Six-axis sensor fuses accelerometer with magnetometerPORTLAND, Ore.—Digital e-compasses typically fuse data from a magentometer and accelerometer in order to accurately determine heading and orientation, enabling location-based services for navigation, gaming and augmented reality (AR). By housing its magnetometer and accelerometer in the same package with a digital signal processor (DSP), enabling higher accuracy sensor fusion, Freescale Semiconductor Inc. hopes to capture a bigger share of the $1.5 billion market for e-compasses forecast by ABI Research by 2016.
"Pedestrian navigation applications on mobile phones was really driving the higher accuracy for this device," said Michelle Kelsey, a product line manager at Freescale. "There is also a lot of interest in a combo device with lower power consumption and with the embedded functionality we have provided for gaming an other applications that want to offer the consumer quicker and more realistic response from an e-compass."
The built-in sensor fusion for the 16-bit magnetometer and 14-bit accelerometer is performed in real time by the in-package DSP hardware to provide faster more accurate headings and orientation readings than with separate devices fused with an application processor, according to Kelsey.
The tiny 3-by-3-by-1.2 millimeter package resolves heading within 0.1 degrees and can sense plus or minus 1,200 microTeslas with non-critical placement on printed circuit boards by virtue of compensation algorithms for permanent magnets, speakers and vibrator motors in mobile phones. The FXOS8700CQ device is compatible with Freescale's existing sensor fusion software libraries as well as its recently announced 12-axis sensor fusion reference platform.
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Accelerometer and magnetometer data (left) is fused by embedded digital signal processor (DSP) functions (bottom) which conserves power in periods of inactivity.