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.

Top Rated Comments

wxman2003 Avatar
114 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
114 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
114 months ago
Accelerometergate! :eek:

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

Popular Stories

airpods pro 2 1

AirPods Pro 2 No Longer Expected to Feature Built-In Heart Rate or Body Temperature Sensor

Sunday July 3, 2022 8:07 pm PDT by
While past rumors have indicated the upcoming second-generation AirPods Pro will feature a built-in heart rate and body temperature sensor, Bloomberg's Mark Gurman has cast doubt on those rumors turning out to be true, saying instead such a feature is unlikely to come anytime soon. "Over the past few months, there have been rumors about this year's model gaining the ability to determine a...
Apple Watch 8 Unreleased Feature Thumb

Apple Watch Series 8 Model Rumored to Feature 5% Larger Display

Monday July 4, 2022 5:50 am PDT by
Apple is working on an Apple Watch Series 8 model with a larger display, according to DSCC's Ross Young and Haitong International Securities's Jeff Pu. In October last year, Young suggested that the Apple Watch Series 8 could come in three display sizes. Now, responding to a query about the rumor on Twitter, Young claims that the additional display size joining the Apple Watch lineup will be ...
intel go pc justin long

Windows Laptop Makers 'Worried' About New MacBook Air Impacting Sales

Tuesday July 5, 2022 6:57 am PDT by
The upcoming launch of Apple's redesigned MacBook Air with the M2 chip has some Windows laptop manufacturers "worried" that sales of Intel-based laptops will be negatively affected, according to industry sources cited by DigiTimes. "A Wintel brand vendor pointed out that at a price point of US$1,000-$1,500, the MacBook Air will crowd out other high-end notebooks," the report claims, with...
European Commisssion

EU Approves Landmark Legislation to Regulate Apple and Other Big Tech Firms

Tuesday July 5, 2022 5:53 am PDT by
European Union lawmakers have approved landmark legislation to heavily regulate Apple, Google, Meta, and other big tech firms. The Digital Markets Act (DMA) and Digital Services Act (DSA) were proposed by the European Commission in December 2020. Now, collected in a "Digital Services Package," the legislation has been formally adopted by the European Parliament and seeks to address...
macbook air m2 order date feature

Apple Announces MacBook Air With M2 Chip Available to Order Starting July 8, Launches July 15

Wednesday July 6, 2022 4:59 am PDT by
Apple today announced that the new MacBook Air equipped with the M2 chip will be available to order starting Friday, July 8 at 5 a.m. Pacific Time. Apple said deliveries to customers and in-store availability will begin Friday, July 15. MacRumors exclusively reported that Apple planned to launch the new MacBook Air on July 15, and the date has now been confirmed by Apple. Customers will be...
top stories 2jul2022

Top Stories: M2 MacBook Air Release Date, New HomePod Rumor, and More

Saturday July 2, 2022 6:00 am PDT by
The M2 MacBook Pro has started making its way into customers' hands and we're learning more about how it performs in a variety of situations, but all eyes are really on the upcoming M2 MacBook Air which has seen a complete redesign and should be arriving in a couple of weeks. Other top stories this week included a host of product rumors including additional M2 and even M3 Macs, an updated...
Lockdown Mode Feature

Apple Announces New Lockdown Mode on iOS 16 With 'Extreme' Level of Security

Wednesday July 6, 2022 10:00 am PDT by
Apple today announced a new Lockdown Mode coming to the iPhone, iPad, and Mac with iOS 16, iPadOS 16, and macOS Ventura. Apple says the optional security feature is designed to protect the "very small number" of users who may be at risk of "highly targeted cyberattacks" from private companies developing state-sponsored spyware, such as journalists, activists, and government employees. Apple...
siri remote 3

Apple Releases Firmware Update for Apple TV Siri Remote

Tuesday July 5, 2022 12:10 pm PDT by
Apple today released new firmware for the Siri Remote designed for the Apple TV, updating the software from version 9M6772 to 10M1103. The software is for the redesigned Siri Remote that was released in May 2021, aka the gray remote with the updated interface. In the Apple TV settings, the new firmware will display as 0x0070, up from 0x0061. There is no word on what's new with the Apple TV...