The Invensense has an autonomous mode (on Android devices it can count steps without bothering the host CPU) -- does the Bosch do this too?
Apple have a separate Cortex-M3 which is branded as the "M7" or "M8" motion processor. Is this what they use for step counting when the A8 is suspended? Why not use the Invensense for that? Is the M8 + Bosch less power?
>The Invensense has an autonomous mode (on Android devices it can count steps without bothering the host CPU) -- does the Bosch do this too?
IIRC there are accels that have a built in step counter (via hardware circuitry). I do not recall if Bosch has this, but the problem is that because it is a hardcoded hardware feature of the chip, it cannot be altered for customers. Apple NEVER accepts software/algoriths from its vendors. Bosch may be willing to redesign the chip with a step counter algorithm that Apple uses, but Apple would not share this with Bosch. Thus it is likely that the step counter is run on the M8 + BMA280.
They are unlikely to use the INVN autonomous step counter algorithm either. Whether the M8 + BMA280 is lower power than the MPU-6700 is something that is (a) unknowable, because we don't know the M8 specs, and (b) moot, because Apple would never use a 3rd party activity detection algorithm.
Interesting -- I thought someone with deep enough pockets could write their own DMP code for the IMVN part.
I'm sure the Android Wear devices (which mostly use the MPU-6500) must use the DMP to detect when to power on (they can't keep a Cortex-A7 juiced up just to look at gyro/accelerometer numbers), and IMVN didn't have anything like that publicly advertised a few months ago (I haven't looked more recently, and haven't inspected the Android Wear ROMs yet).
Apple have a separate Cortex-M3 which is branded as the "M7" or "M8" motion processor. Is this what they use for step counting when the A8 is suspended? Why not use the Invensense for that? Is the M8 + Bosch less power?