PNI SENtral MandM - Manual (Page 4)

PNI Sensor Corporation Doc #1020129 revE
SENtral M&M Technical Datasheet Page 3
1 Product Overview
The SENtral

M&M

Motion and Measurement Module is a castellated printed-circuit assembly
that makes it easy to quickly integrate a complete motion-sensor-fusion system into a mobile
device. A module incorporates the SENtral Motion Coprocessor, a magnetometer, an
accelerometer, and a gyroscope, with different SENtral M&M versions integrating different
sensor models. The SENtral Motion Coprocessor manages and uses data from the three sensors to
provide reliable motion tracking and an accurate compass heading, while consuming about 1% of
the power of a comparable ARM-based sensor fusion microprocessor. SENtral outputs Euler
angles (aka heading, pitch, and roll), quaternions, and sensor data. Quaternions uniquely define
orientation and, unlike Euler angles, do not experience a singularity (i.e. gimbal lock) when
pointing straight up. They easily can be converted to Euler angles, the rotation vector, and the
rotation matrix (aka DCM), as discussed in Appendix I.
1.1 SENtral Features and Benefits
At the heart of the SENtral M&M module is PNI’s revolutionary SENtral Motion
Coprocessor. Listed below are some of the features and benefits of this device.

Low power consumption. Offloads sensor processing from the less efficient host
CPU, consuming <1% of the power of a Cortex M0 running a comparable sensor
fusion algorithm. Provides the ability to tailor the tradeoff between power
consumption and motion-tracking performance.

Industry-leading heading accuracy. Unparalleled heading accuracy for consumer
electronics applications.

Continuous hard and soft-iron auto-calibration. Unlike other motion-tracking
products, SENtral calibrates for both hard-iron and soft-iron magnetic distortion.
Specifically, soft-iron distortion is quite difficult to correct, and can contribute up to
90° of error. It can be caused by materials widely used in mobile and consumer
electronic devices, such as EMI shielding tape and other shielding. Additionally,
since a host system’s magnetic signature can change over time and temperature,
SENtral’s continuous auto-calibration ensures accuracy over time.

Magnetic anomaly compensation. With SENtral, heading and motion tracking is
unaffected by short-term magnetic anomalies, such as rebar in buildings, desks,
speakers etc., that can easily throw off the accuracy. SENtral establishes if a transient
magnetic anomaly is present and compensates for this.

Sensor flexibility. SENtral works with most common consumer electronics motion
sensors, so designers can choose the sensors most appropriate for their systems.