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muwimax is offline muwimax
2009-10-27 , 23:19
Posts: 16 | Thanked: 0 times | Joined on Sep 2009 @ Turkey
#71
how did I missed that =D thanks
 
wickeddeus is offline wickeddeus
2009-10-28 , 18:38
Posts: 5 | Thanked: 0 times | Joined on Oct 2009
#72
I don't know if this has been suggested yet but why not use the same digital compass that is currently in the Iphone 3GS (and all of the Android phones, I believe)? The unit is Asahi Kasei's AK8973S. From the specs I was able to pull from the internet, the chip-size packaging is 2.5 x 2.5 x 0.5 mm. I don't know if it is technically possible but someone might be able to fit it inside a microSD body (microSD being 15 mm × 11 mm × 1 mm). It might even be possible to make the card do double duty as a digital compass plus memory storage.
 
Otaku is offline Otaku
2009-10-31 , 04:01
Posts: 71 | Thanked: 34 times | Joined on Sep 2009
#73
Originally Posted by qole View Post
Rather than a periscope, what about some kind of lens that could be placed between the camera and the compass that would allow the camera to focus on a tiny ball compass pressed right against the camera? That would certainly be more compact and lit would allow more light to shine on the compass...
Interesting idea. Do you know any cheap lenses that could be used for this purpose? I found this DIY macro lens for cell phone cameras using a DVD player lens. Looking at the pictures from that site, it seems that this macro allows only for very, very close-up shots, so it might in fact be too close. For image processing you would need to capture the entire image of the ball, which letters you can see (N,S,E,W), and from there determine the ball orientation. If you can only see a tiny super-close-up portion of the ball, it would be harder to determine the compass orientation.

Also, I tried placing the small ball compass next to my current cell phone and noticed there are some magnetic "hot spots" where the compass won't work due to magnetic interference. So, depending on the magnetic fields around the user-facing camera, the position of the ball compass may need to be adjusted. A mirror allows more flexibility in placement of the compass.

The ball compass usage instructions actually say it should be held 8cm away from the phone to avoid magnetic interference. I'm hoping though that there will be some magnetic "dead zones" on the N900 so it won't be necessary to separate the compass from the phone (but again, a periscope mirror allows exactly such separation, though it then looks even more kludgy....)

Further investigation will probably need to wait until the N900 is available to try out various positionings of compass/lens/mirror and find a positioning that prevents magnetic interference and allows clear focusing on the ball compass.
 
Otaku is offline Otaku
2009-10-31 , 04:02
Posts: 71 | Thanked: 34 times | Joined on Sep 2009
#74
Originally Posted by wickeddeus View Post
I don't know if this has been suggested yet but why not use the same digital compass that is currently in the Iphone 3GS (and all of the Android phones, I believe)? The unit is Asahi Kasei's AK8973S. From the specs I was able to pull from the internet, the chip-size packaging is 2.5 x 2.5 x 0.5 mm. I don't know if it is technically possible but someone might be able to fit it inside a microSD body (microSD being 15 mm × 11 mm × 1 mm). It might even be possible to make the card do double duty as a digital compass plus memory storage.
I suspect that the "someone" who would be able to pull this off would have to be a professional with access to specialized ($$$) soldering/etching equipment. Imagine trying for yourself to solder a 2.5 x 2.5 x 0.5 mm chip and associated support components, and etching a board that would fit inside a microSD body - it's not something most people are likely to be able to do in their homes.

Then even if someone could do this, that leaves the problem of how to enable to rest of the communty to do the same thing, to allow a compass-enabled N900 community to exist and encourage developers to make compass-aware apps. As was pointed out earlier in the thread, compass-aware apps like AR can't take off if the compass-enabled userbase doesn't exist.

If someone could get a good automated compass production process going, and was willing to sell the resulting compasses for a reasonable price, I suspect they would get a lot of business from N900 users. However, again I think that few people in the community have the resources to pull this off. I'm willing to be surprised, though.
 
bocaJ is offline bocaJ
2009-10-31 , 05:21
Posts: 224 | Thanked: 107 times | Joined on Aug 2009
#75
I'll just put out there that I have a friend with ties to some Chinese manufacturers, who expressed some interest in an N900 project, so if there is a serious electronics engineer in the community who can accomplish the design for something like this, I would love to help arrange the mass production side.
 

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MrGrim is offline MrGrim
2009-10-31 , 07:27
Posts: 329 | Thanked: 142 times | Joined on Oct 2009
#76
Originally Posted by wickeddeus View Post
I don't know if this has been suggested yet but why not use the same digital compass that is currently in the Iphone 3GS (and all of the Android phones, I believe)? The unit is Asahi Kasei's AK8973S. From the specs I was able to pull from the internet, the chip-size packaging is 2.5 x 2.5 x 0.5 mm. I don't know if it is technically possible but someone might be able to fit it inside a microSD body (microSD being 15 mm × 11 mm × 1 mm). It might even be possible to make the card do double duty as a digital compass plus memory storage.
This isn't plumbing you know. It's not only about fitting it, it's mostly about integrating in the circuit. I somehow doubt the AKwhatever will be able do directly 'talk' to the memory controller that manages whatever is in the microSD slot. And i'm pretty sure it's simply not possible to plug something into the mainboard without having extensive knowledge about how it works. The chances you'll not break something in new and interesting ways are pretty much like winning the lottery
 
Otaku is offline Otaku
2009-10-31 , 08:00
Posts: 71 | Thanked: 34 times | Joined on Sep 2009
#77
Originally Posted by MrGrim View Post
I somehow doubt the AKwhatever will be able do directly 'talk' to the memory controller that manages whatever is in the microSD slot.
This raises an interesting question: does the N900 support microSDIO? Here, for instance, is an example of a microSDIO WiFi card, so it apparently is possible to add IO devices via microSD.
 
wickeddeus is offline wickeddeus
2009-11-02 , 17:32
Posts: 5 | Thanked: 0 times | Joined on Oct 2009
#78
Originally Posted by Otaku View Post
This raises an interesting question: does the N900 support microSDIO? Here, for instance, is an example of a microSDIO WiFi card, so it apparently is possible to add IO devices via microSD.
This is exactly what I'm talking about. I know it's not something that people can do easily. But if the community demands it someone might pick it up and built (maybe Nokia themselves). I would imagine that a microSDIO card containing a digital compass would be easier then a Wifi one. Also since the card will be in the phone then it should have no issue with orientation.
 
impatient is offline impatient
2009-11-02 , 18:16
Posts: 59 | Thanked: 28 times | Joined on Oct 2009
#79
Stick a http://www.arasan.com/products/sdioinbox/sdioinabox.php to the smallest UART electronic compass you can find and your done.
 
sarahn is offline sarahn
2009-11-03 , 05:02
Posts: 243 | Thanked: 172 times | Joined on Sep 2007 @ silicon valley
#80
Originally Posted by wickeddeus View Post
I don't know if this has been suggested yet but why not use the same digital compass that is currently in the Iphone 3GS (and all of the Android phones, I believe)? The unit is Asahi Kasei's AK8973S.
In theory nothing. In practice, do you know if you can buy less than a few thousand? It is also extremely unlikely that chip will not also require glue logic.

I picked parts based on what was available for easy prototyping and what was available in quantities of 1 on digikey.
 
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