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Xpari
I was wondering if anyone will be able to advise on which off-the-shelf ...
Edwuardo
ON the "Wiring up neuromorphic electronics" column, p27, the red text under the ...
Six-axis sensor fuses accelerometer with magnetometer
R Colin Johnson
6/18/2012 7:01 AM EDT
PORTLAND, 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.
Click on image to enlarge.
"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.
Click on image to enlarge.
Accelerometer and magnetometer data (left) is fused by embedded digital signal processor (DSP) functions (bottom) which conserves power in periods of inactivity.
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R_Colin_Johnson
6/18/2012 6:00 PM EDT
Bosch and Invensense already had six-axis e-compass combo chips, but Freescale claims to have an edge with its in-package DSP functions for sensor fusion. Freescale also swears by its magnetometer which uses the tunnel magnetoresistance (TMR) effect, which is CMOS friendly and being developed for MRAM too (spun-off as Everspin in 2008), has built-in tamper resistance capabilities plus a FIFO stores the last 32 samples so the applicaiton processor can catch up on readings it might have missed.
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goafrit
6/18/2012 8:51 PM EDT
Is anyone better than ST in this sector? I think they dominate the MEMS world by light years. Check their revenue. Freescale is largely also-ran.
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ewertz2
6/18/2012 10:21 PM EDT
You're right -- we should eliminate or ignore competition. That would simplify component selection greatly.
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Battar
6/19/2012 2:04 AM EDT
ST might be leading with accelerometers but they don't have a magnetometer in their portfolio. Honeywell sensing were pioneers in the field of e-compasses followed by Philips/NXP with KMZ series about a decade ago. Now Freescale and Honeywell seem to be the only players in the field.
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bkinsella
6/21/2012 12:42 PM EDT
ST didn't have a magnetometer until recently. The LSM333D (announced in March) is a combo accelerometer, gyro, and magnetometer. I believe they worked with Honeywell on the magnetometer part.
Also for magnetometers, don't forget AKM (Asahi Kasei Microdevices).
Freescale still don't have a gyroscope, which is a pity.
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docdivakar
6/24/2012 6:06 PM EDT
Freescale is on a catchup exercise here. Bosch and ST (and now InvenSense) have a bigger share of the market. The differentiations described in the comment above may help Freescale change some of that dynamic.
MP Divakar
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docdivakar
6/24/2012 5:56 PM EDT
@R_Colin_Johnson: I think the differences you point out between Freescale and others (in 6-axis combo MEMS chips) are easy to catchup except for the TMR effect. Differentiations can also come from intelligent application of 3D IC packaging technologies which has potential to further reduce real estate requirements.
MP Divakar
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Edwuardo
7/4/2012 1:03 PM EDT
ON the "Wiring up neuromorphic electronics" column, p27, the red text under the brain image has NEUROMOPHIC instead of neuromorphic......Ed
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Xpari
1/7/2013 10:55 PM EST
I was wondering if anyone will be able to advise on which off-the-shelf magnetometer will be most sensitive.
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