Sensor Issues in Apple's 5S May be Linked to a New Supplier

After a story in Gizmodo seemed to prove that Apple AAPL had a motion sensor issue, one tech blogger believes he found the answer: the accelerometer.

Originally, reports began appearing on the internet noting that the new iPhone’s motion sensors were wrong specifically when it came to the phone’s leveling feature. Gizmodo compared the iPhone 5S’s readout with an old-school level sitting on top of the phone.

It found that the iPhone 5S running iOS 7 was two to three degrees off compared to the mechanical level. Other users had reported that it was off by four to six degrees.

In contrast, it performed the same test with an iPhone 5 and found that the phone and the bubble on the traditional level were nearly identical. This meant that it was likely a hardware issue—something more difficult to correct.

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Wednesday, Gizmodo published a follow-up article claiming that the problem is, indeed, in the accelerometer. In a blog post, Eagle Jones, CEO of RealityCap, noted that the accelerometer in the iPhone 5S is manufactured by Bosch Sensortech where the iPhone 5 used a STMicroelectronics part.

Big deal, right? Kind of like an auto part, brand doesn’t matter all that much. In this case, that isn’t true because each of these parts have different specs. Read the article if you’re interested in learning about high bias, low variance versus low bias, high variance but the summation is this:

“…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.”

In other words, brand matters.

RealtyCap is working on code that app developers can use to account for the issue. It says it plans to issue the fix within the coming weeks.

Apple has remained silent on the issue although according to reports, it could issue the code on its own and/or alter the phone’s firmware in phones that haven’t yet been sold.

Disclosure: At the time of this writing, Tim Parker was long Apple.