Accelerometer Advanced Usage

Raw And Translated Data

Raw and translated acceleration datas are available. Calling mpu925x_get_acceleration function also calls mpu925x_get_acceleration_raw function internally. Both functions stores data in given mpu925x_t struct.

void mpu925x_get_acceleration(mpu925x_t *mpu925x)

Get acceleration in G’s.

See also

mpu925x_get_acceleration_raw

Parameters

mpu925x – MPU-925X struct pointer.

void mpu925x_get_acceleration_raw(mpu925x_t *mpu925x)

Get raw acceleration data.

See also

mpu925x_get_acceleration

Parameters

mpu925x – MPU-925X struct pointer.

Full-Scale Select

One can set accelerometer full-scale range of 2g, 4g, 8g and 16g.

void mpu925x_set_accelerometer_scale(mpu925x_t *mpu925x, mpu925x_accelerometer_scale scale)

Set accelerometer full-scale range.

Parameters

  • mpu925x – MPU-925X struct pointer.

  • scale – Accelerometer full-scale range to be set.

enum mpu925x_accelerometer_scale

Accelerometer full-scale ranges.

Values:

enumerator mpu925x_2g
enumerator mpu925x_4g
enumerator mpu925x_8g
enumerator mpu925x_16g

Digital Low Pass Filter

One can enable hardware digital low pass filter. Look datasheet for more info.

void mpu925x_set_accelerometer_dlpf(mpu925x_t *mpu925x, uint8_t a_fchoice, uint8_t dlpf)

Set accelerometer digital low pass filter setting.

Parameters

  • mpu925x – MPU-925X struct pointer.

  • a_fchoice – Accelerometer fchoice bit.

  • dlpf – Digital low pass filter choice.

Offset Cancellation

Offset cancellation consist 2 steps: Getting and setting offset cancellation values. While getting offset cancellation values, sensor must stand still. Also orientation of sensor is very important. Set orientation of sensor with .sensor_settings.orientation variable in mpu925x_t struct.

enum mpu925x_orientation

Orientation of the sensor.

Values:

enumerator mpu925x_x_plus
enumerator mpu925x_x_minus
enumerator mpu925x_y_plus
enumerator mpu925x_y_minus
enumerator mpu925x_z_plus
enumerator mpu925x_z_minus
void mpu925x_get_accelerometer_offset(mpu925x_t *mpu925x, uint16_t sampling_amount, int16_t *offset)

Get accelerometer offset cancellation value.

Parameters

  • mpu925x – MPU-925X struct pointer.

  • sampling_amount – Sampling amount for acceleration values.

  • offset – 3d array which will hold accelerometer offset cancellation values.

void mpu925x_set_accelerometer_offset(mpu925x_t *mpu925x, int16_t *offset)

Set accelerometer offset cancellation value.

Parameters

  • mpu925x – MPU-925X struct pointer.

  • offset – 3d array which holds accelerometer offset cancellation values.

One can use these two methods to get and set offset values or call one unified function which does 2 of them at once.

void mpu925x_accelerometer_offset_cancellation(mpu925x_t *mpu925x, uint16_t sampling_amount)

Get and set accelerometer offset cancellation values.

See also

mpu925x_get_accelerometer_offset

See also

mpu925x_set_accelerometer_offset

Parameters

  • mpu925x – MPU-925X struct pointer.

  • sampling_amount – Sampling amount for acceleration values.

Example Code
mpu925x.settings.orientation = mpu925x_y_plus; // Depends on how sensor is mounted.
// Sensor must stand still while offset cancellation.
mpu925x_accelerometer_offset_cancellation(&mpu925x, 200);