AEGIS — Networked Rotating Ultrasonic Radar System

A radar system on the Deneyap Kart 1A (ESP32-S3). A servo sweeps an HC-SR04 ultrasonic sensor across a 180° arc; the board streams range telemetry over WebSocket and serves a full dashboard from its own flash — no external server, no app.

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How it works

Sweep and sensing run in a non-blocking loop: each step is gated by a millisecond timer, not delay(), so the WebSocket and HTTP stacks stay responsive between steps.

[Servo position] → [HC-SR04 pulse] → [distance measurement]
       ↓                                        ↓
  [LCD update]                     [WebSocket broadcast]
                                            ↓
                                   [Browser radar canvas]

Inbound commands from the dashboard arrive as JSON over WebSocket port 81 and apply to the live sweep parameters immediately — no reflash.

Offline behavior: if Wi-Fi association fails after 30 attempts (~12 seconds), the LCD shows OFFLINE MODE and the sweep loop keeps running locally. The dashboard is unreachable in that state, but ranging, detection, and the LCD readout are unaffected — the radar doesn't depend on the network being up to function.

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Features

Hardware

• Continuous 0–180° servo sweep, configurable range/speed/step
• HC-SR04 ranging to 300cm
• 1602A LCD showing live angle, distance, detection state — no clear() in the loop, so no flicker
• Falls back to local-only operation if Wi-Fi is unavailable

Dashboard (served at http://<device-ip>)

• Radar scope with sweep beam, phosphor trail, range rings
• On-canvas adjustable detection threshold
• Manual steer — click/drag on the canvas to aim the servo directly
• Threat perimeter — draw a polygon; detections inside it trigger a breach alarm
• Waterfall history strip, signal waveform panel, motion intensity meter
• Alert log with INNER/OUTER zone classification
• Sonar ping tones scaled by target distance (Web Audio API)
• System telemetry: CPU%, memory%, uptime, chip temperature
• Auto-reconnecting WebSocket — survives reload and short network drops

Firmware controls (all runtime-adjustable, no reflash)

Command	Effect
SET_SWEEP_MIN	Left boundary of sweep arc (0–180°)
SET_SWEEP_MAX	Right boundary of sweep arc (0–180°)
SET_STEP_DEG	Angular resolution per step (1–10°)
SET_STEP_DELAY	Milliseconds between steps (5–200ms)
SET_THRESHOLD	Detection distance in cm (1–300cm)
MANUAL_STEER	Point servo to a specific angle
AUTO_RESUME	Return to automatic sweep

▶ Demo video

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WebSocket protocol

One frame broadcast per sweep step on port 81.

Outbound (board → browser):

{ "a": 90, "d": 34.2, "det": true }

• a — servo angle (0–180°)
• d — distance in cm, or -1 if out of range
• det — true if within detection threshold

Inbound (browser → board): see the firmware controls table above.

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Hardware requirements

Component	Qty	Notes
Deneyap Kart 1A	1	ESP32-S3 based; other ESP32 boards need pin remapping
HC-SR04	1	5V supply required
SG90 servo	1	5V supply required; never power from board 3.3V
1602A LCD (HD44780-compatible)	1	16-pin, 4-bit parallel
MB102 breadboard power module	1	Supplies 5V to servo, sensor, LCD
9V DC wall adapter	1	Centre-positive, ≥1A. Not a PP3 battery
10kΩ potentiometer	1	LCD contrast
220Ω resistor	1	LCD backlight current limiting

Wiring

Full pin map: WIRING.md.

Deneyap pin	Connected to
D0	SG90 PWM signal
D1	HC-SR04 TRIG
D11	HC-SR04 ECHO
D4	LCD Enable
D5–D7	LCD D4–D6
D10	LCD RS
D12	LCD D7
GND	MB102 GND rail (mandatory common ground)

The MB102 GND rail must be wired to the Deneyap Kart GND pin — without a shared ground reference, signal levels are undefined.

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Software setup

1. Prerequisites

• Arduino IDE 2.x
• Deneyap Kart board package — add under File → Preferences → Additional boards manager URLs:

  https://raw.githubusercontent.com/deneyapkart/deneyapkart-arduino-core/master/package_deneyapkart_index.json
  

  then install Deneyap Kart via Tools → Board → Boards Manager.

2. Libraries

Install via Tools → Manage Libraries:

Library	Author
WebSockets	Markus Sattler
ESP32Servo	Kevin Harrington
ArduinoJson	Benoit Blanchon

LiquidCrystal and WiFi ship with the board package.

3. Wi-Fi credentials

cp firmware/aegis-deneyap/secrets.h.example firmware/aegis-deneyap/secrets.h

Edit secrets.h:

#define WIFI_SSID     "your_network_name"
#define WIFI_PASSWORD "your_password"

secrets.h is gitignored and never committed.

4. Flash

1. Open firmware/aegis-deneyap/aegis-deneyap.ino
2. Tools → Board → Deneyap Kart 1A
3. Select the correct COM port
4. Upload

On boot, the LCD shows AEGIS v1.0, then Connecting WiFi, then the board's IP address for ~3 seconds before the radar loop starts.

5. Open the dashboard

On the same Wi-Fi network:

http://<ip from LCD or serial monitor 115200>

Served directly from flash — no internet needed after first font load (or remove the Google Fonts import in dashboard.h for fully offline use).

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Project structure

aegis-embedded-system/
├── assets/
├── firmware/
│   └── aegis-deneyap/
│       ├── aegis-deneyap.ino   # Main firmware — radar loop, Wi-Fi, WebSocket
│       ├── dashboard.h         # Self-contained dashboard, stored in flash
│       ├── secrets.h           # Not committed
│       └── secrets.h.example
├── hardware/
│   ├── aegis.kicad_sch
│   ├── aegis.kicad_pcb
│   ├── aegis.kicad_pro
│   └── HC-SR04/
├── .gitignore
├── README.md
└── WIRING.md

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License

MIT — see LICENSE.

Acknowledgements

• WebSockets — Markus Sattler
• ESP32Servo — Kevin Harrington
• ArduinoJson — Benoit Blanchon
• Deneyap Kart board support — Deneyap
• HC-SR04 KiCad model — SparkFun