The teardown of both of Apple’s new smartphones reveals that a three-axis Bosch BMA280 accelerometer is built into the devices alongside a part from InvenSense called the MPU-6700.
The inclusion of two discrete accelerometers may initially seem odd, given the extra room and cost needed in order to put them both into the iPhone 6 and iPhone 6 Plus, but in reality it makes more sense than you think.
According to Chipworks, the InvenSense part offers a whole host of functions, and is able to work in a variety of different modes. This comes at the cost of power consumption though, which is where the less sophisticated part from Bosch comes into play. The extra power draw comes partly from the InvenSense’s improved sensitivity of 16684 LSB/g – a heady increase over the 4096 of Bosch’s offering.
It’s posited that the reason Apple has included the two points is simply down to that power consumption, and the extra time needed by the InvenSense motion sensor when it’s required to start cold. Taking 30ms to get going might not sound like a long time, but when compared to the 3ms of the Bosch, it’s an eternity. Chipworks believes that the Bosch unit will be used by iOS when sensitivity is not required but speed would be beneficial. Based on that, simple tasks such as acting as a rotation sensor for the iPhone’s screen would be perfectly suited to Bosch’s lower power consumption, with more advanced work being taken on by the InvenSense MPU-6500. That means games, for example.
The inclusion of two different accelerometers is the kind of thing that sets Apple apart from the competition. It could easily have gotten away with using just the one, but instead opted for two because it’s more elegant.
Chances are though, we’ll never notice which is which in our day-to-day lives.
Let’s wait a few more days and see what other surprises Apple has tossed into their new flagship smartphones. We’re certain there are a few things which we don’t know about at all.
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