His phone was out of juice when he was on travel because the lightning cable broke, and he noticed the tracking upon return to home:
While traveling abroad, my iPhone cable stopped working so my 5s died completely.
I frequently use Argus to track my steps (highly recommended if you have any health bands or accessories) since it takes advantage of the M7 chip built into the phone.
Once I got back from my vacation and charged the phone, I was surprised to see that Argus displayed a number of steps for the 4 days that my phone was dead.
I’m both incredibly impressed and slightly terrified.
It should be noted that the M7 chip functions on low module independent of the A7 chip, and Argus app developer also found that it can store 7 days of step information in the internal memory, thereby displaying information about the user’s historical movement.
Because M7 relies on low-power sensors including the gyroscope, compass and accelerometer to collect activity data, it can be assumed that it doesn’t need to trigger the A7 processor and can run on the tiny charge left inside the battery after an iDevice shuts down. The devices do have some battery left to save internal storage processes, because there is still the no charge icon lighting up when you switch it on again.
What do you think?