iphone 3g accelerometer not accurate?

Discussion in 'iPhone' started by bubbagumpshrimp, Aug 25, 2008.

  1. bubbagumpshrimp macrumors 6502

    Jun 16, 2008
    Just recently I downloaded A free bubble level from the app store and noticed that my accelerometer was off tilting to the left when putting it flush on a straight table (and other flat surfaces). I thought it was just the app but I noticed all of my apps that use the acc were doing the same thing. My wifes iphone interestingly performed a bit better than mine (-2.0 degrees) but was still off a little hanging to the left. One of the reasons this peaks my interest is that all of the reviews for this app claimed that it was reading accurately.

    What kind of results are you getting with your iphone acc?
    Its called "a free level" in the itunes store if you care to experiment.(Dont know how to link to the itunes store)

    Attached Files:

  2. lakaiordie macrumors 65816

    Jun 17, 2008
  3. dukebound85 macrumors P6


    Jul 17, 2005
    5045 feet above sea level
    the table may not be flat, or if it is, whos to say the ground is either?
  4. lakaiordie macrumors 65816

    Jun 17, 2008
    if you have a real ruler with the leveling bubble in it see if its the same on the same table.
  5. bubbagumpshrimp thread starter macrumors 6502

    Jun 16, 2008
    Well, even if that is the case it doesnt explain why my wifes phone would read different than mine.
  6. daihard macrumors 6502a


    Feb 19, 2008
    Seattle, WA
    My accelerometer is off to the left a bit, too. I can tell by using Cube Runner. (I believe I got this trick on this forum, but I forgot who it was.)

    Place your iPhone on a level surface and start a new game. If the accelerometer is calibrated correctly, the plane should go straight. In my case, it tilts pretty sharply to the left.

    This is the only problem I have with my iPhone, and it's not too annoying. :)
  7. effer macrumors member

    Nov 13, 2007
    My iPhone 3G's accelerometer came extremely skewed to one side. When I loaded up Dual Level, the bubble was basically stuck to the right, as if the iphone was in landscape mode to the left. After a few hours it has improved to where it is off by about 15-20 degrees. I have a replacement coming in a few days. I wonder if the problem will further correct itself.
  8. macdim macrumors 6502

    Oct 16, 2007
    So if you opened Safari, would the screen be tilted in landscape mode automatically?
  9. needthephone macrumors 6502a

    Apr 4, 2006
    I have a free spirit level app and there is a calibrate button on it so you go to a known level surface and calibrate. The iphone doesn't make a good level as it has a curved back anyway.

    But everyone is loosing the point, apple didn't really intend making the iphone into a spirit level accurate to within a fraction of a degree. The accelerometer is to sense movement, orientation and to act as a control.

    yes there are probably differences between your two iphones but is it fit for purpose? Can you use it to control games? Does the screen change from portrait to landscape when you rotate it? If the answer is Yes, your accelerometers are doing the job they were put in to do.

    So the guy above has a 'problem' with his spirit level app not being centred!! If he can proove to apple his iphone functioning as above then he doesn't have a leg to stand on re a replacement. Come on people get real here.

    I guess apple should put a note in the SDK like the GPS Turn By Turn with Google Maps-"

    The iphone must not be relied for as an accurate spirit level. No claim against apple inc will be forthcoming should your Sky Scraper fall down if you used an Apple Iphone 3G to ensure its foundations or any part of the structure of said Sky Scraper is level."

    Tip-don't rely on your iphone to be a spirit level!

    Also I don't think the term accelerometer is appropriate here aren't they orientation sensors?
  10. bubbagumpshrimp thread starter macrumors 6502

    Jun 16, 2008
    Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_0_2 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5C1 Safari/525.20)

    wow that's bad.
    Does anyone have an iPhone that is perfectly straight?
  11. needthephone macrumors 6502a

    Apr 4, 2006

    From The apple website on the acceleorometer No mention of accuracy or being used as an ACCURATE spirit level. Basically to rotate the screen and a control for games. That's all. It doesn't have to be accurate. If it was accurate to even 1 degree the iphone would cost 3 times as much as each one would have to be calibrated.

    iPhone responds to motion using a built-in accelerometer. When you rotate iPhone from portrait to landscape, the accelerometer detects the movement and changes the display accordingly. So you immediately see the entire width of a web page, view a photo in its proper aspect ratio, or control a game using only your movements.

    The accelerometer inside iPhone uses three elements: a silicon mass, a set of silicon springs, and an electrical current. The silicon springs measure the position of the silicon mass using the electrical current. Rotating iPhone causes a fluctuation in the electrical current passing through the silicon springs. The accelerometer registers these fluctuations and tells iPhone to adjust the display accordingly
  12. iNfowarrior macrumors member

    Jul 15, 2008

    I can't even begin to describe how funny this post is.

    I'm quickly beginning to think that all of the "Reported problems with the iPhone 3G" are really just the mass collection of totally inept people who now own them and act like completely clueless apes.
  13. bubbagumpshrimp thread starter macrumors 6502

    Jun 16, 2008
    Please explain because your comment is moronic as it stands.
  14. lakaiordie macrumors 65816

    Jun 17, 2008
  15. PNutts macrumors 601


    Jul 24, 2008
    Pacific Northwest, US
    I don't know when you looked at the iTunes comments, but many/most of them mention the lack of calibration for the app, the lack of factory calibration of the sensors, and differences should be expected between phones making this app mostly useless. That said, it is cool.

    There is another level app out there with calibration. It would be more interesting to see if two calibrated iPhones measure the tilt (acceleration) the same. May explain differences in game skill?
  16. rotobadger macrumors 65816


    Sep 18, 2007

    I think I might be the person you are referring to regarding using Cube Runner as a test for the accelerometer. Mine was severely tilted to the left when placed on a flat table. I took it to an Apple Genius and showed him and, without hesitation, he replaced my phone. I think what's important to point out is that, when the calibration on the accelerometer is dramatically off, it makes accelerometer driven games nearly useless. Or at least not work as intended. Considering this is a major selling point of the iPhone I would expect the accelerometer to be at least close to being accurate.
  17. rotobadger macrumors 65816


    Sep 18, 2007
    If the device is not reading orientation accurately it renders games nearly useless...or at least difficult to play. This was my experience (see my post above).
  18. t0mat0 macrumors 603


    Aug 29, 2006
    It needs a tare function perhaps. But there is a difference between accelerometer and spirit level in a way. A spirit level makes a lot of assumptions if you're using an accelerometer.
  19. Dr. Cabrera macrumors 65816

    Aug 25, 2008
    Los Angeles
    you cannot assume that a tool designed for one task would or SHOULD be accurate for another task

    much like in medicine there are drugs that have " off shelve" use, meaning they have effects that the drug was never intended to treat. Some people do not get these additional "off shelve" symptom benefits, but its not to say the drug is not effective ( it still treats the primary symptom)

    Its one thing if your accelerometer is constantly off ( constantly thinks you are moving the phone) but to have it off a few degrees, why don't you just adjust the way you hold the phone ?
  20. equlizer macrumors regular

    Aug 12, 2008
    Try the level in labyrinth lite :) Mine is 99% accurate. The only "game" that is not accurate is super monkey ball (which lots of people are complaining about)
  21. Rubberyduck macrumors newbie

    Oct 6, 2009
    Screen not level, sensor problem, can I calibrate?

    I only noticed this problem today, I decided to check out PangeaVR and loaded a few portfolios. With landscape views the horizon tilts noticeably to the right both when holding the iPhone vertically and horizontally.

    I suppose the sensor wasn't really designed for this kind of accuracy as some posters have pointed out, but it would be nice to be able to calibrate it, does anyone know how to do this.

    One fix for the Pangea app is to lock the view to Landscape or portrait but it doesn't fix the sensor issue.

    iPhone 3GS 16 Gb iOS 4

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