https://maemo.octonezd.me/api.php?action=feedcontributions&feedformat=atom&user=121.2.44.137 2026-04-22T01:56:14Z User contributions MediaWiki 1.45.1 https://maemo.octonezd.me/index.php?title=Digital_compass&diff=6225 2009-10-03T08:25:03Z

<p>121.2.44.137: </p> <hr /> <div>All information pertains to the N900.<br /> <br /> = Why a compass is needed =<br /> == Augmented Reality (AR) ==<br /> * GPS gives location of device; compass gives orientation<br /> * Allows pointing the device and getting information relevant to the pointed direction<br /> * E.g. Layar, Wikitude<br /> == Navigation ==<br /> * Car navigation<br /> * On-foot navigation<br /> ** Map rotation<br /> <br /> = Connection options =<br /> <br /> * Optical (use one of the cameras, plus image processing)<br /> ** Best to use user-facing camera, so the world-facing can be used for capturing the world image for AR<br /> * USB<br /> ** Unknown if USB host possible.<br /> ** Unknown if power is available from USB.<br /> * IRDA<br /> ** Seems unsupported at this point<br /> * Bluetooth<br /> ** Bluetooth data<br /> ** Bluetooth audio - sending analog signals via Bluetooth microphone for digital signal processing on the N900<br /> * FM radio<br /> ** Requires headphones be connected<br /> ** Signal processing of audio in software<br /> <br /> = Compass chips or sensors =<br /> * Honeywell HMC5843<br /> ** I2C interface<br /> ** Magnetometer requires vector math on client side for interpretation, see OpenMoko i2c compass project for more info<br /> * Dinsmore analog<br /> <br /> = Ready-built compass modules =<br /> * Ocean Server OS4000<br /> * Ocean Server OS5000<br /> ** USB and RS232 interface<br /> <br /> = Microcontrollers =<br /> <br /> = Converters =<br /> * I2C to RS232<br /> ** http://www.gedanken.demon.co.uk/rs232-converters/i2c.html<br /> ** http://www.i2cchip.com/<br /> * RS232 to Bluetooth<br /> ** Sparkfun BlueSmiRF Gold<br /> * I2C to USB<br /> ** http://www.harbaum.org/till/i2c_tiny_usb/<br /> * I2C to Bluetooth<br /> ** http://www.emv-electronics.com/de/intro/i2cbusadapter.htm (seems unavailable for purchase)<br /> <br /> = Designs =<br /> == Optical image processing of compass ==<br /> * Periscope-like mirror<br /> == Ready-made RS232 compass modules with RS232-Bluetooth conversion ==<br /> == Custom board designs ==<br /> <br /> = Alternatives to a digital compass =<br /> * Use GPS motion to determine direction<br /> ** Only useful for navigation, not AR<br /> ** Does not work if standing still<br /> * Use image processing for AR<br /> ** E.g. artoolkit<br /> ** Still you cannot get absolute orientation of device<br /> * Initialized orientation + delta orientations<br /> ** Maybe you can initialize the device to a known orientation (e.g. straight north), then use optical flow and/or accelerometer data to extrapolate subsequent orientations<br /> * Optical compass + manually dragging an on-screen compass to match<br /> ** Not automatic so some AR apps like games might not work<br /> ** But for navigation or rotating maps, it could work: just glance at the optical compass, then drag the map icon to match the orientation.</div>

121.2.44.137 https://maemo.octonezd.me/index.php?title=Digital_compass&diff=6226 2009-10-03T08:17:53Z

<p>121.2.44.137: Starting to gather the info from the DIY compass thread, not finished yet, please help!</p> <hr /> <div>All information pertains to the N900.<br /> <br /> = Connection options =<br /> <br /> * Optical (use one of the cameras, plus image processing)<br /> ** Best to use user-facing camera, so the world-facing can be used for capturing the world image for AR<br /> * USB<br /> ** Unknown if USB host possible.<br /> ** Unknown if power is available from USB.<br /> * IRDA<br /> ** Seems unsupported at this point<br /> * Bluetooth<br /> ** Bluetooth data<br /> ** Bluetooth audio - sending analog signals via Bluetooth microphone for digital signal processing on the N900<br /> * FM radio<br /> ** Requires headphones be connected<br /> ** Signal processing of audio in software<br /> <br /> = Compass chips or sensors =<br /> * Honeywell HMC5843<br /> ** I2C interface<br /> ** Magnetometer requires vector math on client side for interpretation, see OpenMoko i2c compass project for more info<br /> * Dinsmore analog<br /> <br /> = Ready-built compass modules =<br /> * Ocean Server OS4000<br /> * Ocean Server OS5000<br /> ** USB and RS232 interface<br /> <br /> = Microcontrollers =<br /> <br /> = Converters =<br /> * I2C to RS232<br /> ** http://www.gedanken.demon.co.uk/rs232-converters/i2c.html<br /> ** http://www.i2cchip.com/<br /> * RS232 to Bluetooth<br /> ** Sparkfun BlueSmiRF Gold<br /> * I2C to USB<br /> ** http://www.harbaum.org/till/i2c_tiny_usb/<br /> * I2C to Bluetooth<br /> ** http://www.emv-electronics.com/de/intro/i2cbusadapter.htm (seems unavailable for purchase)<br /> <br /> = Designs =<br /> == Optical image processing of compass ==<br /> * Periscope-like mirror<br /> == Ready-made RS232 compass modules with RS232-Bluetooth conversion ==<br /> == Custom board designs ==</div>

121.2.44.137