bad level

Cody recently relayed a Gizmodo report describing how an unknown portion of iPhone 5s owners have been experiencing inaccurate compass and inclinometers readings, consistently off by a noticeable margin. A huge thread on Apple’s support forums details the persistent problem.

One report Wednesday offered the most likely culprit: a change in supplier. It wasn’t immediately clear whether the issue can be fixed by way of firmware update or if some sensors are off by design, in which case Apple might replace faulty iPhone 5s units at no cost…

My first thought was that this could stem from a change in supplier.

As I reported a month ago, silicon experts over at Chipworks were able to identify the accelerometer inside the iPhone 5s as a Sensortech BMA220 unit made by Bosch, representing a notable change from the iPhone 5 which uses an accelerometer from Apple’s longtime supplier STMicroelectronics.

RealityCap agrees (via MacRumors), noting the Bosch device has a larger measurement bias, adding up to a different zero-g offset.

This is where we find the problem: the typical bias for the ST part is +/- 20mg, while the Bosch part lists +/-95mg. This almost 5x greater offset range is confirmed by our measurements, and is absolutely consistent with the failures being reported by users and the media.

Specifically, a +/- 20mg offset range would translate to around a +/-1 degree accuracy range in tilt detection, and a +/-95mg offset translates to +/-5 degrees in tilt.

RealityCap mentions that the zero-g offset can also change over time due to mechanical stress or temperature variation.

Here’s the Bosch part under Chipworks’s electron microscope.


According to Chipworks, the three-axis gyro inside the iPhone 5s is the STMicroelectronics B329 unit, as expected. As for the compass, it’s AKM’s AK8963 3-axis electronic compass IC:

The AK8963 combines a magnetic sensors to detect X, Y, and Z axis, a sensor driving circuit, arithmetic circuit and signal amplifier chain.

Here’s another shot depicting the sensor circuitry.

iPhone 5s (MEMS, Chipworks 001)

Bosch is a large German industrial company producing, among many other things, household appliances, automotive parts and technology. The Sensortech BMA220 is the first Bosch MEMS device to make its way inside any iPhone.

Further confirming RealityCap’s speculation, I’ve heard no reports about inaccurate compass and level readings plaguing iPhone 5 owners.

If these inaccuracies can be easily compensated for in software, the upcoming iOS 7.1 – perhaps due at Apple’s October 22 media event – should be able to fix the glitch.

Are your iPhone 5s readings off?

I checked mine and it seems to work as advertised.

  • mrgerbik

    it just works…

  • Mine seems to be off by the acceptable rate of 1 degree. Not that I use the compass or level often or even at all.

  • Christopher

    Mines off 3 degrees

  • deepdvd

    Every 5s that I’ve personally tested has had this issue. Which is a total of 2, but still.

  • pite

    3 degree off together with rattling lock button, iPhone sucks this time

  • Christopher

    Compass off – Randomly freezes an rebooted 3 times now – something inside my iPhone rattles when shaking lol

    • diggitydang

      I hate you for telling me this… Mine does it too… Hahahahaha…

      • Christopher

        I still love the 5s,I came from a iPhone 4 so it’s tons better lol

      • MacGuru16

        The rattle is supposed to happen, I believe. It’s the new type of vibration device they use, which also is in the iPhone 5. I thought it was an issue too last year when I got the 5, but a visit to the Genius bar soon confirmed it was meant to happen; my 5s rattles too. Unless it’s the sleep button, your phone is fine in that regard.

      • Andrieux Querido

        My 5 does not make any noise at all

  • Jared

    Mine is horrible 3-4 degrees off can’t play racing games

  • xSeriouSx

    No, you’re tilting it wrong…

  • Dennis Jones

    Mine is 3 degrees off

  • chumawumba

    Make Apple give all 5s owners a free uneven case.

  • Martynet

    I can’t believe I’m going to say this but here we go. I think I’m going to skip 5S and wait for 6. I have never skipped the new iPhone before but iPhone 5 is still a great device and will keep me going for another while I think. Btw, when is the 5S going to be released in Ireland? 😀

    • Matt

      October 25. You could wait for the 6… Or get both

  • iOops

    Mine seems to be about 1 degree off, nothing really noticeable.

  • Matthew Johnson

    Just got my iphone 5s 2 days ago and it is CONSISTENTLY off by 2 degrees. This may seem trivial to some but this absolutely RUINS many of the games I used to enjoy- if it is not fixed within days I am heading straight to the genius bar for a REFUND. I am not on contract and paid $850 for this POS. WTF Apple you are messing up big time!

  • Ghost

    So if u lost ur iPhone 5S the compass showing somewhere else lol

  • steewy01

    After a chat with apple, here is the fix. It sounds extremely bizarre to me.

    I’ll give it a go when I have some spare time.

    Did anyone tried that yet ?

    “Alright. The first step is to back up your information on your device so that you do not lose any data. Then the next step is to update to the latest software ( if you have the latest you will need to do a restore of the software in iTunes) After the update completes, allow the iPhone to charge for at least 90 minutes undisturbed with the display off and Do Not Disturb set to On. It is important that you do not move the device during this period.”

    • diggitydang

      Really? That does sound bizarre… I might give it a go when I have some time too… has anyone else tried this?

  • pite

    here is a chat with apple support:

    Update your phone. After the update completes, allow the
    phone to charge for at least 90 minutes undisturbed with the display off and Do
    Not Disturb set to On. It is important that you do not move the device during
    this period, as once the update completes, everything will recalibrate. Just
    ensure it is set flat. I can help you restore your phone and show you how to
    turn on do not disturb if you need!

    ok, but i have already 7.0.2 on it – what then?

    We can enable Do Not Disturb and charge it for
    90 minutes with the display off. If you don’t need to use your phone for the
    next hour and a half, we can set that up now. If you use it a lot, it may be
    best to wait until you plan on sleeping to do this so you don’t have to worry about
    not using it! Which works best for you?

    right, i’ll do it tonight myself – do I need to

    Actually, no! The fix came in the update, and
    we just need to get Do Not Disturb on to allow it to recalibrate.

    • steewy01

      More or less the same fix as me…

      So we don’t need to restore. Just plug the phone in with do not disturb on for 90 minutes ?

  • 4p0c4lyps3

    Mine seems to b wrking just fine in regard to the level and compass. Haven’t noticed any rattling on my old 5 or 5S either.