VEEK-MT2 User Manual
19
www.terasic.com
July 4, 2016
3.5
Using the Gyroscope, Accelerometer and Magnetometer
The VEEK-MT2 is equipped with a Motion-Tracking device named MPU-9250. The MPU-9250 is a
9-axis Motion-Tracking device that combines a 3-axis gyroscope, 3-axis accelerometer and 3-axis
magnetometer. Detail features of these sensors are listed below:
Gyroscope
The MPU-9250 consists of three independent vibratory MEMS rate gyroscopes, which detect rotation
about the X-, Y-, and Z- Axes. When the gyros are rotated about any of the sense axes, the Coriolis
Effect causes a vibration that is detected by a capacitive pickoff. The resulting signal is amplified,
demodulated, and filtered to produce a voltage that is proportional to the angular rate. This voltage is
digitized using individual on-chip 16-bit Analog-to-Digital Converters (ADCs) to sample each axis. The
full-scale range of the gyro sensors may be digitally programmed to ±250, ±500, ±1000, or ±2000
degrees per second (dps). The ADC sample rate is programmable from 8,000 samples per second, down
to 3.9 samples per second, and user-selectable low-pass filters enable a wide range of cut-off
frequencies.
Accelerometer
The MPU-9250‟s 3-Axis accelerometer uses separate proof masses for each axis. Acceleration along a
particular axis induces displacement on the corresponding proof mass, and capacitive sensors detect the
displacement differentially. The MPU-9250‟s architecture reduces the accelerometers‟ susceptibility to
fabrication variations as well as to thermal drift. When the device is placed on a flat surface, it will
measure 0g on the X- and Y-axes and +1g on the Z-axis. The accelerometers‟ scale factor is calibrated at
the factory and is nominally independent of supply voltage. Each sensor has a dedicated sigma-delta
ADC for providing digital outputs. The full scale range of the digital output can be adjusted to ±2g, ±4g,
±8g, or ±16g.
Magnetometer
The 3-axis magnetometer uses highly sensitive Hall sensor technology. The magnetometer portion of the
IC incorporates magnetic sensors for detecting terrestrial magnetism in the X-, Y-, and Z- Axes, a sensor
driving circuit, a signal amplifier chain, and an arithmetic circuit for processing the signal from each
sensor. Each ADC has a 16-bit resolution and a full scale range of ±4800 μT.
Communication with all registers of the device is performed using either I2C at 400kHz or SPI at 1MHz.
For applications requiring faster communications, the sensor and interrupt registers may be read using
SPI at 20MHz. For more detailed information of better using this chip, please refer to its datasheet
which is available on manufacturer‟s website or under the /datasheet folder of the system CD.
gives the pin assignment information of the LCD touch panel. For more detailed information of better
using this chip, please refer to its datasheet which is available on manufacturer‟s website or under the
/datasheet folder of the system CD.
Summary of Contents for VEEK-MT2
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