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Freescale says low-power MEMS smarter, too

PORTLAND, Ore.—The user experience for mobile devices will soon get richer according to Freescale Semiconductor Inc., which announced its new generation of three-axis micro-electro-mechanical system (MEMS) accelerometers Monday (Feb. 15) at the Mobile World Congress.
Freescale (Austin, Texas) claims the devices set a record for low-power consumption and provide smarter built-in gesture recognition algorithms.

“Developers of mobile phones and other consumer devices using our new, smarter accelerometer can now incorporate enhanced functionality to improve the end user's experience, while extending battery life too,” said Demetre Kondylis, vice president and general manager of Freescale's Sensor & Actuator Solutions division. “Only 3 percent of mobile phones used an accelerometer in 2007, but we expect that number to jump to 33 percent in 2010 thanks to advances in MEMS technology and consumer demand for enhanced user interfaces.”

The stakes are high, since the MEMS market is expected to reach $8.3 billion by 2012, up from $5.6 billion in 2006, according to market research firm iSuppli Corp. MEMS accelerometers in particular are used for a variety of smart functions, from power management to extend battery life to shutting down if you drop it to gesture recognition in the user-interfaces built by original equipment manufacturers. OEMs are expected to use Freescale's new three-axis accelerometer in portable consumer devices including mobile phones, remote controls, smartbooks, eReaders, netbooks, laptop PCs, GPS navigators, handheld medical devices and for safety shutoff functions in power tools and small appliances, according to the company.

“Our new MMA8450Q three-axis accelerometer consumes less power than any other accelerometer of which we are aware,” said Michelle Kelsey, Freescale's marketing manager for inertial sensors. “Any mobile device choosing our accelerometer will extend its battery life considerably.”

The new accelerometer, which received Freescale's energy efficient solutions mark rating, features a low-power mode that reduces functionality for tasks that do not require it, such as merely switching from landscape to portrait mode, which can be performed while power consumption is as low as 27 microamps, Freescale said. In standby and shutdown modes the accelerometer consumes as little as 2 microamps, the company said.

The higher accuracy of its 12-bit digital output is coupled to refined on-chip algorithms that simplify the OEM's task of adding intelligence to enhance the user experience, according to Freescale. Built-in algorithms include tap detection, shake detection, jolt detection, free-fall detection, auto wake, auto sleep and orientation detection, the company said.

Anyone who has used orientation detection to switch from landscape to portrait mode on a device has experienced frustration when it switches too slowly when viewing photos, and too quickly otherwise. By adding parameters to its algorithm, Freescale claims to have made it possible for OEMs to avoiding these glitches and improve the user experience.

“We've made all our built-in algorithms smarter. For instance, in the case of orientation detection, we now have custom shift points you can set,” Kelsey said. “First-generation accelerometers have a set trip point of 45 degrees when switching from portrait to landscape modes. But now OEMs can set it to be more difficult or easier on the fly, so that if you are, say, dialing a number, it can be made more difficult to switch modes, but if you are looking at pictures, then it can be made easier to switch orientations.”

The MMA8450Q also has an internal first-in/first-out (FIFO) that holds 32-samples per axis in the memory buffer to offload the application processor which can be notified with an interrupt whenever the FIFO is close to overflowing, according to Freescale.

At the Mobile World Congress, Freescale is also showing its smartbook reference design to demonstrate the enhanced intelligence of the MMA8450Q three-axis accelerometer, as well as its application development kits for the MEMS chip, including PC boards and the Sensor Toolbox demonstration and evaluation software.

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