iPhone 5s keynote (M7 specs slide)

Apple’s M7 motion tracking chip found inside the iPhone 5s, iPad Air and iPad mini with Retina display is apparently able to track a user’s motion activity even after the battery dies. According to a post by Reddit user Glarznak, his iPhone 5s was able to track his every movement even after the battery died on him. He was able to confirm this by using the Argus fitness app which showed a number of steps for the four days that his phone was dead…

As Glarznak explains (via iPhone in Canada), his iPhone 5s was left without juice while traveling abroad because his Lightning cable broke (sounds familiar?).

Upon returning home, he noticed the device continued to track his movement even though the battery was long dead.

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.

Here’s a screenshot of Argus (available free in the App Store).


I’m not sure what to make of this, but I do know the following.

Apple advertises the M7 as a low-power module that runs independently of the main A7 processor.

Chipworks identified the M7 as a rebranded NXP LPC1800 based microcontroller which runs an ARM-based Cortex-M3 core. It’s very power efficient, being able to run maxed out at about 0.6 watts at 60Mhz and 2.2 watts at 180Mhz.

We also know from a finding by the Argus app developer that the M7 stores up to seven days worth of step information in its internal memory, providing apps with a user’s historical movement information.

Argus Motion Activity access

Although idle for most people most of the time, when the M7 does run it doesn’t need to wake up the main A7 processor at all. And because it collects motion activity data from low-power sensors such as the accelerometer, compass and gyroscope (cellular and wireless communication is handled by a separate power-hungry Qualcomm chip), it’s safe to assume the M7 is capable of running on what little charge is left in the battery after the device auto-shuts down itself.

As you know, iOS devices power down automatically before the battery is completely drained. This is by design because after all, some power is needed for the shut-down procedure itself and to save the device’s and apps’ state in internal storage.

How do I know this?

Because an iOS device still displays the no charge icon if you attempt to turn it on after it powered itself down.

I’m only speculating here and your guess is as good as mine so join the conversation down in the comments because I want to hear your take on this.

Note to Glarznak: the next time you travel abroad, bring an off-the-grid charger.

  • Cameron Chao

    this is more of a good things than a bad one.

  • omrishtam


  • on3simpleclick

    NSA = M7


  • Cool, The NSA knows where you are even after your phone battery dies

    • Maxim∑

      No they don’t. The M7 processor is a very low power chip. The only reason your phone “dies” is because there is no longer enough power to run the display processor etc… It also shuts off to prevent damage to the battery. Since the M7 is independent it can continue to use power even with little battery life remaining. I highly doubt the NSA cares about how many steps your taking. If your phone shuts off due to low battery GPS/Cellular will be the last thing to still be working as it usually takes up the most power

      • jack

        a LOT of assumptions there……

    • jp2002

      It tracks your motion, not your location.

      • jack

        if you have an origin point and all the motions applied to it, you can track the path and final point position

      • I just walked 200 steps along a straight line. Which direction did I walk along?

      • Franck Kamayou

        Or walk 100 steps one way and 100 steps back… where am I?

      • Franck Kamayou

        I guess we can also estimate you location by putting a radius around you….

      • How does the M7 tell if I’m back or not?

      • What’s your starting coordinates point and what direction was your compass pointing? That’s all I need to know where you are, and that’s all the M7 co-processor utilizes…

      • How do you know that the M7 knows where I’m facing?

      • That’s what is implied by this statement:

        “And because it collects motion activity data from low-power sensors such as the accelerometer, compass and gyroscope (cellular and wireless communication is handled by a separate power-hungry Qualcomm chip)”

        With just the compass example:

        “And because it collects motion activity data from low-power sensors such as the compass, it’s safe to assume the M7 is capable of running on what little charge is left in the battery after the device auto-shuts down itself.”

        How do you interpret that? Please share…

      • Hmm… I didn’t read careful. Then I guess you are right. in theory location can be deduced from these information, although the accuracy will suffer a lot.

    • Tobias9413

      I really hope you were being sarcastic and not stupid.

      • No shit 😛 Why would anyone care if the NSA is tracking you? unless you’re like some terrorist or drug dealer

      • jack

        dont be naive

      • mjoecups

        Don’t be paranoid.

    • Tomo

      Why would I care if an American intelligence organisation can track me? I’m never going to commit a crime worth getting a government to track me, and I’m also an EU citizen.

      I’m happy the iPhone 5S is capable of this. I’m amazed, not frightened.

  • I was gonna say this isn’t a problem, more like a feature; really handy for those days you forgot to charge your MP3 player b4 going to the gym. Until I read this part:

    “And because it collects motion activity data from low-power sensors such as the accelerometer, compass and gyroscope (cellular and wireless communication is handled by a separate power-hungry Qualcomm chip)”

    WhyTF does it need location and/or cellular data? Just another fuel for the NSA conspiracy theory…

    • olvier

      so its not a problem than even if you swtch off your device or the battery dies, the phone still able to collect information? so its a feature. right. who cares what the data for or what conspiracy can be fueled by this fact. But i think something is wrong with you if you think its alright to collect info even when its switched off.

      • That’s info for counting steps, what could you do with that? I took 50 steps this early morning…but when you start connecting to a GPS or the internet, that’s far from just step counting.

    • Maxim∑

      It doesn’t but some apps use those features in combination with the basic sensors.

    • It doesn’t actually need cellular data for counting steps at all…

      • Based on that quote, it still has access to the low-power compass sensor (location data) even when it’s powered down. That’s more than enough to fuel the NSA conspiracy…there’s no other reason a “step counter” should have access to such stuff when the phone is powered down.

      • But compass only provides orientation relative to North, it does not provide exact coordinates

      • Here’s some insight into using a compass to determine location (http://bit ly/1g0q5HY)…learn something new everyday…

        As @jack pointed out, if the original location is known (which is probably acquired before your device powered down), you could just use the compass data to track their entire movement on planet Eart.

      • Rowan09

        Yes but with a compass it’s a prediction which gives you a circumference not an exact location. Nevertheless anyone with a GPS device knows they can be tracked.

      • Adam Bowman

        I’m not too sure about that, Christian. Open up the compass app and you’ll see the location indicator pop up on the status bar. At the bottom of the compass, it gives you your exact coordinates. So I wondered what would happen if I turned off location services for the compass in Settings — and I did. I then closed out the compass app in the multitasker and opened it up again. While the coordinates did not get displayed, the location indicator sure DID pop up when I opened the app. Now I’m forced to wonder if the compass does, in fact, use our location whether we know it or not. Strange.

        As far as I’m concerned, if I disable Locations for an app (native or otherwise) the location indicator icon should not pop up when I open the app.

    • Jonathan

      The point is that because the higher powered cellular and GPS are managed by a separate chip, the lower powered step counting chip can work when the phone is out of battery. If they were both by the same chip then it wouldn’t be able to count steps when out of battery. So when you say WhyTFdoes it need cellular and GPS, it doesn’t use use them to count steps at all. You’ve misread the article.

    • Rowan09

      I use Runkeeper which uses the M7 and GPS to give a more accurate reading of how fast I’m moving and distance traveled. The M7 works along with the compass and GPS but those features are not working from my understanding when the phone is dead. You can turn off location and the M7 still work without GPS.

  • Umesh N Umesh


  • Umesh N Umesh

    Good news for NSA….!!!!

  • Antzboogie

    Man I dont trust this at all. Everytime its something new we werent told Im not sure Im comfortable with this

  • Aden Bauer

    i heard if u use one of these it blocks the nsa

  • Chan

    I guess there is a miss understanding or down playing of the key feature of the M7 co-motion processor and how it behaves.

    When iPhone system shuts off there are plenty of juice left on the
    battery which keep flowing through the main board and keeps Basic Input
    Output System (BIOS) alive just as normally would when you power on the
    phone pressing the POWER button. It even powers on sometimes for another
    few minuets for an emergency call or two.

    The very key feature of the M7 processor is low power. It consumes
    very little or almost no power at all to keep it running, it may even
    run for weeks out of seemingly dead battery. Just like an LED can keep
    lighting hours out of a depleted battery.

    Of cause Apple have thought of this in advance and have introduced a
    new feature in iOS 7 called “BACKGROUND APP REFRESH” and the particular
    app in the question (Argus, also many other fitness tracking apps) in
    iPhone 5S exclusively asks for “user permission” to access the M7
    co-motion processor to keep tracking the movements in background/ idle

    So as long as there is a very little power circling the main board it
    keep powering the M7 and when an app requests the data later they can
    simply fetch it from the processor without a hitch, you have already
    given the permission to do just that. ;-D

    This is a classic example strength of Apple’s vertical hardware and software integration.

    And of cause other than this “FLIP” switch shown there are no flip
    switches in any of the mobiles to shut off physical sensors like
    compass, gyroscope, proximity sensor or the motion sensors by design
    even if the OS is shut down. They just keep working, and motion sensor
    keep logging it by design.

    This is a FEATURE by design. I hope Apple will bridge GPS and Motion
    Sensor through hardware layer and map it to the Find My Phone and that
    would be a real killer security feature!

  • AlanAudio

    While not an advertised feature, this seems pretty obvious. The M7 sips a very tiny amount of current, so even when the battery is reported as being flat, there’s still enough power to allow it to continue functioning.

    A battery is not toggle between fully charged and flat, the power remaining slowly reduces and the iPhone reports it as flat while there is still a certain amount of charge left, but not enough to allow reliable functionality. Once the main systems are turned off, that remaining charge will be available and if used frugally, will be available for many days.

    It would be interesting to see just how long the M7 keeps going for after the battery is reported as being flat.

  • If you’re worried about the NSA tracking you, then pull the plug out of your router, throw every electronic device
    you’ve ever owned and go on a retreat in a far away mountain.

    • Jonathan

      You sound like someone I know..
      Also, throw every electronic device? I think you mean throw AWAY. 🙂

    • Micaiah Martin

      Nope, I am pretty sure they have you covered 😀

    • mav3rick

      “Smart “ typical response. Pay for this overpriced device, worship it, keep it all the time with you, even bring it in your bedroom and let it record and keep a log on your life.

      How about using all electronics without keeping being tagged?

  • Brandon Weidema

    i always thought of this more as a feature.

  • Frank Lopez

    Whats more torublesome – the fact that m7 chip does this ( I think is a good thing to be honest) or the fact that argus is completely way off when it comes to tracking info?

    I walk 8-9 miles daily take about 20k+ steps I barely burn 1100 calories. Repoirted by both my fuelband and moves app.

    So either argus SUCKS! or my fuleband and moves suck and i am getting the incorrect info for 2 years now.

    • Peter Kuhar

      Hi Frank, How much off are we talking about. Could you drop me an email to peter@azumio.com to help figure a potential problem out.

  • Matt

    Well when your phone dies doesn’t mean that the battery dies because you know how when you push the power button the screen still lights up to tell you to plug it in so there still is power and since the M7 is very energy saving it doesn’t require lot of power.

  • Tony

    But even when your battery dies if you push the power button the red battery comes up. Real test would be to take the battery out of the phone completely and then see if it still tracks you.

  • NekoMichi Kobayashi

    Note that this happened when the device was “shut off” due to low power. The M7 might not do the same if the user manually powered down the device via the “Slide to Power Off”.

  • neutrino23

    This doesn’t seem totally odd. I suspect that if you fully shut down the iPhone then it would stop recording steps. If the battery is low then you haven’t explicitly shut down the device.
    One thing going on here is our perception of how devices behave. In the old days when the battery was low radios and flashlights and such would just stop working. Now we have massively more complicated devices. It makes sense that their behavior is different from naive expectations.