Blink controlled device

An open-source, low-cost prototype circuit that detects eye blinks to control IoT devices hands-free.

Features

1. Dual-Input Control - supports both bio-potential (blink) and manual (push-button) inputs with a priority-based logic system.
2. Active Noise Cancellation to reject 50Hz mains hum and RF interference.
3. Use it to control smart devices, play games, detect drowsiness.

Hardware

Component	Description
Microcontroller	ESP32 (DOIT DevKit V1)
Instrumentation Amplifier	AD620
Op-Amp	LM324N (optional)
Electrodes	Standard Ag/AgCl wet ECG/EOG electrodes
Feedback	LED (visual), Buzzer (audio)
Communication	Bluetooth Low Energy (BLE) – HID Keyboard

EOG placement

Code Structure

• led_eye_blink.ino – LED on/off with blinks
• dual_toggle.ino – use eye-blink or a push button (higher priority)
• drowsiness_detector.ino – blink-duration based safety system
• user_admin_blinks.ino – FreeRTOS-based admin/user priority control

Quick Start

1. Place EOG electrodes as shown above.
2. Upload eog_plotter to calibrate baseline and trigger level.
3. Update threshold values in the desired application code.
4. Upload the target sketch and power the ESP32.
5. Set the trigger threshold slightly below the blink peak to ensure reliable detection.

Schematic and PCB

Circuit Schematic	PCB Layout

3D PCB View

Limitations

Due to the use of low-cost analog components, the system remains susceptible to noise and motion artifacts.
The analog front-end is designed to attenuate these effects through filtering and proper biasing, though complete elimination is not possible at this stage.