PORTLAND, Ore.—Freescale Semiconductor Inc.'s new Xtrinsic family of smart MEMS sensors combine a 32-bit ColdFire microcontroller with on-chip algorithms for all the common operations like tap, touch, tilt and orientation, thereby streamlining designs and offloading the application processor, the company said Tuesday (June 22).
"We are supplying a smart system-in-package that gives you both an inertial sensor along with the intelligent algorithms designers need to craft an application," said Bryce Osoinach, touch sensor systems and applications engineer at Freescale.
The system-in-package combines a ColdFire 32-bit microcontroller die alongside a three-axis MEMS accelerometer die. The same 3-by-3 millimeter package also contains on-chip power management and dual I2C/SPI connectivity buses—one for communicating with the host application processor, and the other for communicating with up to 12 other sensors needed in a design, such as MEMS gyroscopes, pressure sensors, magentometors, or touch sensors.
Besides off-loading the application processor in a design from reading out sensor data, the on-chip firmware that is supplied with every Xtrinsic sensor provides many of the common algorithms that would otherwise have to be executed by the application processor, as well as the sensor fusion operations needed to use multiple sensors. On-chip flash can also accommodate custom sensor fusion operations, such as to emulate Wii-like gaming controllers with MotionPlus. For instance, the on-chip accelerometer can be used together with an external MEMS gyroscope to achieve ultra-precise motion tracking for 3-D mice and MotionPlus fuctionality. A barometric pressure sensor can also be added for altitude along with a magnetometer, and sensor fusion algorithms can perform indoor navigation tasks.
Besides claiming the highest resolution output in the industry—14-bits—every member of Freescale's new Xtrinsic family of smart system-in-package sensors includes on-chip capacitive touch sensing and suite of software to manage most functions like buttons, sliders and rotary dials, according to Freescale.
On-chip power management includes configurable sample rate, auto-wake monitors and auto-sleep modes to powers down sensor when they are not in use. A smart first-in-first out allows samples from sensors to accumulate without having to wake the processor for each new reading, according to Freescale.
An Xtrinsic Touch Sensing Software Suite is available now as well as a Touch Sensing Software evaluation board from Freescale.
Sensor fusion is essential to harness the gyroscopes that will be included in nearly every smartphone in the future, starting with Apple's new iPhone 4. Freescale claims that using a "smart MEMS" chip, with an integrated microcontroller with built-in fusion algorithms in firmware, will enable future devices to be cost reduced. But you would think that using a cheaper dumb MEMS chip would enable an even lower price point for devices. As a working engineer, which side of this argument do you favor?
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