Many iPhone 5S owners have been experiencing issues seemingly related to the handset’s on-board sensors and a new report claims the use of a new accelerometer supplier may be to blame. Following up on an earlier report, Gizmodo recently reported that a switch in Apple’s accelerometer suppliers may likely be the cause of misreadings seen in the iOS 7 Compass app.
According to a tear down by Chipworks, the iPhone 5S now uses an accelerometer made by Bosch Sensortech while older models of the smartphone employ STMicroelectronics silicon. Interestingly, STM still makes the three-axis gyroscope found in the iPhone 5S.
Since component specifications differ from manufacturer to manufacturer, the new part doesn’t behave in the same manner as those found in previous iPhones. This means apps accessing its raw data will output incorrect readings. In several anecdotal tests, the Compass app’s level was found to be off by roughly three to five percent against a physical tubular spirit measure, even after recalibration.
A more precise assessment of the discrepancy was shared by RealityCap, a company specializing in sensor-based real-time 3D location software for iOS. The company’s CEO, Eagle Jones, explained in a blog post that an accelerometer’s accuracy relies on variance or the consistency in readings and bias or constant inaccuracy due to manufacturing flaws. He had the following to say regarding the matter:
This is where we find the problem: the typical bias for the ST part is +/- 20mg, whilhttp://gizmodo.com/heres-why-the-iphone-5s-accelerometer-is-so-screwed-up-1445966306e 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.
Source: Chipworks, Gizmodo, RealityCap