Embedded Systems & IoT

IoT Interactive Button Lamp

A hobby project to construct a pair of internet-connected lamps with a magnet-ring rotary interface and capacitive touch control—designed, engineered, and programmed end-to-end.

Solo Build

Hobby Project

USB-C Powered

Project Overview

Exterior render of the interactive button lamp with a copper touch pad

Minimal exterior: copper capacitive touch pad centered on the rotation axis

Idea

Build two identical desk lamps that double as tactile Internet of Things (IoT) controllers. A rotating outer shell with a hidden magnet ring drives input; a capacitive copper pad provides click/hold gestures. RGB LEDs under a translucent PLA body glow through the surface for feedback and illumination.

What They Can Do

Because they’re networked, the lamps can control brightness and color, set kitchen timers, or even send color “messages” between devices anywhere in the world. As they are connected to the Arduino Cloud, they can be integrated into all Amazon, Alexa, or Google Home systems. The design avoids a traditional rotary encoder (which would be blocked by the axial touch pad) by sensing magnetic field rotation instead.

Technologies & Tools

C++ (Arduino) IoT (Wi-Fi) Hall-Effect Sensing Capacitive Touch LED Control 3D Printing (PLA) CAD & Mechanisms Electronics Manufacturing & Test

Internal render showing outer/inner housings, magnet ring, LED ring, bearings, and PCB (hall sensors not shown)

Inside the lamp: outer & inner housings, 48-magnet ring, LED ring, bearings, and control PCB (hall sensors not shown)

How It Works

Magnet-Ring Rotation Sensing

A rotating outer housing carries a ring of 48 permanent magnets. Two hall-effect sensors are mounted 41.25° apart, producing out-of-phase magnetic signals. The microcontroller compares the phase relationship to determine direction and counts zero-crossings for steps, emulating an encoder without one. Because of the axial button and housing axis, traditional rotation sensing methods could not be used.

Quadrature-style decoding from dual hall sensors
Debounce and hysteresis to reject micro-jitter
Adaptive step size for slow/fast user rotation

Magnet ring movement relative to the sensors (demonstration)

Capacitive Touch & Gestures

The top copper pad senses touch/hold/double-tap. Placing the pad on the rotation axis preserves symmetry and eliminates wiring through a spinning joint which would have required an expensive slip-ring. Gestures control modes (e.g., hold to pair, tap to confirm/send command) while rotation adjusts the selected parameters.

Touch filtering with moving average + threshold tracking
Tap/hold/double-tap gesture state machine

IoT Control & Use Cases

An IoT-enabled Arduino (ESP-class) publishes events and subscribes to commands. The pair can mirror each other’s color, act as remote dimmer knobs, or push values to home-automation systems. A single USB-C power port makes them desk-friendly.