPU6050_CLKSEL_Z           MPU6050_CLKSEL_3
#define MPU6050_CLKSEL_EXT_32KHZ   MPU6050_CLKSEL_4
#define MPU6050_CLKSEL_EXT_19_2MHZ MPU6050_CLKSEL_5
#define MPU6050_CLKSEL_RESERVED    MPU6050_CLKSEL_6
#define MPU6050_CLKSEL_STOP        MPU6050_CLKSEL_7
 
// PWR_MGMT_2 Register
// These are the names for the bits.
// Use these only with the bit() macro.
#define MPU6050_STBY_ZG       MPU6050_D0
#define MPU6050_STBY_YG       MPU6050_D1
#define MPU6050_STBY_XG       MPU6050_D2
#define MPU6050_STBY_ZA       MPU6050_D3
#define MPU6050_STBY_YA       MPU6050_D4
#define MPU6050_STBY_XA       MPU6050_D5
#define MPU6050_LP_WAKE_CTRL0 MPU6050_D6
#define MPU6050_LP_WAKE_CTRL1 MPU6050_D7
 
// Combined definitions for the LP_WAKE_CTRL
#define MPU6050_LP_WAKE_CTRL_0 (0)
#define MPU6050_LP_WAKE_CTRL_1 (bit(MPU6050_LP_WAKE_CTRL0))
#define MPU6050_LP_WAKE_CTRL_2 (bit(MPU6050_LP_WAKE_CTRL1))
#define MPU6050_LP_WAKE_CTRL_3 (bit(MPU6050_LP_WAKE_CTRL1)|bit(MPU6050_LP_WAKE_CTRL0))
 
// Alternative names for the combined definitions
// The names uses the Wake-up Frequency.
#define MPU6050_LP_WAKE_1_25HZ MPU6050_LP_WAKE_CTRL_0
#define MPU6050_LP_WAKE_2_5HZ  MPU6050_LP_WAKE_CTRL_1
#define MPU6050_LP_WAKE_5HZ    MPU6050_LP_WAKE_CTRL_2
#define MPU6050_LP_WAKE_10HZ   MPU6050_LP_WAKE_CTRL_3
 
 
// Default I2C address for the MPU-6050 is 0x68.
// But only if the AD0 pin is low.
// Some sensor boards have AD0 high, and the
// I2C address thus becomes 0xD1.
#define MPU6050_I2C_ADDRESS 0xD0

void MPU6050_Init(void);
void MPU6050_GetAccData(float *acc);
void MPU6050_GetGyroData(float *gyro);

extern bool i2c_write( uint8_t device_address, uint8_t register_address, uint8_t *value, uint8_t number_of_bytes );
extern bool i2c_read( uint8_t device_address, uint8_t register_address, uint8_t *destination, uint8_t number_of_bytes );

#endif /* __MPU6050_H__ */

CONTENT OF main.c :

/**
 * Copyright (c) 2015 - 2019, Nordic Semiconductor ASA
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form, except as embedded into a Nordic
 *    Semiconductor ASA integrated circuit in a product or a software update for
 *    such product, must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
 * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. This software, with or without modification, must only be used with a
 *    Nordic Semiconductor ASA integrated circuit.
 *
 * 5. Any software provided in binary form under this license must not be reverse
 *    engineered, decompiled, modified and/or disassembled.
 *
 * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
/** @file
 * @defgroup tw_sensor_example main.c
 * @{
 * @ingroup nrf_twi_example
 * @brief TWI Sensor Example main file.
 *
 * This file contains the source code for a sample application using TWI.
 *
 */

#include <stdio.h>
#include "boards.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_drv_twi.h"
#include "nrf_delay.h"


#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#include "sensor_mpu6050.h"
#include "nrf_pwr_mgmt.h"
#include "app_uart.h"

/* TWI instance ID. */
#define TWI_INSTANCE_ID     0

/* Common addresses definition for temperature sensor. */
#define LM75B_ADDR          (0x90U >> 1)  // 1001 0000 >> 1 =  0100 1000

#define LM75B_REG_TEMP      0x00U
#define LM75B_REG_CONF      0x01U
#define LM75B_REG_THYST     0x02U
#define LM75B_REG_TOS       0x03U

/* Mode for LM75B. */
#define NORMAL_MODE 0U

/* Common addresses definition for MPU6050. */
#define MPU6050_ADDR       	0x


float MPU6050_Acc[3] = {0};
float MPU6050_Gyro[3] = {0};

bool i2c_write( uint8_t device_address, uint8_t register_address, uint8_t *value, uint8_t number_of_bytes );
bool i2c_read( uint8_t device_address, uint8_t register_address, uint8_t *destination, uint8_t number_of_bytes );


#define C_Output_Acc                     0x61    // "a" Command: Output acc data
#define C_Output_Gyro		                 0x67    // "g" Command: Output gyro data

#define Output_Select_Gyro        			 0x01
#define Output_Select_Acc         			 0x00

#define Default_Zero										 0x00

uint8_t StringSelect;                           //  1 = Output Gryo, 0 = Output Acc
char printf_buffer[256];                        //  Output Buffer
uint16_t length;                                //  Output Buffer Length





/* Indicates if operation on TWI has ended. */
static volatile bool m_xfer_done = false;

/* TWI instance. */
static const nrf_drv_twi_t m_twi = NRF_DRV_TWI_INSTANCE(TWI_INSTANCE_ID);

/* Buffer for samples read from temperature sensor. */
static uint8_t m_sample;

/**
 * @brief Function for setting active mode on MMA7660 accelerometer.
 */
void LM75B_set_mode(void)
{
    ret_code_t err_code;

    /* Writing to LM75B_REG_CONF "0" set temperature sensor in NORMAL mode. */
    uint8_t reg[2] = {LM75B_REG_CONF, NORMAL_MODE};
    err_code = nrf_drv_twi_tx(&m_twi, LM75B_ADDR, reg, sizeof(reg), false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);

    /* Writing to pointer byte. */
    reg[0] = LM75B_REG_TEMP;
    m_xfer_done = false;
    err_code = nrf_drv_twi_tx(&m_twi, LM75B_ADDR, reg, 1, false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);
}

/**
 * @brief Function for handling data from temperature sensor.
 *
 * @param[in] temp          Temperature in Celsius degrees read from sensor.
 */
__STATIC_INLINE void data_handler(uint8_t temp)
{
    NRF_LOG_INFO("Temperature: %d Celsius degrees.", temp);
}

/**
 * @brief TWI events handler.
 */
void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{
    switch (p_event->type)
    {
        case NRF_DRV_TWI_EVT_DONE:
            if (p_event->xfer_desc.type == NRF_DRV_TWI_XFER_RX)
            {
                data_handler(m_sample);
            }
            m_xfer_done = true;
            break;
        default:
            break;
    }
}

/**
 * @brief UART initialization.
 */
void twi_init (void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_MPU6050_config = {
       .scl                = MPU6050_SCL_PIN, // PIN 0.27
       .sda                = MPU6050_SDA_PIN, // PIN 0.26
       .frequency          = NRF_DRV_TWI_FREQ_100K, 
       .interrupt_priority = APP_IRQ_PRIORITY_LOW,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_MPU6050_config, twi_handler, NULL);
    APP_ERROR_CHECK(err_code);

    nrf_drv_twi_enable(&m_twi);
}

/**
 * @brief Function for reading data from temperature sensor.
 */
static void read_sensor_data()
{
    m_xfer_done = false;

    /* Read 1 byte from the specified address - skip 3 bits dedicated for fractional part of temperature. */
    ret_code_t err_code = nrf_drv_twi_rx(&m_twi, LM75B_ADDR, &m_sample, sizeof(m_sample));
    APP_ERROR_CHECK(err_code);
}

/**
 * @brief Function for writing data from MPU6050 sensor.
 */
bool i2c_write(uint8_t device_address, uint8_t register_address, uint8_t *value, uint8_t number_of_bytes )
{  
     uint8_t w_data[number_of_bytes+1], i;
   
     w_data[0] = register_address;
     for ( i = 0 ; i < number_of_bytes ; i++ )
     {
        w_data[i+1] = value[i];  
     }

     nrf_drv_twi_tx(&m_twi, (device_address)>>1, w_data, number_of_bytes+1, false);
     
     return true;
}
/**
 * @brief Function for reading data from MPU6050 sensor.
 */
bool i2c_read(uint8_t device_address, uint8_t register_address, uint8_t * destination, uint8_t number_of_bytes)
{    
     nrf_drv_twi_tx(&m_twi, (device_address)>>1, &register_address, 1, true);
     nrf_drv_twi_rx(&m_twi, (device_address)>>1, destination, number_of_bytes);
       
     return true;  
}


/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    UNUSED_RETURN_VALUE(NRF_LOG_PROCESS());
    nrf_pwr_mgmt_run();
}





/**
 * @brief Function for main application entry.
 */
int main(void)
{
    APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_LOG_INFO("\r\nTWI example started");
    NRF_LOG_FLUSH();
	

	
	twi_init();					//I2C Init
	nrf_delay_ms(50);
    MPU6050_Init();			//Sensor Init
	
    
    
	
    StringSelect = 1;
    length = Default_Zero;
    // Enter main loop.
    for (;;)
    {
        memset(printf_buffer, 0x00, sizeof(printf_buffer));
        if(StringSelect == 1)
		{					//if(StringSelect == Output_Select_Gyro)
		snprintf(printf_buffer, 100, "G: %.1f; %.1f; %.1f", MPU6050_Gyro[0], MPU6050_Gyro[1], MPU6050_Gyro[2]);
		}
        else{
            snprintf(printf_buffer,100, "A: %.1f; %.1f; %.1f", MPU6050_Acc[0], MPU6050_Acc[1], MPU6050_Acc[2]);
			}
        length = strlen(printf_buffer);
        //uint32_t err_code = ble_nus_data_send(&m_nus, (uint8_t *)printf_buffer, &length, m_conn_handle);
        nrf_delay_ms(500);
        MPU6050_GetAccData(MPU6050_Acc);
        nrf_delay_ms(50);
        MPU6050_GetGyroData(MPU6050_Gyro);
        //idle_state_handle();
		NRF_LOG_FLUSH();
    }
		
}

/** @} */

[Simonr]

Hi

I tried running your project, and I have no problems printing to UART. I'm using an nRF52840DK with no peripheral attached and print to a PuTTY terminal, and the terminal keeps printing these values:

TWI example started CLARK.
<info> app:
im here 4.
<info> app:
im here 5.
<info> app:
 im here 6.
<info> app:
 cx is 7.
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
im here 5.
<info> app:
 im here 6.
<info> app:
 cx is 7.
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
im here 5.
<info> app:
 im here 6.
<info> app:
 cx is 7.
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
im here 5.
<info> app:
 im here 6.
<info> app:
 cx is 7.
<info> app:
 gyro is 0
<info> app:
 gyro is 0
<info> app:
 gyro is 0

I used SEGGER Embedded Studios to build and run your project, and all I had to do was to add the header files to the preprocessor defines as described here. So there doesn't seem to be any issues with how you initialize UART on the nRF side. Is the problem that you're not able to get the correct values from the MPU6050 or that the UART doesn't print at all for you?

Best regards,

Simon

[MRK-196]

Thanks for taking the time to test out my code, but my problem is that I am not getting the correct values from the mpu6050 sensor.

[Simonr]

Hi

I found this GitHub repository, which uses its own MPU library compatible with SDK14.2 of nRF5 series devices. Please take a look at that to see if you can find what's incorrect about your sensor settings.

Best regards,

Simon