February 20, 2026
When your laptop feels your heartbeat
Reading the undocumented MEMS accelerometer on Apple Silicon MacBooks via iokit
Hidden MacBook motion sensor sparks nostalgia, panic, and pulse checks
TLDR: A developer exposed a hidden motion sensor in Apple Silicon MacBooks and even read heartbeats through desk vibrations using a simple script. Comments split between playful nostalgia (MacSaber, Newton Virus), fear of hidden sensors affecting repairs, and curiosity about what else is inside—raising fun ideas and real questions about transparency.
Your MacBook has a secret party trick: a developer tapped a hidden motion sensor in Apple Silicon laptops and streamed tiny shakes hundreds of times a second. There’s even a heartbeat demo—rest your wrists and watch your pulse pop up. It’s experimental, needs admin access, and could break in future updates; the code lives on GitHub. Not for medical use, and it may vanish in macOS.
The comments erupted. Nostalgia ruled as users shouted out MacSaber and the wild Newton Virus—proof Apple gadgets have been prank‑ready for ages. Others went full paranoia mode, worrying this “undocumented” sensor could help deny repairs: imagine a service note saying “evidence of sudden shock.”
Meanwhile, skeptics asked the detective question: How did anyone even know this sensor existed? And the tinkerers pitched weirdly brilliant ideas like using “shake your Mac” for randomness. The vibe split right down the middle: half the crowd dreams up silly motion games and desk‑drum apps; the other half side‑eyes Apple for hiding hardware behind closed doors.
Bottom line: it’s a clever, slightly spooky peek under the hood. Fun? Absolutely. Medical‑grade or reliable? Nope. But if your laptop starts feeling your heartbeat, don’t panic—just remember the internet asked for this.
Key Points
- •The project accesses an undocumented MEMS accelerometer on Apple Silicon Macs via IOKit/HID, managed by the SPU.
- •Sensor appears as AppleSPUHIDDevice (vendor usage page 0xFF00, usage 3) with AppleSPUHIDDriver; reports are 22 bytes with XYZ at offsets 6/10/14 as int32 LE, scaled by 1/65536 g.
- •Data capture is implemented using IOHIDDeviceCreate and IOHIDDeviceRegisterInputReportCallback; observed callback rate is ~100 Hz, while the project claims ~800 Hz raw data.
- •A Python tool (requires sudo) provides live readings and a heartbeat demo using ballistocardiography (0.8–3 Hz bandpass, BPM via autocorrelation).
- •Tested on a MacBook Pro M3 Pro running macOS 15.6.1; code is MIT-licensed, experimental, may break with future macOS updates, and is not for medical use.