ATtiny85 Sleep Position Monitor

Whenever Elite Worm sleeps on his stomach, his neck muscles feel stiff in the morning. Unfortunately he flips this way when asleep, so starting off in the right position doesn't solve things. To combat sleep-induced neck fatigue, he built a posture monitor that detects his orientation and activates a small vibration motor to alert him when he’s on his stomach.

The project is outlined in the video below, and includes some fantastic shots of him attaching tiny 0402 surface mounted components to the PCB, which allows for a very compact form factor. He's using an ATtiny85 for processing, and perhaps most impressive component implemented size-wise is a 1x1mm voltage regulator.

The device is programmed to sleep most of the time to save power, waking every eight seconds to read an accelerometer. This senses orientation, and if he’s wormed his way into a face-down position. It features a 3D-printed case and is meant to clip onto a user’s underwear band. Charging is via a USB-C port, which tops off its 100mAh, 3.7V LiPo in about an hour.

While the processor can be put to sleep, the voltage regulator and accelerometer cannot currently be switched off. This means it draws 175µA in sleep mode with the accelerometer sample rate set to minimum. The device is still very much usable, and should run for around 18 days without needing to be charge. However, this could be improved significantly, and he plans to fix these issues before potentially selling them in the future.