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InvenSense Introduces Motion Sensors for Wrist-Worn Devices with Automatic Activity Recognition (AAR™)

The new MPU-6555, available from Glyn High-Tech Distribution, is InvenSense’s first generation 6-axis (3-axis gyroscope + 3-axis accelerometer) activity detection device, working in conjunction with their Automatic Activity Recognition library (AAR™) in a 3x3x0.9mm (24-pin QFN) package.

Activity recognition is the identification of personal activities by analysing a user’s motion. It uses trained data from the user, then compresses the data into a decision tree format that can be used to identify when the activity occurs again in the future. Simply put, automatic activity recognition allows a wearable sensor device to track your activities without the user having to tell the device that he or she is switching from one activity to another (e.g. from jogging to biking to walking). The InvenSense low power sensor can detect run, walk, bike, no-motion, and sleep analysis on a wrist-worn wearable device.

This solution is ideal for Smart Watch, Smart Band, and Fitness Tracker applications that want to enable the next generation features for wearable products. The library uses data calculated on the on-chip DMP (Digital Motion Processor) to recognize new activities typically within 10 seconds and with 95% accuracy for true positives. The AAR™ library offers a high accuracy pedometer that benefits from the contextual awareness of knowing which activities will require steps and which will not as well as elevation tracking. The AAR™ library is optimized to recognize the users “persistent” activity useful in applications where you are trying to catalogue the user’s daily fitness level.  These devices will enable consumers to become more health conscious. Important questions such as how much time did I spend sitting, walking, exercising and sleeping? How does this match to the activity goals I’ve set for myself? While exercising, did I expend more calories on my 30 minute run or 10 minute bike ride will all be quantified.

The MPU-6555 also features a 512-byte FIFO that can lower the traffic on the serial bus interface, and reduce power consumption by allowing the system processor to burst read sensor data and then go into a low-power mode. With its dedicated I2C sensor bus, the MPU-6555 directly accepts inputs from external I2C devices. MPU-6555 is also designed to interface with multiple non-inertial digital sensors, such as pressure sensors, on its auxiliary I2 C port. The gyroscope has a programmable full-scale range of ±250, ±500, ±1000, and ±2000 degrees/sec and very low rate noise at 0.01 dps/√Hz. The accelerometer has a user-programmable accelerometer full-scale range of ±2g, ±4g, ±8g, and ±16g. Factory-calibrated initial sensitivity of both sensors reduces production-line calibration requirements.

Other industry-leading features include on-chip 16-bit ADCs, programmable digital filters, a precision clock with 1% drift from -40°C to 85°C, an embedded temperature sensor, and programmable interrupts. The device features I2C and SPI serial interfaces, a VDD operating range of 1.71 to 3.6V, and a separate digital IO supply, VDDIO from 1.71V to 3.6V.

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.

A 9-axis version of the motion sensor chip with AAR™ is also available for applications requiring digital compass.  The InvenSense MPU-9255 is a System in Package (SiP) that combines two chips: the MPU-6555, and the market leading 3-axis digital compass with an onboard Digital Motion Processor™ (DMP) capable of processing complex MotionFusion™ algorithms.

InvenSense also offers Sharkband 1.0 which is a wrist worn demo platform that highlights the feature set found in the InvenSense Automatic Activity Recognition (AAR) library. This band features the MPU-6555 but can also support the 9-axis MPU-9255 motion sensor. Sharkband offers a desirable form factor, excellent power management, and most importantly their proprietary Automatic Activity Recognition Library ™ designed specifically for health and fitness tracking applications. Not only does it greatly minimize your time-to-market by integrating all the key components (MCU, BLE, Motion sensors, Pressure sensor) of a wrist-worn wearable device but it also comes with the integrated embedded software that manages all these components efficiently to allow 5-6 days of battery life (55 mAHr battery) with “Always On” 24/7 Activity recognition using the AAR™ Library.

To order samples of InvenSense MPU-6555, please visit Glyn Store here

For more information about InvenSense MPU-6555, please contact Glyn High-Tech Distribution at