New Accelerometer Supplier Could Be Causing Incorrect iPhone 5s Level and Compass Measurements

A new supplier for the accelerometer part in the iPhone 5s could be causing incorrect level and compass measurements in the new device, an issue that was first noticed earlier this month.

RealityCap CEO Eagle Jones read into the Chipworks teardown of the iPhone 5s (via Gizmodo) and noticed that the phone uses the Bosch Sensortech BMA220 as its accelerometer. The iPhone 5, for example, used an accelerometer from STMicroelectronics.

Incorrect iPhone 5s Level

iPhone 5s and level, courtesy Gizmodo

Both devices have similar consistency in measurement, but the Bosch device has a larger measurement 'bias'. The end result, as Jones notes, is that the new accelerometer has a different 'zero-g offset' which would need to be compensated for in software.

The second key spec for accelerometers is the zero-g offset, or bias. This indicates the range for a roughly constant offset that will be added to every output sample of data due to manufacturing variance. This can also change over time due to mechanical stress or temperature variation. 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.

He goes on to note that developers can compensate for the increased offset because it is unlikely to change significantly from one measurement to another, though Apple could do a system-wide fix at the OS level to ensure accurate measurements in the future.

Related Forum: iPhone

Popular Stories

Generic iOS 19 Feature Mock Light

iOS 19 Leak Reveals All-New Design

Friday January 17, 2025 2:42 pm PST by
iOS 19 is still around six months away from being announced, but a new leak has allegedly revealed a completely redesigned Camera app. Based on footage it obtained, YouTube channel Front Page Tech shared a video showing what the new Camera app will apparently look like, with the key change being translucent menus for camera controls. Overall, the design of these menus looks similar to...
2024 App Store Awards

Apple Explains Why It Removed TikTok From the App Store in the U.S.

Sunday January 19, 2025 6:58 am PST by
Apple on late Saturday removed TikTok from the App Store in the U.S., and it has now explained why it was required to take this action. Last year, the U.S. passed a law that required Chinese company ByteDance to divest its ownership of TikTok due to potential national security risks, or else the platform would be banned. That law went into effect today, and companies like Apple and Google...
2024 iPhone Boxes Feature

Apple Changes Trade-In Values for iPhones, iPads, Macs, and More

Thursday January 16, 2025 6:45 am PST by
Apple today adjusted estimated trade-in values for select iPhone, iPad, Mac, and Apple Watch models in the U.S., according to its website. Some values increased, while others decreased. The changes were not too significant, with most values rising or dropping by $5 to $50. We have outlined some examples below: Device New Value Old Value iPhone 15 Pro Max Up to $630 U ...
Generic iOS 18

Everything New in iOS 18.3 Beta 3

Thursday January 16, 2025 12:39 pm PST by
Apple provided the third beta of iOS 18.3 to developers today, and while the betas have so far been light on new features, the third beta makes some major changes to Notification Summaries and also tweaks a few other features. Notification Summary Changes Apple made multiple changes to Notification Summaries in response to complaints about inaccurate summaries of news headlines. For...
iOS 19 Roundup Feature

iOS 19 Rumored to Be Compatible With These iPhones

Saturday January 18, 2025 10:28 am PST by
iOS 19 will not drop support for any iPhone models, according to French website iPhoneSoft.fr. The report cited a source who said iOS 19 will be compatible with any iPhone that can run iOS 18, which would mean the following models: iPhone 16 iPhone 16 Plus iPhone 16 Pro iPhone 16 Pro Max iPhone 15 iPhone 15 Plus iPhone 15 Pro iPhone 15 Pro Max iPhone 14 iPhon...
airtag 4 pack blue

AirTag 2 Launching This Year With These 3 New Features

Sunday January 19, 2025 8:11 am PST by
After a four-year wait, a new AirTag is finally expected to launch in 2025. Below, we recap rumored upgrades for the accessory. A few months ago, Bloomberg's Mark Gurman said Apple was aiming to release the AirTag 2 around the middle of 2025. While he did not offer a more specific timeframe, that means the AirTag 2 could be announced by the end of June. The original AirTag was announced...
iPhone SE Dynamic Island Majin Bu

iPhone SE 4 Leak Shows Dynamic Island, Casts Doubt on Rumored 'iPhone 16E' Name

Monday January 20, 2025 9:01 am PST by
A new iPhone SE is widely rumored to launch this year, and the device has potentially been confirmed today by known leaker Evan Blass. In a private social media post, Blass shared an image of what appears to be source code mentioning an iPhone SE (4th Gen), which casts doubt on the alternative "iPhone 16E" name rumored for the device. However, the name in the source code could be a...
iPad Pro vs iPhone 17 Air Feature

Here's How Thin the iPhone 17 Air Might Be

Friday January 17, 2025 3:38 pm PST by
For the last several months, we've been hearing rumors about a redesigned version of the iPhone 17 that Apple might call the iPhone 17 "Air," or something along those lines. It's going to replace the iPhone 17 Plus as Apple's fourth iPhone option, and it will be offered alongside the iPhone 17, iPhone 17 Pro, and iPhone 17 Pro Max. We know the iPhone 17 Air is going to be super slim, but...

Top Rated Comments

wxman2003 Avatar
147 months ago
It's amazing how someone can figure out what the problem is in a few weeks, while all of Apple engineering let this one get by them. Developers should not have to "compensate" their apps because of poor Apple QC.
Score: 15 Votes (Like | Disagree)
baryon Avatar
147 months ago
This is exactly why it shouldn't just be compensated by the same amount in every device with an update, but rather a simple "calibrate" button should be added that prompts you to use a real level and calibrate the device. Since, as they said, the bias changes over time, you probably want to recalibrate it from time to time, so it's a useful feature to add.

Every scale, measurement device, etc… even the most professional ones all have the ability to be calibrated. No one's expecting the iPhone to be accurate for this type of thing, which is one more reason to add a calibration feature.
Score: 14 Votes (Like | Disagree)
studio¹³¹ Avatar
147 months ago
Accelerometergate! :eek:

Free, uneven bumpers for all!
Score: 13 Votes (Like | Disagree)
T-Will Avatar
147 months ago
Accelerometergate! :eek:
Score: 9 Votes (Like | Disagree)
opinio Avatar
147 months ago
I don't like the angle of this story.
Score: 7 Votes (Like | Disagree)
iPhone4Jay Avatar
147 months ago
Think this could get me out of a DUI?
Score: 7 Votes (Like | Disagree)