Wesley's Tool-Box

Last year, iPhone 5S came with a motion co-processor called M7 that can collect various sensor data relating to iPhone's motion. The most notable use for this was recording how many steps a user took while carrying the device. In other words, the device acted as a pedometer. This year, iPhone 6 series has updated the co-processor to M8 and added another sensor - a barometer. The Health app that comes with iOS 8 makes an immediate use of this. It records how many floors the user has climbed, adding another dimension of knowledge to the user's movement.


Apps that are updated to use the Healthkit in iOS 8, such as Argus, can read this stair climbing data. The notification widget from Argus is able to display the number of floors I moved up during the day if I'm using an iPhone 6 Plus. If I'm using an iPhone 5S, there's no such data available, so the widget simply doesn't mention it at all.

While I'm comparing the data from both devices, I should note is that the pedometer function acted very similarly between each other. However, as you can see in the pictures, iPhone 5S consistently recorded a bit more steps than iPhone 6 Plus, for some reason. Perhaps the bigger form factor and weight of the 6 Plus dampened the recorded movement a bit.

Probably the biggest new feature in the iPhone 5S that is completely hidden to an outside observer is Apple M7 (NXP LPC18A1), the motion coprocessor that handles a variety of sensor inputs (accelerometer, gyroscope, and compass) independent of the main processor, A7. Its main potential use is for health and fitness apps, and rightly so, they are the first apps to take advantage of it. Argus (Sept. 20) and Strava Run (Sept. 24) were updated right after iPhone 5S release to use M7. I see it as a big feature because this would enable a lot of apps to poll sensor data without draining battery much at all.

Interesting enough, when you run an app with M7 support, you'll be asked to allow access to motion activity. This is a good sense on Apple's part because these data can be easily used to track user's habits. GPS data merely tells you that a person was there. Motion activity data tells you how you were moving around there very precisely. Let's take a more careful look.