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Sensors on Google Glass

Recently Google has shared the Linux Kernel source for the firmware running on the Google Glass. Having grown tired of watching online reviews about the monotonous "Glass this, glass that" voice commands, i was curious about the support for other forms of input. (read gestures). A quick peek into the innards of the kernel source revealed quite a lot...

FACT1. Google Glass runs on Texas Instruments OMAP4430.

Nothing revolutionary. A major win for TI (FWIW), considering that it has nonchalantly quit the mobile-SoC market citing a low RoI. This was already known as some guy who actually had the Google Glass, ran adb and found out.

FACT2. Google Glass has a built-in Accel, Gyro & Compass. 

Invensense MPU6050 = 3axis gyro + 3 axis accel.
Asahi Kasei AKM8975 = 3axis geomagnetic sensor(compass).
Combining facts 1 and 2 we can see that the device spec for SoC and sensors perfectly matches the popular Samsung Galaxy S2 (variant I9100G).

Rather than having independent ICs for both, the Google Glass uses MPU9150. Invensense MPU9150 is a single SiP which contains MPU6050 and AK8975 ICs within. This is fully hardware-compatible with existing MPU6050 board designs with the additional benefit of... (as Invensense quotes on its website) "...providing a simple upgrade path and making it easy to fit on space constrained boards." Perfect for Google Glass.
Refer: arch/arm/mach-omap2/board-notle.c line:1710

FACT3. Google Glass has a "glasshub"

I stumbled upon this by accident as i was searching for the sensor drivers. The glasshub appears to be a external micro-controller that communicates with OMAP4430 over I2C. This is the hardware that supports the "wink" command. Strangely enough, it supports upto 20winks! Looks like someone didn't learn their lesson with triple and quadruple mouse-clicks designs. On the other hand, this will be most essential when someone attempts to write a Google Glass app to detect seizures. Forward thinking as always, Google.

The glasshub also reports IR data and proximity (not sure about the underlying hardware though).


FACT4. Google Glass has a "Proximity" sensor.

Not to be confused with the "glasshub" there is another independent module, the LiteON LTR-506ALS. A very good sign, this IC is extremely customisable when it comes thresholds/IR-pulse-freq/pulse-count/poll-rate. Maybe, just maybe, we could hack the whole setup into a rudimentary IR remote. While being used primarily for ambient light sensing, it also supports proximity sensing. This means that we can have the Google Glass detecting our finger/hand swipes in front of our face. Quite the most exciting tech of the lot as it will provide the illusion of being able to actually handle the projected images.
Refer: arch/arm/mach-omap2/board-notle.c line:1727

Overall quite a good amount of
"sensory" tech inside for me to play with.
Me so excited. ;-) ;-) wink wink
Hey Google, Can i haz a Google Glass?