Spectrum One – ESP32 WiFi Activity Monitor

Spectrum One is a standalone WiFi activity monitor built around the ESP32. It captures nearby 2.4 GHz packet activity and visualises signal intensity in real time using a 10-segment LED bar and a 16×2 LCD.

The device operates independently and requires only USB power. It provides a continuous physical representation of ambient WiFi traffic density.

Concept

The idea was simple: turn invisible wireless activity into a physical signal you can see on your desk.

Instead of analysing traffic through software dashboards, Spectrum One uses packet metadata (RSSI values) to create a stable visual representation of local WiFi intensity.

This is not a spectrum analyser and does not decode payload data. It measures packet presence and signal strength only.

Technical Overview

  • ESP32 configured for packet capture

  • RSSI values collected in a rolling time window

  • Averaged intensity mapped to 10-step LED bar

  • Status and metrics displayed on 16×2 LCD

  • Smoothing logic prevents unstable flicker during burst traffic

Firmware is written using ESP-IDF.

Hardware

The final version uses a custom PCB designed in KiCad.

Main components:

  • ESP32 development module

  • 10-segment LED bar array

  • 16×2 LCD (I²C interface)

  • Current-limiting resistors

  • Local decoupling

  • Tactile switch

  • JST connector

The layout prioritises clean routing, stable power delivery, and simplicity for reproducibility.

Hardware license: CERN-OHL-S
Firmware license: MIT

Development Path

  • Breadboard prototype validating packet capture

  • Signal smoothing refinement

  • Rewire for stability

  • Custom PCB design and fabrication

  • Final assembly and testing

The project evolved from experiment to documented open-hardware release.

Documentation & Files

Complete design files, firmware source, and build documentation are available.

A full PDF and EPUB book covering the entire breadboard development process — from first prototype to final PCB — is available for free download on the project page.


https://currenari.com/spectrum-one/

All hardware design files and firmware source code are released openly on GitHub.

https://github.com/currenari/spectrum-one

OSHWA UID: UK000086Full
Certified hardware version: 0.1.0