MPU9250

Arduino library for MPU9250 Nine-Axis (Gyro + Accelerometer + Compass) MEMS MotionTracking™ Device

This library is based on the great work by kriswiner, and re-writen for the simple usage.

Usage

Simple Measurement

#include "MPU9250.h"

MPU9250 mpu; // You can also use MPU9255 as is

void setup() {
    Serial.begin(115200);
    Wire.begin();
    delay(2000);

    mpu.setup(0x68);  // change to your own address
}

void loop() {
    if (mpu.update()) {
        Serial.print(mpu.getYaw()); Serial.print(", ");
        Serial.print(mpu.getPitch()); Serial.print(", ");
        Serial.println(mpu.getRoll());
    }
}

Calibration

• accel/gyro/mag offsets are NOT stored to register if the MPU has powered off (app note)
• need to set all offsets at every bootup by yourself (or calibrate at every bootup)
• device should be stay still during accel/gyro calibration
• round device around during mag calibration

#include "MPU9250.h"

MPU9250 mpu; // You can also use MPU9255 as is

void setup() {
    Serial.begin(115200);
    Wire.begin();
    delay(2000);

    mpu.setup(0x68);  // change to your own address

    delay(5000);

    // calibrate anytime you want to
    mpu.calibrateAccelGyro();
    mpu.calibrateMag();
}

void loop() { }

Coordinate

The coordinate of quaternion and roll/pitch/yaw angles are basedd on airplane coordinate (Right-Handed, X-forward, Z-down). On the other hand, the coordinate of euler angle is based on the axes of acceleration and gyro sensors (Right-Handed, X-forward, Z-up).Please use getEulerX/Y/Z() for euler angles and getRoll/Pitch/Yaw() for airplane coordinate angles.

Other Settings

I2C Address

You must set your own address based on A0, A1, A2 setting as:

mpu.setup(0x70);

Customize MPU9250 Configuration

You can set your own setting using MPU9250Setting struct as:

MPU9250Setting setting;
setting.accel_fs_sel = ACCEL_FS_SEL::A16G;
setting.gyro_fs_sel = GYRO_FS_SEL::G2000DPS;
setting.mag_output_bits = MAG_OUTPUT_BITS::M16BITS;
setting.fifo_sample_rate = FIFO_SAMPLE_RATE::SMPL_200HZ;
setting.gyro_fchoice = 0x03;
setting.gyro_dlpf_cfg = GYRO_DLPF_CFG::DLPF_41HZ;
setting.accel_fchoice = 0x01;
setting.accel_dlpf_cfg = ACCEL_DLPF_CFG::DLPF_45HZ;

mpu.setup(0x68, setting);

See custom_setting.ino example for detail.

List of Settings

enum class ACCEL_FS_SEL { A2G, A4G, A8G, A16G };
enum class GYRO_FS_SEL { G250DPS, G500DPS, G1000DPS, G2000DPS };
enum class MAG_OUTPUT_BITS { M14BITS, M16BITS };

enum class FIFO_SAMPLE_RATE : uint8_t {
    SMPL_1000HZ,
    SMPL_500HZ,
    SMPL_333HZ,
    SMPL_250HZ,
    SMPL_200HZ,
    SMPL_167HZ,
    SMPL_143HZ,
    SMPL_125HZ,
};

enum class GYRO_DLPF_CFG : uint8_t {
    DLPF_250HZ,
    DLPF_184HZ,
    DLPF_92HZ,
    DLPF_41HZ,
    DLPF_20HZ,
    DLPF_10HZ,
    DLPF_5HZ,
    DLPF_3600HZ,
};

enum class ACCEL_DLPF_CFG : uint8_t {
    DLPF_218HZ_0,
    DLPF_218HZ_1,
    DLPF_99HZ,
    DLPF_45HZ,
    DLPF_21HZ,
    DLPF_10HZ,
    DLPF_5HZ,
    DLPF_420HZ,
};

struct MPU9250Setting {
    ACCEL_FS_SEL     accel_fs_sel {ACCEL_FS_SEL::A16G};
    GYRO_FS_SEL      gyro_fs_sel {GYRO_FS_SEL::G2000DPS};
    MAG_OUTPUT_BITS  mag_output_bits {MAG_OUTPUT_BITS::M16BITS};
    FIFO_SAMPLE_RATE fifo_sample_rate {FIFO_SAMPLE_RATE::SMPL_200HZ};
    uint8_t          gyro_fchoice {0x03};
    GYRO_DLPF_CFG    gyro_dlpf_cfg {GYRO_DLPF_CFG::DLPF_41HZ};
    uint8_t          accel_fchoice {0x01};
    ACCEL_DLPF_CFG   accel_dlpf_cfg {ACCEL_DLPF_CFG::DLPF_45HZ};
};

Magnetic Declination

Magnetic declination should be set depending on where you are to get accurate data. To set it, use this method.

mpu.setMagneticDeclination(value);

You can find magnetic declination in your city here.

For more details, see wiki.

Quaternion Filter

You can choose quaternion filter using void selectFilter(QuatFilterSel sel). Available quaternion filters are listed below.

enum class QuatFilterSel {
    NONE,
    MADGWICK, // default
    MAHONY,
};

You can also change the calculate iterations for the filter as follows. The default value is 1. Generally 10-20 is good for stable yaw estimation. Please see this discussion for the detail.

mpu.setFilterIterations(10);

Other I2C library

You can use other I2C library e.g. SoftWire.

MPU9250_<SoftWire> mpu;
SoftWire sw(SDA, SCL);

// you need setting struct
MPU9250Setting setting;

// in setup()
mpu.setup(0x70, setting, sw);

About I2C Errors

Sometimes this library shows the I2C error number if your connection is not correct. It's based on the I2C error number which is reported by the Wire.endTransmission(). It returns following number based on the result of I2C data transmission.

0:success 1:data too long to fit in transmit buffer 2:received NACK on transmit of address 3:received NACK on transmit of data 4:other error

If you have such errors, please check your hardware connection and I2C address setting first. Please refer Wire.endTransmission() reference for these errors, and section 2.3 of this explanation for ACK and NACK.

APIs

bool setup(const uint8_t addr, const MPU9250Setting& setting, WireType& w = Wire);
void verbose(const bool b);
void ahrs(const bool b);
void calibrateAccelGyro();
void calibrateMag();
bool isConnected();
bool isConnectedMPU9250();
bool isConnectedAK8963();
bool available();
bool update();

float getRoll() const;
float getPitch() const;
float getYaw() const;

float getEulerX() const;
float getEulerY() const;
float getEulerZ() const;

float getQuaternionX() const;
float getQuaternionY() const;
float getQuaternionZ() const;
float getQuaternionW() const;

float getAcc(const uint8_t i) const;
float getGyro(const uint8_t i) const;
float getMag(const uint8_t i) const;
float getLinearAcc(const uint8_t i) const;

float getAccX() const;
float getAccY() const;
float getAccZ() const;
float getGyroX() const;
float getGyroY() const;
float getGyroZ() const;
float getMagX() const;
float getMagY() const;
float getMagZ() const;
float getLinearAccX() const;
float getLinearAccY() const;
float getLinearAccZ() const;

float getAccBias(const uint8_t i) const;
float getGyroBias(const uint8_t i) const;
float getMagBias(const uint8_t i) const;
float getMagScale(const uint8_t i) const;

float getAccBiasX() const;
float getAccBiasY() const;
float getAccBiasZ() const;
float getGyroBiasX() const;
float getGyroBiasY() const;
float getGyroBiasZ() const;
float getMagBiasX() const;
float getMagBiasY() const;
float getMagBiasZ() const;
float getMagScaleX() const;
float getMagScaleY() const;
float getMagScaleZ() const;

float getTemperature() const;

void setAccBias(const float x, const float y, const float z);
void setGyroBias(const float x, const float y, const float z);
void setMagBias(const float x, const float y, const float z);
void setMagScale(const float x, const float y, const float z);
void setMagneticDeclination(const float d);

void selectFilter(QuatFilterSel sel);
void setFilterIterations(const size_t n);

bool selftest();

License

MIT

Acknowledgments / Contributor

• Yuta Asai