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

iOS 26

iOS 26.1 Coming Soon: New Features for Your iPhone and Release Date

Monday October 27, 2025 7:55 am PDT by
The upcoming iOS 26.1 update includes a handful of new features and changes for iPhones, including a toggle for changing the appearance of the Liquid Glass design, "slide to stop" for alarms in the Clock app, and more. Below, we outline key details about iOS 26.1. Release Date Given that Apple has yet to seed an iOS 26.1 Release Candidate, which is typically the final beta version, the...
iOS 26

6 New Things Your iPhone Can Do in iOS 26.1

Wednesday October 29, 2025 4:22 am PDT by
Apple is about to drop iOS 26.1, the first major point release since iOS 26 was rolled out in September, and there are at least six notable changes and improvements to look forward to. We've rounded them up below. Apple has already provided developers and public beta testers with the release candidate version of iOS 26.1, which means Apple will likely roll out the update to all compatible...
maxresdefault

Apple TV 4K Could Still Launch Before 2025 Ends: All the Rumored Features

Monday October 27, 2025 4:51 pm PDT by
Apple is designing an updated version of the Apple TV 4K, and rumors suggest that it could come out sometime in the next couple of months. We're not expecting a major overhaul with design changes, but even a simple chip upgrade will bring major improvements to Apple's set-top box. Subscribe to the MacRumors YouTube channel for more videos. We've rounded up all the latest Apple TV rumors. ...
iOS 26

Apple Seeds iOS 26.1, iPadOS 26.1, and macOS Tahoe 26.1 Release Candidates

Tuesday October 28, 2025 1:07 pm PDT by
Apple today provided developers and public beta testers with the release candidate versions of upcoming iOS 26.1, iPadOS 26.1, macOS Tahoe 26.1, tvOS 26.1, watchOS 26.1, and visionOS 26.1 updates for testing purposes. The RCs betas come a week after Apple released the fourth betas. The new betas can be downloaded from the Settings app on a compatible device by going to General > Software...
M6 MacBook Pro Feature 1

M6 MacBook Pro: Release Date, Pricing, and What to Expect

Monday October 27, 2025 9:15 am PDT by
Apple this month refreshed the 14-inch MacBook Pro base model with its new M5 chip, and higher-end 14-inch and 16-inch MacBook Pro models with M5 Pro and M5 Max chips are expected to follow in early 2026. However, these machines will represent the final update to the current design, with Apple reportedly developing a completely new version of the MacBook Pro packed with next-generation hardware...
iPhone 17 Pro Cosmic Orange

8 Reasons to Wait for Next Year's iPhone 18 Pro

Thursday October 30, 2025 4:42 am PDT by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models at the same time, which is why we often get rumored features months ahead of launch. The iPhone 18 series is no different, and we already have a good idea of what to expect for the iPhone 18 Pro and iPhone 18 Pro Max. One thing worth...
macos tahoe

Here Are Apple's Release Notes for macOS Tahoe 26.1

Tuesday October 28, 2025 1:21 pm PDT by
Apple today provided developers and public beta testers with the release candidate version of macOS Tahoe 26.1, which means the update will likely see a public launch next week. The release candidate includes notes on what's in the update, so we have a full picture of the new features that Apple has included. macOS Tahoe 26.1 adds AutoMix support over AirPlay, improved FaceTime audio...
ipad mini 7 feature blue

OLED iPad Mini: Release Date, Pricing, and What to Expect

Wednesday October 29, 2025 7:13 am PDT by
Rumors are stoking excitement for the next-generation iPad mini that Apple is reportedly close to launching. So what should we expect from the successor to the iPad mini 7 that Apple released over a year ago? Read on to find out. Processor and Performance Apple is working on a next-generation version of the iPad mini (codename J510/J511) that features the A19 Pro chip, according to...
iPhone Car Key Kia

Another Vehicle Brand Gaining iPhone Car Keys Support

Tuesday October 28, 2025 5:27 am PDT by
Apple is preparing to bring support for its digital car key feature to Jetour vehicles, according to evidence uncovered on Apple's backend by MacRumors contributor Aaron Perris. Introduced in 2022, Car Keys allows an iPhone or Apple Watch to unlock a vehicle through the Wallet app. A digital version of a car key is stored in Wallet, and unlocking can be done by holding an Apple Watch or...

Top Rated Comments

wxman2003 Avatar
157 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
157 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
157 months ago
Accelerometergate! :eek:

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