Re: digital compass modules
Hi! A compass module would be very nice with many applications! I have no hardware related experince. Is it possible to integrate a chip like this into the phone? How would you do that? Jeff Andros wrote: sparkfun has a few, this one jumped out at me, but check out the rest http://www.sparkfun.com/commerce/product_info.php?products_id=7892 On Jan 22, 2008 8:02 PM, Robin Paulson [EMAIL PROTECTED] wrote: i've got a project in mind for when my neo freerunner arrives, that needs a digital compass. only a simple thing, probably 3 degree accuracy would be enough. so, can anyone recommend a suitable module? something less than $50? ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Am Mi 23. Januar 2008 schrieb Schmidt András: Hi! A compass module would be very nice with many applications! I have no hardware related experince. Is it possible to integrate a chip like this into the phone? How would you do that? True drop-in solution Simple I2C interface 2.7 to 5.2V supply range Supply current : 1mA @ 3V I2C is a bus, what means you should be able to simply tap the 2 wires of the existing I2C and connect to the chip(pin 7, 10). Another 2 wires for power (pin 5, 14) - 1 mA is pretty low consumption - and some birds food (Ca, Cb) and a drop of cyanide glue to stick the chip somewhere well away from magnetic interference (metal and high electric current). That's it. Some driver to read out the chip for the ones who like it the pretty way.. ;-) ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
On 23/01/2008, Schmidt András [EMAIL PROTECTED] wrote: Hi! A compass module would be very nice with many applications! I have no hardware related experince. Is it possible to integrate a chip like this into the phone? How would you do that? from the data sheet, this appears to connect via I2C, which the neo can interface with: http://wiki.openmoko.org/wiki/I2C ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
joerg schrieb: Am Mi 23. Januar 2008 schrieb Schmidt András: Hi! A compass module would be very nice with many applications! I have no hardware related experince. Is it possible to integrate a chip like this into the phone? How would you do that? True drop-in solution Simple I2C interface 2.7 to 5.2V supply range Supply current : 1mA @ 3V I2C is a bus, what means you should be able to simply tap the 2 wires of the existing I2C and connect to the chip(pin 7, 10). Another 2 wires for power (pin 5, 14) - 1 mA is pretty low consumption - and some birds food (Ca, Cb) and a drop of cyanide glue to stick the chip somewhere well away from magnetic interference (metal and high electric current). That's it. Some driver to read out the chip for the ones who like it the pretty way.. ;-) I doubt that such a device would work in the phone, sorry. The GTA01 contains three loadspeakers with magnets, AFAIK GTA02 will still contain at least two. Then there is massive EM radiation from the GSM antenna which will interfere and finally there is the Bluetooth module also emitting EM when used. Earth's magnetic field is very weak so almost *any* EM radiation near to the measuring device (the chip) will interfere. Cheers nils faerber -- kernel concepts GbRTel: +49-271-771091-12 Sieghuetter Hauptweg 48Fax: +49-271-771091-19 D-57072 Siegen Mob: +49-176-21024535 -- ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Hi! I was thinking about the same problem. But once I have seen a working compass in a phone already (we have crossed thick woods following the compass :-) - it was a friend's phone, I think a Nokia). So it is not impossible to integrate into a phone. In my opinion: 1. The GSM is not radiating constantly when it is idle. 2. You can switch the bluetooth off when wandering in woods. 3. The loudspeaker's magnet must be avoided by placing the chip far from that Perhaps the phone with compass was specially designed so that it interferes the least possible with Earth's magnet sensor. But perhaps it could be possible to integrate into the freerunner. I think it will worth experimenting :-). Conclusion is always the same: I am getting more impatient waiting for my phone :-) Nils Faerber wrote: I doubt that such a device would work in the phone, sorry. The GTA01 contains three loadspeakers with magnets, AFAIK GTA02 will still contain at least two. Then there is massive EM radiation from the GSM antenna which will interfere and finally there is the Bluetooth module also emitting EM when used. Earth's magnetic field is very weak so almost *any* EM radiation near to the measuring device (the chip) will interfere. Cheers nils faerber ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Am Mi 23. Januar 2008 schrieb Nils Faerber: I doubt that such a device would work in the phone, sorry. The GTA01 contains three loadspeakers with magnets, AFAIK GTA02 will still contain at least two. Then there is massive EM radiation from the GSM antenna which will interfere and finally there is the Bluetooth module also emitting EM when used. Earth's magnetic field is very weak so almost *any* EM radiation near to the measuring device (the chip) will interfere. GSM with no call established is intermittant if any RF (else the battery would drain quite quickly, in fact there's a burst every ~60min or so for T321 refresh). BT may be switched off. The compass device may read out with 20Hz so you may allways get some good readings in between, even while established GSM connection. Furthermode RF is no static magnetic field, it shouldn't care at all. We are talking about DC here, not HF. For the speaker's magnets: they clearly are a strong source of error, but the datasheet says the chip might calibrate to compensate for this IIRC. Anyway the chip should be positioned as far away from each such source of magnetic interference as possible. (for a first simple test, put a small old fashioned compass on top of the Neo and check it out. As long as you get any reproduceable orientation dependent steady reading, chances are good) What you never may compensate is current generated fluctuating magnetic fields when e.g. GSM module is pulling random 1A from battery and the + and - leads aren't parallel/twisted or *magnetic* shielded. So compass readout probably should be done in low power mode of the NEO - no backlight, no GSM transmission, no full speed CPU. jOERG ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Schmidt András wrote: Hi! A compass module would be very nice with many applications! I have no hardware related experince. Is it possible to integrate a chip like this into the phone? How would you do that? Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Tilman Baumann wrote: Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) 2. A software rendered compass (I have already seen one on a phone as I mentioned in a previous mail) Certainly these applications work best when the magnet sensor is fixed to the device itself :-). BT may work, but is an overkill. The I2C solution sugested by joerg and Robert Paulson seems to fit better. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
I'm not sure a magnetic sensor is useful when you have a GPS, because a GPS can give you a heading as soon as the measured velocity is not zero! However I think it's possible to calibrate a magnetic sensor so that it forgets its close magnetic environment and is only sensitive to the intented magnetic signals. The magnetic environment is stored as a fingerprint and is then substracted to the raw measurements to get a correct value. Sebastien ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Hello, Citeren Schmidt András [EMAIL PROTECTED]: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) A handheld GPS use the change in position measured by GPS to determinate the direction of movement and is able to turn the display in that direction. In fact, when the GPS is working like it should (IE very good with the planned chipset) this is the best way to calculate the heading. Most important: it's already there in the phone. Met vriendelijke groet, Luc Bos ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Le 13901ième jour après Epoch, Schmidt András écrivait: Tilman Baumann wrote: Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Sébastien Lorquet wrote: I'm not sure a magnetic sensor is useful when you have a GPS, because a GPS can give you a heading as soon as the measured velocity is not zero! It is true when you use it in a car when cruising with normal speeds. When you are using your GPS on foot (installed with a hiking map) your velocity's direction is not well defined enough and also when you stop for navigating you usually turn a different direction than you were walking. (I would use my device this way when hiking or geocaching - see http://www.geocaching.com/) Also sometimes I get fed up with the GPS and navigate using old fashioned paper maps. A compass always comes handy ;-). ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
François TOURDE wrote: Le 13901ième jour après Epoch, Schmidt András écrivait: Tilman Baumann wrote: Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. Right! That was an other possible solution I was thinking about. Though I think that algorithm should be very carefully implemented (a very sensitive regulator filter) not to accumulate the measurment error of the accelerometer, and corrigate with the GPS signal when possible. I am not even sure it is possible. Precision would get worse when you are moving slow and shake the device (the case on foot). The regulator code would also consume much energy. Direct measurment of direction seems to be much better for me. These are only speculations with little information and no experience with such devices (accelerometer and magnetic sensor in fact). ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Am 23.01.2008 um 14:37 schrieb Sébastien Lorquet: I'm not sure a magnetic sensor is useful when you have a GPS, because a GPS can give you a heading as soon as the measured velocity is not zero! It is exactly useful for this reason: if you are not travelling by car but as a pedestrian, the GPS direction calculation is quite imprecise. And if you simply rotate the device to rotate the map, you have velocity zero. However I think it's possible to calibrate a magnetic sensor so that it forgets its close magnetic environment and is only sensitive to the intented magnetic signals. The magnetic environment is stored as a fingerprint and is then substracted to the raw measurements to get a correct value. Look how the Garmin eTrex summit https://buy.garmin.com/shop/ shop.do?pID=143 is doing: 1. it has an additional magnetic sensor 2. you have to calibrate it once you replace the batteries (metallic/ magnetic!) 3. calibration is done by rotating the device once by 360 degrees in approx. 2-3 seconds Am 23.01.2008 um 14:25 schrieb Schmidt András: I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) 2. A software rendered compass (I have already seen one on a phone as I mentioned in a previous mail) 4. the waypoint tracking map is rotated accoring to the orientation of your device 5. a compass can be shown graphically So, these ideas are indeed reasonable and already implemented in a commercial GPS device but not in mobile phones. Nikolaus Schaller ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
On Wednesday 23 January 2008, Schmidt András wrote: François TOURDE wrote: Right! That was an other possible solution I was thinking about. Though I think that algorithm should be very carefully implemented (a very sensitive regulator filter) not to accumulate the measurment error of the accelerometer, and corrigate with the GPS signal when possible. I am not even sure it is possible. Precision would get worse when you are moving slow and shake the device (the case on foot). The regulator code would also consume much energy. Direct measurment of direction seems to be much better for me. These are only speculations with little information and no experience with such devices (accelerometer and magnetic sensor in fact). GPS combined with INS? I think the accelerometers aren't accurate enough for INS ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Frans Grotepass wrote: On Wednesday 23 January 2008, Schmidt András wrote: I am not even sure it is possible. GPS combined with INS? I think the accelerometers aren't accurate enough for INS I have the same opinion though I don't know what INS resolves to :-). Could you tell what INS stands for? Thanks! ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
On Wednesday 23 January 2008, ground control picked up the following transmission from [EMAIL PROTECTED]: Citeren Schmidt András [EMAIL PROTECTED]: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) A handheld GPS use the change in position measured by GPS to determinate the direction of movement and is able to turn the display in that direction. In fact, when the GPS is working like it should (IE very good with the planned chipset) this is the best way to calculate the heading. Most important: it's already there in the phone. Use case: I'm hiking in the mountains, heading 0 degrees (due north) at 5 km/h. I stop because there's something interesting off to the left, and I want to get its exact bearing (let's assume that's something like 283 degrees). So I rotate the GPS so up points at the object of interest. Results: Handheld with internal compass (for example, many Garmin units) can give me correct bearing to the object. Neo thinks bearing to the object is 0 degrees, since I'm not moving and you can't compute rotation about axis with GPS signal only. Failure mode: Stationary GPS is more subject to false readings due to reflection than moving GPS. Due to reflections, Neo might think I'm moving in some random direction, and give a bogus heading that appears reliable. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Am Mi 23. Januar 2008 schrieb Sébastien Lorquet: I'm not sure a magnetic sensor is useful when you have a GPS, because a GPS can give you a heading as soon as the measured velocity is not zero! You get heading of *velocity vector*, NOT heading of *device*! So for Andras' intended use, this is worth nothing. It works only for objects like a car that supposedly are not able to move in a direction different to straight forward. I even guess if you drive backwards with your car, the map on those navi-units will rotate top down. j ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
François TOURDE wrote: Le 13901ième jour après Epoch, Schmidt András écrivait: Tilman Baumann wrote: Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. Gyroscopes is what you look for. ;) Accelerameters don't see rotational movings. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Am Mi 23. Januar 2008 schrieb Tilman Baumann: François TOURDE wrote: Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. As stated in prev posting, GPS _can_not_ deliver bearing of device at all. Imagine having the GTA in your pocket while moving - there's not the faintest relation between movement vector as seen by GPS and bearing of GTA. Gyroscopes is what you look for. ;) Accelerameters don't see rotational movings. Though gyro won't help here at all, i think TWO 3D-accelerometers placed some distance from each other in a system make a nice gyro with the aid of some mathematics in driver. IIRC there was mentioned more than one acc-meter for the GTA. I thought that's exactly for this purpose. jOERG ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
Le 13901ième jour après Epoch, Tilman Baumann écrivait: François TOURDE wrote: Le 13901ième jour après Epoch, Schmidt András écrivait: Tilman Baumann wrote: Bluetooth would be nice. You would need no hardware hacks on the phone itself. Should be pretty easy to hack a bluetooth-serial converter (like BlueSMiRF from sparkfun) to the sensor. Maybe with a little microcontroller glue in between. Bluetooth is very simple to code and simple to handle. I was thinking about two possible applications: 1. The map of a GPS map viewer application turns when you turn the machine so it is always aligned with the environment (this feature is included on some GPS tools.) Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. Gyroscopes is what you look for. ;) Yes, but it's not (yet?) included in the phone :) ... But accels are. Accelerameters don't see rotational movings. Except if this is 3D accels. If we omit the case of a rotation around the accels center (and we can because there is 2 accels), a rotation can be measured using this kind of devices. I imagine it's not so easy, but I think it's possible... with my poor knowledges in physics :) ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
You cannot calculate North (or any Heading) from Accelerometer data. You need a 3D Gyroscope (or 3 Gyros on 3 orthogonal axis). With this you can detect the orientation of the gyro relative to earth's rotational axis, and calculate gyroscope north from that. This is the same as true north if the device does not move. If the device moves, you need to compensate for the motion, this can be done using latitude and speed over ground from GPS. You can, however, calculate north from the data of two GPS antennas about 1 meter apart, if you throw the *raw* data at a smart enough DSP. But this has to be raw data, not filtered NMEA output. There are devices using either concept available if you search the web, but this is mainly high-end equipment worth 50 Neos or more. Mostly used in Mil applications. I once found a small device with GPS, Gyro and Accelerometer inside a box the size of the Neo, for use in robotics or remote controlled vehicels. But even this would sell for the price of 3-4 Neos. The Gyroscopes need to be quite exact to get a reasonable north heading, with toy Gyros you can probably better estimate north from azimuth of the sun. I hope this explains a little, just some thoughts I wanted to share, because I looked into this stuff some time ago. Fair winds, Eddie Denis wrote: I think the accelerometers don't provide enough accuracy. 2008/1/23, joerg [EMAIL PROTECTED]: Am Mi 23. Januar 2008 schrieb Tilman Baumann: François TOURDE wrote: Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. As stated in prev posting, GPS _can_not_ deliver bearing of device at all. Imagine having the GTA in your pocket while moving - there's not the faintest relation between movement vector as seen by GPS and bearing of GTA. Gyroscopes is what you look for. ;) Accelerameters don't see rotational movings. Though gyro won't help here at all, i think TWO 3D-accelerometers placed some distance from each other in a system make a nice gyro with the aid of some mathematics in driver. IIRC there was mentioned more than one acc-meter for the GTA. I thought that's exactly for this purpose. jOERG ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community -- ___brainaid_ Eddie C. Dost Rue de la Chapelle 51 phone +32 87 788817 B-4850 Moresnetfax +32 87 788818 [EMAIL PROTECTED] Belgiumcell +49 172 9312808 ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
On Wednesday 23 January 2008, Denis wrote: I think the accelerometers don't provide enough accuracy. For INS you need both 3d axial as rotational accelerometers. For a quick check how it works, check out the wikipedia. One of the first big uses was Nautilus under the Polar ice cap. The combo could work, if you have enough info, but two (or three) axial meters can not do rotation. You could do it with 2 axial meters on each plane. The difference between the two is the moment on the device. So with 6 accelerometers you might give it a shot. If they are accurate enough, you might be able to remove the GPS jitter. 2008/1/23, joerg [EMAIL PROTECTED]: Am Mi 23. Januar 2008 schrieb Tilman Baumann: François TOURDE wrote: Maybe the 3D accels can do that. And the GPS can be used as a bearing indicator, when you move. No magnetic device needed in this case. As stated in prev posting, GPS _can_not_ deliver bearing of device at all. Imagine having the GTA in your pocket while moving - there's not the faintest relation between movement vector as seen by GPS and bearing of GTA. Gyroscopes is what you look for. ;) Accelerameters don't see rotational movings. Though gyro won't help here at all, i think TWO 3D-accelerometers placed some distance from each other in a system make a nice gyro with the aid of some mathematics in driver. IIRC there was mentioned more than one acc-meter for the GTA. I thought that's exactly for this purpose. jOERG ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
The Nokia 5140 has a compass that works in the conventional method, by reading the Earth's magnetic field vectors. http://europe.nokia.com/A4144100 See the user guides, which are made with Flash... :o Here is a page in Finnish with more information about the compass .. sorry, couldn't find this in English. http://www.nokia.fi/A4312238 A quick translation: *Nokia 5140i -electronic compass technologies: * - 2D sensor with a GUI - detects the horizontal x and y vectors of the Earth's magnetic field - tilt indicator (air bubble) *Compass function:* - Electronics: - Driver control interface detector (?) = magnetometer - Test circuit = continuous magnetic field generator - Software: - Compass with a needle + angle in degrees - Direction on-screen arrow - Direction may be set on a landmark and followed, and the offset from North may be entered - 1 degree precision - Mechanics - tilt detection 2008/1/23, Schmidt András [EMAIL PROTECTED]: Hi! I was thinking about the same problem. But once I have seen a working compass in a phone already (we have crossed thick woods following the compass :-) - it was a friend's phone, I think a Nokia). So it is not impossible to integrate into a phone. ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
digital compass modules
i've got a project in mind for when my neo freerunner arrives, that needs a digital compass. only a simple thing, probably 3 degree accuracy would be enough. so, can anyone recommend a suitable module? something less than $50? ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
Re: digital compass modules
sparkfun has a few, this one jumped out at me, but check out the rest http://www.sparkfun.com/commerce/product_info.php?products_id=7892 On Jan 22, 2008 8:02 PM, Robin Paulson [EMAIL PROTECTED] wrote: i've got a project in mind for when my neo freerunner arrives, that needs a digital compass. only a simple thing, probably 3 degree accuracy would be enough. so, can anyone recommend a suitable module? something less than $50? ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community -- Jeff O|||O ___ OpenMoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community
