Team electrabuzz

🚗 Electabuzz: Line Follower Robot Hardware Platform

A custom hardware design, PCB layout, sensor interface, and power system package for a line-following mobile robot platform.

Developed by Team Electrabuzz for UNPLUGGED — A 24-Hour Hardware Hackathon organized by DJSCE × IETE-ISF × DJS MicroMinds VLSI Club.

📸 Project Overview

⚡ Key Engineering Deliverables

• Custom Form-Factor PCB: 2-layer FR4 PCB designed in KiCad 9.0 to fit mechanical chassis boundaries, with separate ground returns for logic and motor circuits.
• Integrated Sensor & Actuator Interface: Onboard routing for an ESP32 microcontroller, 5-channel IR tracking array, TB6612FNG dual DC motor driver, 0.96" I²C OLED display, NEO-6M GPS, and ESP32-CAM module.
• Dual-Domain Power Architecture: Solar-assisted Li-ion battery charging (TP4056 + 2× 18650 cells) with LM2596 buck regulation for 5V/3.3V logic, alongside an isolated 12V motor supply rail.
• Wide-Range Isolated Power Front-End (Simulation): LTSpice SPICE simulation of a $\pm 12\text{V}$ to $\pm 50\text{V}$ DC polarity-independent isolated flyback converter with logic-level polarity telemetry.
• Design Verification: Checked with KiCad Electrical Rules Check (ERC) and Design Rules Check (DRC).

🎯 Problem & Engineering Approach

The Problem

Line-follower robots require clean sensor signal routing, reliable motor current delivery, and stable logic power. Connecting high-draw DC motors directly to the same unregulated battery rail as the microcontroller often causes voltage dips, electrical noise, and unwanted MCU resets.

The Engineering Solution

Electabuzz addresses these requirements at the board level:

1. Isolated Power Rails: Logic circuitry (ESP32, sensors, OLED) is powered via an LM2596 buck regulator from 18650 Li-ion cells, while motors are driven through a dedicated 12V rail on the TB6612FNG driver.
2. Consolidated Board Layout: Integrates power management, compute, telemetry, and motor switching onto a single PCB shaped to match chassis mounting holes.
3. Transient-Tolerant Power Simulation: A supplementary flyback converter stage was modeled to evaluate polarity-independent operation and surge clamping under wide DC input ranges.

🏗 System Architecture

                              ┌───────────────────┐
                              │  6V Solar Panel   │
                              └─────────┬─────────┘
                                        │ (1N5819 Schottky Diode)
                                        ▼
 ┌──────────────────────┐     ┌───────────────────┐
 │ 2× 18650 Li-ion      │◄───►│  TP4056 Charger   │
 │ Battery (Parallel)   │     │ (Protection IC)   │
 └──────────────────────┘     └─────────┬─────────┘
                                        │ ~3.7V - 4.2V VBAT
                                        ▼
                              ┌───────────────────┐
                              │ LM2596 Buck Conv. │──► 5.0V Logic Rail (ESP32 VIN, CAM 5V)
                              └─────────┬─────────┘
                                        │
           ┌────────────────────────────┴────────────────────────────┐
           │                                                         │
           ▼                                                         ▼
 ┌───────────────────┐                                     ┌───────────────────┐
 │ ESP32-DEVKIT-V1   │◄────────────── UART0 ──────────────►│ ESP32-CAM (OV2640)│
 │ (Main Controller) │                                     └───────────────────┘
 └───┬───┬───┬───┬───┘
     │   │   │   │
     │   │   │   └─────────── I²C (GPIO 21/22) ───────────► 0.96" SSD1306 OLED (0x3C)

🔌 Hardware Interfaces & Pin Mapping

📖 Full Details: For bus specifications and pinout notes, see Architecture Documentation.

🖥 PCB Design & Power Architecture

Schematic Capture	Copper Layer Routing (Top & Bottom)

Power System Overview

• Logic Domain (5V / 3.3V): Two 18650 Li-ion cells in parallel (~3.7V nominal) charged via a TP4056 module (with auxiliary 6V solar charging), regulated to 5.0V through an LM2596 buck converter for the ESP32 and ESP32-CAM.
• Motor Domain (12V): An external 12V power source powers the TB6612FNG VM pin, keeping motor noise and current surges off the microcontroller supply rail.

📖 Full Details: For layer stackups, see PCB Design. For power tree analysis, see Power System Documentation.

🔬 LTSpice Simulation (Bonus Challenge)

As part of the hackathon's "Brownie Points" challenge, a polarity-independent isolated flyback power supply was designed and simulated in LTSpice.

[!NOTE] Source Disclosure: The original hackathon repository included the simulation output waveform and schematic notes as an image (ltspice-flyback-output.jpeg). The standalone SPICE netlist files (polarity_protection_flyback.cir and polarity_protection_flyback.net) were reconstructed from the complete netlist text preserved in that original simulation output, allowing the circuit to be opened and executed in standard SPICE simulators.

Circuit Features

• Wide Input Range ($\pm 12\text{V}$ to $\pm 50\text{V}$): Full-bridge Schottky rectifier guarantees positive internal voltage regardless of wire orientation.
• Galvanic Isolation: $100\text{kHz}$ flyback transformer ($1:1.2$ turns ratio) provides electrical isolation between primary input and output.
• Regulated $+12.0\text{V}$ Output: $12.7\text{V}$ Zener reference and NPN emitter follower deliver a regulated $12\text{V}$ output rail.
• Polarity Telemetry: Hardware comparator outputs a $0\text{V}$ (Normal) or $5\text{V}$ (Reversed) logic signal to indicate input polarity.

📖 Full Details: For stage-by-stage equations and netlists, see Simulation Documentation.

📁 Repository Structure

Electabuzz_Unplugged/
├── .gitignore                              # KiCad, LTSpice, CAD, and OS ignore rules
├── README.md                               # Project showcase and overview
│
├── docs/                                  # Technical documentation
│   ├── architecture.md                    # System block diagrams & pin assignments
│   ├── hardware.md                        # Component specifications & mounting
│   ├── pcb-design.md                      # KiCad layout, stackup & ERC/DRC details
│   ├── power-system.md                    # Power tree & domain separation analysis
│   ├── simulation.md                      # Simulation challenge summary
│   ├── bom/                               # Manufacturing Bill of Materials
│   │   ├── README.md                      # Verified component list
│   │   ├── Bill_of_Materials.docx         # Original DOCX BOM
│   │   └── BOM.pdf                        # Original PDF BOM
│   └── assets/images/                     # Design screenshots and renders
│
├── hardware/
│   ├── pcb/                               # KiCad 9.0 PCB project files
│   │   ├── team_electrabuzz.kicad_pro     # Project master file
│   │   ├── team_electrabuzz.kicad_sch     # System schematic
│   │   └── team_electrabuzz.kicad_pcb     # PCB layout
│   └── cad/models/                        # 3D mechanical STEP models
│       ├── BK-18650-PC2--3DModel-STEP-269445.STEP
│       ├── DM-OLED096-636--3DModel-STEP-56544.STEP

🔍 Project Scope & Future Roadmap

Included in this Repository

• Complete KiCad 9.0 schematic, PCB layout, and design rule check reports.
• 3D STEP mechanical models for key onboard components.
• Manufacturing Bill of Materials (BOM) in Markdown, PDF, and DOCX formats.
• Reconstructed SPICE simulation netlists and theoretical documentation for the isolated power front-end.

Future Implementation Scope (Firmware & Software)

• Microcontroller firmware for sensor reading and motor PWM generation.
• Closed-loop line tracking algorithms (e.g., PID steering control).
• Display driver routines for real-time status output on the OLED.
• ESP32-CAM firmware integration for visual data capture.

🚀 Quickstart

Opening the PCB in KiCad

1. Install KiCad 9.0 or higher.
2. Clone this repository:

   git clone https://github.com/MayankBagad/Electabuzz_Unplugged.git

3. Open hardware/pcb/team_electrabuzz.kicad_pro in KiCad.

Running the SPICE Simulation

1. Install LTSpice or Ngspice.
2. Open simulation/polarity_protection_flyback.cir.
3. Run transient analysis (.tran 0 20m 0 1u uic).

👥 Team & Acknowledgments

• Team Electrabuzz — Hardware & PCB Design, Power Architecture
• Event: UNPLUGGED — 24-Hour Hardware Hackathon
• Organizers: DJSCE × IETE-ISF × DJS MicroMinds VLSI Club

📄 License Notice

[!NOTE] An open-source license has not yet been selected for this repository. Recommended options:

• Hardware Designs: CERN-OHL-P-2.0 (Permissive) or CC-BY-SA-4.0
• Software / Netlists: MIT License or Apache-2.0