Reading the undocumented MEMS accelerometer on Apple Silicon MacBooks via iokit

(github.com)

38 points by todsacerdoti3 hours ago

5 comments

seductivebarry31 minutes ago
Way back in ~2008 I wrote the Newton Virus <a href="https://www.everita.com/how-the-newton-virus-was-made" rel="nofollow">https://www.everita.com/how-the-newton-virus-was-made</a> + <a href="https://www.youtube.com/watch?v=eh75j6OHhRc" rel="nofollow">https://www.youtube.com/watch?v=eh75j6OHhRc</a> (sorry for the broken images, need to update that site). Between that and using a hidden API to take screenshots of each individual element on your desktop (from icons, to taskbar, to windows) the effect was pretty believable. One of the most fun (and frustrating) projects I ever worked on.
krackers48 minutes ago
>have a hard to find mems accelerometer managed by the sensor processing unitHow did OP even know that an accelerometer exists in the first place?
- rustyhancock38 minutes ago
 The presence of the sensor is well documented as part of Apples Sudden Motion Sensor hard drive protection system.How to access it is undocumented.
 - future10se25 minutes ago
 Aaackshually, the Sudden Motion Sensor was introduced on 2005 in the PowerBook G4, and continued through the intel MacBooks with hard drives.While officially undocumented, people figured out how to access it back then, with novel uses like smacking your MacBook to change spaces (virtual desktops) or swinging the Mac around to make lightsaber noises.- <a href="https://www.youtube.com/watch?v=6uvQTTPr9Rw" rel="nofollow">https://www.youtube.com/watch?v=6uvQTTPr9Rw</a>- <a href="https://osxdaily.com/2006/12/06/macsaber-turn-your-mac-into-a-lightsaber/" rel="nofollow">https://osxdaily.com/2006/12/06/macsaber-turn-your-mac-into-...</a>(I should know, I was in university back then and swung my Mac around like an idiot, lol.)On the first Retina MacBook Pro 15" in 2012, and moving forward with all MacBooks that were SSD-only, they removed the SMS as it was not needed.To my knowledge, this is the first time we're hearing that Apple Silicon machines have an accelerometer on the SoC, officially or otherwise. It's also certainly not branded or marketed as the SMS was. (<a href="https://support.apple.com/en-us/100871" rel="nofollow">https://support.apple.com/en-us/100871</a>)Happy to be corrected on this!
 - nerdsniper17 minutes ago
 Given that current drives don't have moving parts, what function is this serving today?
- saagarjha10 minutes ago
 > the sensor lives under AppleSPUHIDDevice in the iokit registry, on vendor usage page 0xFF00, usage 3. the driver is AppleSPUHIDDriver which is part of the sensor processing unit.
userbinator54 minutes ago
undocumentedThe one thought that comes to mind is this: "Your warranty claim was denied because we determined that the laptop was subjected to a sudden shock."
- consp46 minutes ago
 Back in the days this was to lock up the hard disk read/write head. Maybe a relic from those times instead?
 - userbinator35 minutes ago
 Apple is not known for backwards-compatibility, and they were already using SSDs in their laptops long before switching to ARM.
- sysguest49 minutes ago
 idk you can just use simple liquid-container or sticker?maybe apple was preparing for "carrying-around laptop experience"?
 - XorNot44 minutes ago
 That's an entirely different product build path compared to the electronics production line though.If a pick and place machine can drop it on and reflow it, that's what you want.
 - sysguest24 minutes ago
 well it would be hardened when contact with air or somethingsee "Shipping Damage Indicators"
- altairprime49 minutes ago
 Did it park the drive heads?
greyface-1 hour ago
<a href="https://osxdaily.com/2006/12/06/macsaber-turn-your-mac-into-a-lightsaber/" rel="nofollow">https://osxdaily.com/2006/12/06/macsaber-turn-your-mac-into-...</a>
baybal21 hour ago
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