Why iOS 9’s Facedown detection doesn’t work on iPhone 4s, iPhone 5, iPad and iPod touch

Facedown detection stands as one of the underrated features in iOS 9's rich arsenal of power-saving tactics designed to help extend your run time by up to an additional hour.

Facedown detection avoids turning the display on when a notification comes in and your phone is put facedown. But as it turns out, Facedown detection doesn't work on all devices compatible with iOS 9 and there is a good explanation for that  why.

Activity by LogYourRun helps you visualize the intensity of your activity

I'm not a slug but I'm also far from being a health freak. You won't find me at the gym, and if you ever see me running, then call 911 because it means something went terribly wrong. Yet, with the introduction of the M7 coprocessor in the iPhone 5s which helps you keep track of how many steps you made in a given day, I became more aware of little things I could do to maintain my health. I quickly established a daily goal of 6,000 steps, which I usually track with Pedometer++, a beautifully simple step tracker.

Federico Viticci of Mac Stories recently introduced me to a similar application called Activity by LogYourRun. Just like Pedometer++, Activity tracks your steps but it also helps you visualize the intensity of your activity in a very original way.

Here is the iPhone 6’s new M8 coprocessor

As expected, Apple has upgraded the M7 motion coprocessor to a new M8 motion coprocessor for the iPhone 6. This coprocessor, which exists separately from the new A8 CPU, allows the iPhone to track movements via continuous measurements from the accelerometer, gyroscope, and compass.

With the iPhone 6, the motion coprocessor's abilities have been supercharged. With the M8 the iPhone 6 can tell the difference between cycling and running. It can also calculate elevation, thanks to a new barometric sensor, and it can track distances travelled as well.