VEX Inertial Sensor C API¶

Functions ¶

imu_reset ¶

Calibrate IMU.

This takes approximately 2 seconds, and is blocking until the IMU status flag is set properly.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

int32_t imu_reset (uint8_t port)

#define IMU_PORT 1

void initialize() {
  imu_reset(IMU_PORT);
  int time = millis();
  int iter = 0;
  while (imu_get_status(IMU_PORT) & E_IMU_STATUS_CALIBRATING) {
    printf("IMU calibrating... %d\n", iter);
    iter += 10;
    delay(10);
  }
  // should print about 2000 ms
  printf("IMU is done calibrating (took %d ms)\n", iter - time);
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_reset_blocking ¶

Calibrate IMU.

This takes approximately 2 seconds, and is blocking until the IMU status flag is set properly.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::reset.

int32_t imu_reset_blocking (uint8_t port)

#define IMU_PORT 1

void initialize() {
  imu_reset_blocking(IMU_PORT);
  int time = millis();

  // should print about 2000 ms
  printf("IMU is done calibrating (took %d ms)\n", time);
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_get_rotation ¶

Get the total number of degrees the Inertial Sensor has spun about the z-axis.

This value is theoretically unbounded. Clockwise rotations are represented with positive degree values, while counterclockwise rotations are represented with negative ones.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_rotation.

double imu_get_rotation (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    printf("IMU get rotation: %f degrees\n", imu_get_rotation(IMU_PORT));
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The degree value or PROS_ERR_F if the operation failed, setting errno.

imu_get_heading ¶

Get the Inertial Sensor’s heading relative to the initial direction of its x-axis.

This value is bounded by [0,360). Clockwise rotations are represented with positive degree values, while counterclockwise rotations are represented with negative ones.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_heading.

double imu_get_heading (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    printf("IMU get heading: %f degrees\n", imu_get_heading(IMU_PORT));
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The degree value or PROS_ERR_F if the operation failed, setting errno.

imu_get_quaternion ¶

Get a quaternion representing the Inertial Sensor’s orientation.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_quaternion.

quaternion_s_t imu_get_quaternion (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    quaternion_s_t qt = imu_get_quaternion(IMU_PORT);
    printf("IMU quaternion: {x: %f, y: %f, z: %f, w: %f}\n", qt.x, qt.y, qt.z, qt.w);
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The quaternion representing the sensor’s orientation. If the operation failed, all the quaternion’s members are filled with PROS_ERR_F and errno is set.

imu_get_euler ¶

Get the Euler angles representing the Inertial Sensor’s orientation.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_euler.

euler_s_t imu_get_euler (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    euler_s_t eu = imu_get_euler(IMU_PORT);
    printf("IMU euler angles: {pitch: %f, roll: %f, yaw: %f}\n", eu.pitch, eu.roll, eu.yaw);
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The Euler angles representing the sensor’s orientation. If the operation failed, all the structure’s members are filled with PROS_ERR_F and errno is set.

imu_get_pitch ¶

Get the Inertial Sensor’s pitch angle bounded by (-180,180).

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_pitch.

double imu_get_pitch (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    printf("IMU pitch: %f\n", imu_get_pitch(IMU_PORT));
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The pitch angle, or PROS_ERR_F if the operation failed, setting errno.

imu_get_roll ¶

Get the Inertial Sensor’s roll angle bounded by (-180,180).

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_roll.

double imu_get_roll (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    printf("IMU roll: %f\n", imu_get_roll(IMU_PORT));
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The roll angle, or PROS_ERR_F if the operation failed, setting errno.

imu_get_yaw ¶

Get the Inertial Sensor’s yaw angle bounded by (-180,180).

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_yaw.

double imu_get_yaw (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    printf("IMU yaw: %f\n", imu_get_yaw(IMU_PORT));
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The yaw angle, or PROS_ERR_F if the operation failed, setting errno.

imu_get_gyro_rate ¶

Get the Inertial Sensor’s raw gyroscope values.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_gyro_rate.

imu_gyro_s_t imu_get_gyro_rate (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    imu_gyro_s_t gyro = imu_get_gyro_rate(IMU_PORT);
    printf("IMU gyro values: {x: %f, y: %f, z: %f}\n", gyro.x, gyro.y, gyro.z);
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The raw gyroscope values. If the operation failed, all the structure’s members are filled with PROS_ERR_F and errno is set.

—

imu_get_accel ¶

Get the Inertial Sensor’s raw accelerometer values.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is already calibrating.

Analogous to pros::Imu::get_accel.

imu_accel_s_t imu_get_accel (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    imu_accel_s_t accel = imu_get_accel(IMU_PORT);
    printf("IMU accel values: {x: %f, y: %f, z: %f}\n", accel.x, accel.y, accel.z);
    delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: The raw accelerometer values. If the operation failed, all the structure’s members are filled with PROS_ERR_F and errno is set.

—

imu_get_status ¶

Get the Inertial Sensor’s status.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.

Analogous to pros::Imu::get_status.

imu_status_e_t imu_get_status (uint8_t port)

#define IMU_PORT 1

void initialize() {
  imu_reset(IMU_PORT);
  int time = millis();
  int iter = 0;
  while (imu_get_status(IMU_PORT) & E_IMU_STATUS_CALIBRATING) {
    printf("IMU calibrating... %d\n", iter);
    iter += 10;
    delay(10);
  }
  // should print about 2000 ms
  printf("IMU is done calibrating (took %d ms)\n", iter - time);
}

Parameters
port	The V5 port number from (1-21)

Returns: The Inertial Sensor’s status code, or PROS_ERR if the operation failed, setting errno.

—

imu_get_physical_orientation ¶

Get the Inertial Sensor’s physical orientation.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.

Analogous to pros::Imu::get_status.

imu_orientation_e_t imu_get_physical_orientation (uint8_t port)

#define IMU_PORT 1

void initialize() {
  imu_reset(IMU_PORT);
    printf("IMU orientation %d\n", imu_get_physical_orientation(IMU_PORT));

}

Parameters
port	The V5 port number from (1-21)

Returns: The Inertial Sensor’s physical orientation, or PROS_ERR if the operation failed, setting errno.

—

imu_tare_heading ¶

Resets the current reading of the Inertial Sensor’s heading to zero.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare_heading.

int32_t imu_tare_heading (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_heading(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare_rotation ¶

Resets the current reading of the Inertial Sensor’s rotation to zero.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare_rotation.

int32_t imu_tare_rotation (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_rotation(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare_pitch ¶

Resets the current reading of the Inertial Sensor’s pitch to zero.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is stil calibrating.

Analogous to pros::Imu::tare_pitch.

int32_t imu_tare_pitch (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_pitch(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare_roll ¶

Resets the current reading of the Inertial Sensor’s roll to zero.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare_roll.

int32_t imu_tare_roll (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_roll(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare_yaw ¶

Resets the current reading of the Inertial Sensor’s yaw to zero.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare_yaw.

int32_t imu_tare_yaw (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_yaw(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare_euler ¶

Reset all 3 euler values of the Inertial Sensor to 0.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare_euler.

int32_t imu_tare_euler (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare_euler(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_tare ¶

Resets all 5 values of the Inertial Sensor to 0.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::tare.

int32_t imu_tare (uint8_t port)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_tare(IMU_PORT);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_euler ¶

Sets the current reading of the Inertial Sensor’s euler values to target euler values. Will default to +/- 180 if target exceeds +/- 180.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_euler.

int32_t imu_set_euler (uint8_t port, euler_s_t target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_euler(IMU_PORT, {45,45,45});
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target euler values for the euler values from 1-21

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_rotation ¶

Sets the current reading of the Inertial Sensor’s rotation to target value.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_rotation.

int32_t imu_set_rotation (uint8_t port, double target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_rotation(IMU_PORT, 45);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target value for the rotation value to be set to

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_heading ¶

Sets the current reading of the Inertial Sensor’s heading to target value Target will default to 360 if above 360 and default to 0 if below 0.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_heading.

int32_t imu_set_heading (uint8_t port, double target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_heading(IMU_PORT, 45);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target value for the heading value to be set to

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_pitch ¶

Sets the current reading of the Inertial Sensor’s pitch to target value Will default to +/- 180 if target exceeds +/- 180.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_pitch.

int32_t imu_set_pitch (uint8_t port, double target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_pitch(IMU_PORT, 45);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target value for the pitch value to be set to

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_roll ¶

Sets the current reading of the Inertial Sensor’s roll to target value Will default to +/- 180 if target exceeds +/- 180.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_roll.

int32_t imu_set_roll (uint8_t port, double target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_roll(IMU_PORT, 45);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target value for the roll value to be set to

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

imu_set_yaw ¶

Sets the current reading of the Inertial Sensor’s yaw to target value Will default to +/- 180 if target exceeds +/- 180.

This function uses the following values of errno when an error state is reached:

ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Inertial Sensor.
EAGAIN - The sensor is still calibrating.

Analogous to pros::Imu::set_yaw.

int32_t imu_set_yaw (uint8_t port, double target)

#define IMU_PORT 1

void opcontrol() {
  while (true) {
    if(controller_get_digital(CONTROLLER_MASTER, E_CONTROLLER_DIGITAL_X)){
      imu_set_yaw(IMU_PORT, 45);
    }
    pros::delay(20);
  }
}

Parameters
port	The V5 port number from (1-21)
target	The target value for the yaw value to be set to

Returns: 1 if the operation was successful or PROS_ERR if the operation failed, setting errno.

Enumerated Values ¶

imu_status_e_t ¶

Indicates IMU status.

typedef enum imu_status_e {
  E_IMU_STATUS_CALIBRATING = 0x01,
  E_IMU_STATUS_ERROR = 0xFF,
} imu_status_e_t;

Value
E_IMU_STATUS_CALIBRATING	The IMU is calibrating
E_IMU_STATUS_ERROR	Used to indicate that an error state was reached in the `imu_get_status` function

—

imu_orientation_e_t ¶

Indicates IMU physical orientation.

typedef enum imu_orientation_e {: E_IMU_Z_UP = 0, // IMU has the Z axis UP (VEX Logo facing DOWN) E_IMU_Z_DOWN = 1, // IMU has the Z axis DOWN (VEX Logo facing UP) E_IMU_X_UP = 2, // IMU has the X axis UP E_IMU_X_DOWN = 3, // IMU has the X axis DOWN E_IMU_Y_UP = 4, // IMU has the Y axis UP E_IMU_Y_DOWN = 5, // IMU has the Y axis DOWN

} imu_orientation_e_t;

Value
E_IMU_Z_UP	IMU has the Z axis UP (VEX Logo facing DOWN)
E_IMU_Z_DOWN	IMU has the Z axis DOWN (VEX Logo facing UP)
E_IMU_X_UP	IMU has the X axis UP
E_IMU_X_DOWN	IMU has the X axis DOWN
E_IMU_Y_UP	IMU has the Y axis UP
E_IMU_Y_DOWN	IMU has the Y axis DOWN

Structures ¶

imu_raw_s ¶

struct imu_raw_s {
  double x;
  double y;
  double z;
};

—

Typedefs ¶

quaternion_s_t ¶

typedef struct __attribute__((__packed__)) quaternion_s {
  double x;
  double y;
  double z;
  double w;
} quaternion_s_t;

—

euler_s_t ¶

typedef struct __attribute__((__packed__)) euler_s {
  double pitch;
  double roll;
  double yaw;
} euler_s_t;

—

imu_gyro_s_t ¶

typedef struct imu_raw_s imu_gyro_s_t;

—

imu_accel_s_t ¶

typedef struct imu_raw_s imu_accel_s_t;

—