From EETimes: The new Android 4.4 KitKat operating system announced by Google yesterday aims to save battery life by mandating that real-time location tracking and contextual awareness functions run in the background while the application processor is off. Usually, that means using a sensor hub to offload the application processor, but in anticipation of KitKat, InvenSense has built those functions into the on-chip digital motion processor (DMP) of its recently announced six-axis combo accelerometer/gyroscope.
"Google's new Android KitKat requires that many new sensor functions to run either in a sensor hub, which has the disadvantage of added cost, or in the sensor itself, which is the case with our new six-axis MPU-6515, which has its own digital motion processor." Ali Foughi, vice president of marketing and business development at InvenSense, told us.
The MPU-6515 combines a three-axis accelerometer with a three-axis gyroscope in the same package with an enhanced version of its DMP that has been specifically geared to handle the functions Android KitKat mandates running while the application processor is off. "Google with KitKat wants the sensor to be on more of the time, to provide real-time location and context awareness features, which would run the battery down without a sensor hub or, alternatively, using our chip."
In particular, during periods of inactivity, Android KitKat aims to shut down the application processor and then wait for a "significant-motion" interrupt with fewer false triggers before switching the application processor back on. KitKat also requires that pedometer functions, including step detect and step count, run in the background. For accurate inertial location tracking while the application processor is off, KitKat requires that six-axis rotation vectors, which involve fusing the outputs of accelerometer and gyroscope sensors, be taken periodically between interrupts. And a new batch mode allows for buffering these events between significant-motion interrupts.
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