On the Apple M7 Motion Processor

Posted on: September 17, 2013
Posted in Mobile, Strategy

When Apple announced the iPhone 5s last week the biggest mystery was the M7 motion processor—it may have been the only unknown, as other key internals like the fingerprint sensor and possibility of a 64-bit A7 had leaked. This is interesting, showcasing that the component layer is Apple’s last stronghold of total secrecy.

The M7 is a dedicated processor with one task—to collect and process sensor data. Having an always on co-processor that consumes a tiny amount of power is a trend in mobile (the Moto X does this with other tasks too). It’s better to put the big chip (A7) in deep sleep and keep the little one going.

The M7 likely uses an extremely low power ARM core. A sensor hub connects the processor to all the sensors (i.e. gyro, accelerometers, pressure sensor, magnetic sensor). The communication standard is something simple like I2C between the sensor hub and the processor. It’s unclear who makes the sensor chip until tear down but it’s likely Atmel or STMicroelectronics.

The biggest question around the M7 is what cost / benefit will it provide to overall efficiency (performance per watt) for applications needing location / sensor data?

The M7 will actually enable massive power savings—orders of magnitude for background data collection, consuming around 1% of what the A7 would according to chip architects I’ve talked to. This will radically reduce power consumption for Fitbit-type fitness tracker applications that need to know you moved 5 miles, but don’t need to know the exact GPS coordinates you moved from / to.

However, one misconception with the M7 is that it will also reduce power in apps requiring positioning / mapping overlays and background location tracking. This is not the case.

This is because granular map-level precision will still require GPS. The M7 knows you are moving but not exactly where. What this means is that the iPhone 5s will still need to boot up the integrated GPS components (these are actually inside the Qualcomm baseband chipset). This drains orders of magnitude more power.1

The emerging question around the high end of the smartphone market is whether Apple can continue to innovate at the component level and get consumers to pay for it (A7 + M7 etc). Apple wants consumers to believe that by building its own chips, its products will have a noticeable edge in performance and battery life against the competition. This is subtle but very important. Advertise it and consumers will pay extra. This is keenly why Apple actively markets its chips, but ignores most other specs. The other open question is which Android-based phones (like the Moto X) will continue to do the same?

It is clearly evident we are at a price segmentation phase of smartphones, and this is more reason why the iPhone 5c looks like a smart product—it doesn’t use any of Apple’s latest components and is much cheaper to produce, extending Apple squarely into the mid-range. This was obviously their strategy all along—they may creep into the low end, but why dive in all at once? There are 300 million consumers in China who will decide between a mid-range and a high end phone.

Interestingly there are also new merchant chips which will enable high end Android phones to accomplish what Apple is doing with the M7—e.g. this chip. But it’s clear Apple is way ahead in having the integrated subsystem + the Core Motion frameworks all working together and ready for developers at launch.

More importantly, it’s things like the M7 that showcase Apple’s prescience in knowing how to lead in system efficiency, gains which in sum will continue to help iOS outpace Android in performance per watt by 6-18 months.

And from a more general angle, the industry lesson here continues to be that integrated software / hardware is allowing the top vendors to differentiate—smartphones are simply not following the same path as PCs and it’s really no surprise every big player is vertically integrating.

The reality is that mobile is no longer a question of whether smartphones will condense to a winner-take-all market or follow the path of computing platforms past—they won’t. The real question as the market for low, mid and high end stratifies is what percentage of consumers and which geographies will pay for differentiation.


  1. Today’s power drain for GPS is significant—around 25 mA (at a 1.8V supply) at full power when a satellite fix is obtained (more when searching for satellites). And because new satellite constellations are always being added—e.g. Beidou (Chinese) and Galilieo (EU), power in GPS subsystems will not be going down much over time, even with process shrinks. There are low power modes such as PMM/trickle power that turn the GPS radio off periodically to lower the power. But these only help a little—the fact is GPS draw a ton of current to fix on satellites. 

  • http://www.semilshah.com/ Semil Shah

    On the last paragraph, do you see iPhone 5s as an attempt to create a new top-end segment specifically?

    • http://stevecheney.com/ steve cheney

      I think having a different mid range segment makes the emerging / newest (top end) Apple products feel different for those seeking the latest. Whether illusory or not, an accentuated mid range definitely accomplishes this.

  • Ryan Jones

    Amazing work. Thank you Steve.

    Where does the 300M Chinese consumers number come from? It must be smartphones, because the total phones are ~1.1B. A link may help that point.

    What do you think could be the next sensor to get rolled into M7? Bluetooth, GPS, temp, something new? Those seem too power hungry to me.

    • http://stevecheney.com/ steve cheney

      Thanks for reading. 300M is approximately the total population of affluent consumers in China. Bluetooth and GPS will stay in the baseband chipset.

  • dang1

    still tiny screen- I can’t deal with 4 inch screen with my chubby fingers

  • http://www.isophist.com/ Emilio Orione

    The same strategy rewards the developers side too. The iPhone 5c allows current software to run well on next year new devices increasing the apps life span, while the marketing of the 5s (forward thinking) allows apps to adopt the new hardware features of the 5s with the required time, without making all the apps seem old just after the launch of the new model like has happened in past years.
    The sustaining of the platform is a key differentiation point with android, and from now on every year the apps will be ready for the new mainstream phone (today 5s will become next year 6c) supporting all its features and will have the time to support the new forward thinking phone (the 6s) in creative ways.

  • Walt French

    I’m not getting why GPS is so gawdawful expensive of power.

    Transmitters, yes. But receivers — including those GPS units in the watch-button-battery runners’ watches normally use very little.

    Some GPS units are bundled with wifi chips — at least some iPhones need to turn on wifi to enable GPS — so maybe that has more to do with the power draw.

    Still, it’d seem an easy obstacle to overcome. Even with the detailed, demanding math that I understand is part of GPS, I’m not getting why it’s such a burner — unless it’s that wifi connection.

    • http://stevecheney.com/ steve cheney

      You are directionally correct in saying that receivers don’t consume a ton of current. The truth is, 25 mA is not a lot of current, but with cell phone designers trying to squeeze as much power as they can efficiently, they always demand lower power consumption from generation to generation. Older GPS chips (2008 era) consumed a lot more power after getting a fix (>100 mA with 130 nm chips), so at 40 nm, the 25 mA is a significant improvement.

      However, with more applications using GNSS in conjunction with Wi-Fi and sensors for a hybrid location solution, the GNSS chip is actually on more often—this consumes more power. Again, there are techniques to reduce the on-time of GNSS and optimize which portions of the chipset to exercise, algorithmically. The M7 could help here by programmatically making some decisions and letting the A7 sleep.

      GPS is not really bundled with Wi-Fi in a single die, even at highly integrated vendors like Broadcom. They’ve done GPS/Bluetooth combos, but there wasn’t really a demand for this particular discrete chip combo.

      Wi-FI / Bluetooth combos are the most common. Many folks are using Broadcom for this since they lead in 802.11ac. With phones that use Qualcomm basebands, the GNSS chip is inside the baseband, while the Bluetooth / Wi-Fi combo chip is often discrete. In almost all of today’s non-Qualcomm phones, the GNSS chipset is discrete with a separate Bluetooth / Wi-Fi combo chip usually. This will only get more integrated over time. But keep in mind that analog lags digital in terms of geometry, so process can only shrink so fast for these integrated RF solutions.

      • http://www.joaopinheiro.org/ João Pinheiro

        This information is incredibly useful. I’m developing an iOS app that makes extensive use of the GPS and I’d really like to know how the current GPS chip on the iPhone 5S compares to the chips used on previous models in terms of power consumption.

        Do you happen to have any power consumption data for the gps chips used on the iPhone 5S, 5, 4S and 4?

        Thanks!

  • mark nigogosyan

    Finally! Some technical details of the M7!

    Please expand on your statement “However, one misconception with the M7 is that it will also reduce power in apps requiring positioning / mapping overlays and background location tracking”
    Consider me taking a run with my iPhone.
    I accelerate to start and go up, down and turn on my run.
    Presuming the iPhone got an accurate initial absolute position with GP, can’t one turn off the GPS,then simply use the M7 accelerometer and gyroscope?

    How closely would the true path compare to the registered one over time?
    I presume there would eventually be some divergence of the estimated and true path but by how much and at what time?
    Every 5 minutes or every day?
    Can you quantify this?
    Thank you!

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