I have to admit to a sidebar problem in setting the thing up. I was ready to call for support when I couldn't get the two-button pairing action between the pieces to take. But then I discovered a thin, clear wrapper left on the AAA battery that powers the mousing device. Call it poor design (possibly) or user inattention (probably), but after that little problem was out of the way, it worked like a snap.
1Gbyte NAND memory
Gyration's $150 GO PRO Gyrotransport includes a free-space mouse as well as 1Gbyte of "playing around" storage within the separate USB transceiver dongle on the host PC.
The small USB transceiver on the PC side communicates to the mouse on a 2.4GHz link while hosting a gigabyte of NAND flash drive memory. In the unit analyzed, an MT29F8G08FAB 8Gbit (1Gbyte) NAND package from Micron Technology stacks four 256Mbyte SLC NAND chips in a TSOP to add a bonus to an already handy gadget. To make the memory usable as a flash drive, a Cypress Semiconductor CY7C68033 USB NAND flash controller handles both the USB and memory interfaces.
Joining the controller and memory is Cypress' CYWUSB6953, which creates half of the 2.4GHz wireless link needed to communicate with the airborne mousing device.
The mouse is powered by a Texas Instruments' MSP430F1232 mixed-signal MCU that has 8Kbyte plus 256byte of flash memory and 256byte of RAM.
Along with a TI boost DC/DC converter, the mouse contains the other half of the 2.4GHz wireless link in the Cypress CYWUSB6934 2.4GHz direct-sequence spread-spectrum radio SoC.
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Gyration's GO PRO Gyrotransport includes a free-space mouse as well as 1Gbyte of storage within the separate USB transceiver dongle on the host PC. (Click to view teardown.) |
Gyroscope inside
Although the Cypress WUSB part is an impressive item from the chip world, an equally intriguing part in the mouse is the MG1104 gyroscope module from Gyration. Gyration is owned by Movea, a funded spinout of Thomson of France, which still holds a minority stake.
The MG1104 was a surprisingly large and different sensor from what I expected to find in this era of silicon-MEMS accelerometers. The large-sugar-cube-sized module (about 14mm to a side) hosts semiconductor content, but only in a supporting role to the gyro sensor itself. The gyro's operation is based on some common physics in the form of the Coriolis effect.
I reluctantly use the "common," because I was slow to figure out how the physical gyro structure uses the principle. The critical aspect seems to be the Coriolis effect's ability to deliver horizontal and vertical acceleration from the velocity of the rotation and oscillation of the gyro plate when it is moved.
The transducer is an etched metal plate that forms an intricate web of fingers from a driven center point. At first glance, it resembles the old inserts used with 45rpm vinyl albums to allow them to be played on standard LP spindles. The plate is coupled to a driver coil that sets up a fundamental oscillation, and freestanding spokes in the plate seem to be the points of monitoring for a second, more-complex set of oscillation modes. A poor showing in freshman physics isn't helping me here, but the best explanation I can see is that the secondary oscillation modes in the spokes are affected when the metal plate's primary vibration experiences the acceleration of motion caused by mousing.
That's probably off as an accounting of how things work (and I encourage feedback to set me straight here), but the mechanical structure is fundamentally a source of dual-axis acceleration vectors when married to some signal processing. In that vein, a custom IC designed by Cadence for Gyration handles what must be a mix of op amps and A/D converters in the GYRC10433. The Cadence part reads the pickups to get acceleration data and converts it to a serial digital format readable from the module, for motion control purposes. A 256byte E²PROM stores calibration constants for the module, probably to compensate for any manufacturing variables.
Swift operation
In a final, clever step, the four signal/power connections for the gyro module are delivered over a set of vibration-isolating coiled wires that suspend the gyro apparatus, eliminating drift and externally induced pointing errors.
Although the product targets PowerPoint presenters, the notion of gesture-based control extends into many other possible domains, among them the world of PC-based TV remotes. In fact, Gyration will be happy to have you spend about $100 on its GYR3101CA WindowsMedia-compatible Universal Remote, a gadget that takes the basic Gyrotransport technology in a decidedly more consumer- oriented direction.
It's noteworthy that the raw silicon area dedicated to the core free-space mousing functions of this product is dwarfed by the nearly 6cm x 6cm area needed for the 1Gbyte of NAND memory. Although the storage capability of the Gyration product is intended to be an attractive secondary add-on function, the memory silicon real estate takes the podium by a wide margin.
It just goes to show that the big story in a product often comes from relatively small chips—and, as in the case of the gyro module, from something largely divorced from the world of silicon.
- David Carey
President, Portelligent
Keywords: gyroscope sensor gyro mouse NAND flash
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