Accelerometer in next hardware revision?
Rene Mayrhofer
rene at mayrhofer.eu.org
Sun Apr 22 23:39:34 CEST 2007
Hi all,
Let me start my first post by saying thanks for initiating an open source
mobile phone platform!
My motivation for contributing stems from the background of ubiquitous
computing and the possibility to use mobile phones for research in this area.
Having an openmoko phone will be a huge benefit to research projects, and I
am looking forward to laying hands on the first hardware version to support
WLAN.
I would like to add to the existing wishlist item "Accelerometer" at
http://wiki.openmoko.org/wiki/Wish_List_-_Hardware that there is probably
many uses for it, e.g.:
- Detecting when the phone is being moved to the ear (this gesture is
detectable) and reducing audio output to a certain maximum as a safety
feature
- Switching on the LCD backlight based on gestures (like tilting it briefly)
- Gesture-based navigation in menus
- Switching display orientation (like the iPhone does it)
- A step counter (see Nokie 5500) and other sports uses
- Detecting motion in general and specific actions in particular (see e.g.
http://architecture.mit.edu/house_n/documents/Bao03.pdf or
http://www-static.cc.gatech.edu/~thad/p/031_20_Activity/pervasive04-lukowicz.pdf
about combining accelerometers with microphones to improve recognition
accuracy)
- or even secure pairing e.g. with a Bluetooth headset or other phones (sorry
for the shameless plug here, but details can be found at
http://www.mayrhofer.eu.org/downloads/publications/Pervasive2007-Shake-Well-Before-Use.pdf)
- and possibly many more...
Based on my own practical experience, 3D accelerometers are small, cheap, and
power-efficient enough to integrate into almost any mobile device. We are
currently using AMD ADXL330 accelerometers, which consume less than 200µA
(see http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf). If there
is no ADC on board to sample it, then other accelerometers with SPI output
could be used (e.g. the STM LIS3LV02DL with details at
http://www.st.com/stonline/products/literature/ds/12094/lis3lv02dl.pdf).
These of course consume more power, e.g. the STM up to 80mA.
If there is some interest in adding accelerometers, I would be happy to
provide more details and/or try to get more colleagues with various special
expertise involved.
PS: A laser pointer diode would also be very nice, with the same motivations
(small, cheap, and power-efficient) and again some applicability for secure
pairing (again, sorry for the plug:
http://www.mayrhofer.eu.org/downloads/publications/WAIS2007-Laser-Authentication.pdf).
with best regards,
Rene
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