iphone 5s bubble level can not be calibrated

Got the iPhone 5s and testing the new bubble level but it is off by 3-4 degrees.


On a flat surface if you stand the phone up right with the bottom of the phone on the surface, I get a perfect 0 degree with green, but if you stand it on the right side of the phone (other side of the volume button) I get 3-4 degree off. Shouldn't I get the same results unless the gyroscope sensor is off? The compass calibration doesn't seem to correct the problem.

iPhone 5s, iOS 7

Posted on Sep 23, 2013 10:07 AM

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105 replies

Oct 5, 2013 6:06 PM in response to Richard Spangler

Richard Spangler wrote:



4) never acknowledge the issue at all. It looks like they went with a lower quality accelerometer chip according to an article I read.



This is not true. We dont know the quality. According to chipworks there using a STMicroelectronics three-axis gyroscope, same as last year, a Bosch’s Sensortech BMA220, which is different than last year but we dont know the build quality. I would say that it is excellent and not the problem in my opinion.

Bosch is one of the largest sensor manufacturers if not the largest in the world. There sensors are used on everthing from automobile engines to aircraft. I doubt that Apple would have picked the lowest priced option. There is a reason in everything they do.


Semiconductor Package News website reviews the BMA220.


Here is a quote from the article: http://www.semiconductorpackagingnews.com/articles/article_21940.shtml


The reduced dimensions are not linked to a loss in functionality or quality: The BMA220, which has already been delivered in large quantities to OEM customers, is a fully fledged, triaxial g-sensor with digital data output, four programmable measuring ranges from ±2 g to ±16 g, and integrated evaluation electronics for recognizing specific motion patterns. For use in pedometers (step counters), Bosch Sensortec wrote specific evaluation algorithms tailored to the BMA220, a service that substantially shortened development time for the end device. Other applications include 3D spatial orientation in mobile telephones, PDAs and game controllers, as well as targeted reactions to movements, such as the ability to mute a ring tone by tapping twice on the mobile phone.

Oct 5, 2013 8:44 PM in response to pakum

Our family owns three 32GB Space Gray iPhone 5s'. All read different values for compass heading and level readings when carefully placed parallel to each other. Readings vary by about 10°.


Don't see the point of replacing the phones right now as there is too much chance of going from one frying pan into another. IMO.


I also have expensive Spigen screen protectors on all the phones and I'm not excited about tossing them out as a consequence of exchanging phones.


Am going outside, naked, and doing a voodoo calibration dance.


Also praying that this is a software issue.


Sweet Judy, please don't let this be a hardware defect.


Please.

Oct 6, 2013 11:37 PM in response to pakum

I'm not sure if i unterstood the exact problem, but have you tried to calibrate the phone by yourselfes ? By laying it level (on a table or so) and then touching the display once. If you do so it will show red color for a short period and after that it shows 0 degrees in level.

In addition i can assure you that this is a pure software problem because all of these sensors are influenced by drift. You need some clever algorithms to clean this drift out from time to time.


Hope this hint works for you!

Oct 6, 2013 11:57 PM in response to JohnDoe1337

All that does is enter delta mode, which is helpful if you want to measure the difference in angle. Say you're starting at a -3 angle and you want to meaure exactly 30 degrees, you'd tap the screen, the iphone would zero at -3 and you could measure more easily. It does not affect any other app other than the compass app, nor does it recalibrate the gyroscope/accelerometer on an OS level, and obce you tap the screen again you're stuck with wrong readings again. So are all other apps that rely on the motion sensors.


Could this be fixed by software? Sure you could set an offset, the problem is that many iPhone 5Ss report different "wrong" values. Mine reports -5 on a flat and levelled surface. Others reported -1 up to -8 degree readings. Then there are phones that are completely fine and those that are completely fine at first and then after a day or two start reporting wrong values.


Have a look at the video I posted earlier on how this affects users

Oct 7, 2013 3:58 AM in response to JohnDoe1337

Bad news, by tapping the screen does NOT calibrate the level but instead offsets it to 0. And besides, you'll need a level in your back pocket everytime you do this. When the offset to 0 is performed, the offset value will be 2x when the iphone if flipped over 180 degrees. Besides, it doesn't even retain it when the app is closed and restarted. I was told by Apple that it's most likely software. They're at least hoping it is. Cheers!!

Oct 7, 2013 4:04 AM in response to benfranke

I'm sorry you're absolutely right it's just a delta mode indeed.


But still it is possible to fix this problem by software. All kinds of sensors have issues like this. I used to programm a device (it was a custom pedometer) that used a three-axis-accelerometer which had an offset in the z-axis. When you took this device an hit it gently against a table the offset changed. These kinds of errors can be taken into account by calibration algorithms. I think One of the next updates provided by apple should fix it. By the way my iphone 4 also shows a small error (of 2 degree) in level.

Oct 7, 2013 7:08 AM in response to JohnDoe1337

I think a software fix is possible too, and Appl;e should get it out ASAP. I was told by an Apple Tech Supervisor that it most liely a software issue and they are well aware of it and made it a high piority. I told him I will wait it out and if it's not fixed after two more software updates, I'll be calling him back for a possible exchange. He agreed. IOS 7.0.3 (build 11B491) is due out this week, lets see if a fix is included. If they're serious about getting this fixed, it should be included.

Oct 7, 2013 9:19 AM in response to pakum

I wanted to follow-up on my post with some more hard data. Especially in light of some folks in other forums calling the reports of inaccuracies in the compass and level as "pseudo-science."


In my physics lab, I have several air tracks which can be set to level, +/- 0.01°. All three of my recently calibrated 5S's were off. By 3-5 degrees on DIFFERENT sides of horizontal. In my specific case, that was a range of 10 degrees in the reporting of level by 3 iPhone 5S's. I also used a calibrated PRO SMARTLEVEL that is accurate to +/- 0.1°. Same results.

After being placed "perfectly" parallel and calibrated, the compasses on the three phones, which are harder to test relative to a known standard, varied by 12 degrees and seemed to jump all over the place, or drift over time. Sometimes I had to shake a phone around to get it to read even a somewhat reasonable value. (A phone would initially read 355 degrees when it should have been in the 110 degree range.) All compass experiments were done outside away from sources of distortion.

I reported these results to Apple on their Feedback site.

I really don't think we're at the pseudo science level. No pun intended.

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iphone 5s bubble level can not be calibrated

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