Marvin PS

ESP32-Based 3D-Printed Toy Robot

WiFi-Controlled Robot with Animated Face, Audio, and Modular Architecture

This repository contains all development data for an ESP32-based, fully 3D-printed toy robot featuring an animated face, sound output, and WiFi control.

The project combines mechanical design, electronics, and embedded software in a modular and replication-friendly architecture. It was designed for hobbyists, education, and non-commercial use, with a strong focus on availability of components and ease of assembly.

📌 Project Overview

The robot features:

• An expressive animated face using multiple displays
• Servo-driven head and arms
• A wheeled base driven by stepper motors
• Audio input and output
• WiFi connectivity with a browser-based control interface
• Battery-powered operation with USB-C charging

All mechanical parts are fully 3D-printed and were designed using Autodesk Fusion.
The electronics are organized on two custom two-layer PCBs, avoiding SMD components to simplify manual assembly.

🤖 Key Features

• ESP32 D1 mini as main controller
• Dual 0.71” round LCD displays for animated eyes
• 0.96” OLED display for mouth animations
• MG90S servos for head rotation and arm movement
• 28BYJ-48 (5V) stepper motors for platform movement
• MPU6050 tilt and motion sensor
• INMP441 microphone (clap detection, noise level)
• MAX98357A audio amplifier with miniature speaker
• Rechargeable Li-ion battery with USB-C charging
• WiFi-based web interface for remote control
• FreeRTOS-based firmware written in C++

🧩 System Architecture

The robot is built around a two-module electronic architecture:

Head Module (PCB 1)

• ESP32 D1 mini
• Eye and mouth displays
• MPU6050 motion sensor
• Microphone and audio amplifier
• Speaker output

Body Module (PCB 2)

• Stepper motor drivers
• Battery charging controller (TP4056)
• Buck-boost converter (TPS63070, 5 V output)
• Power distribution and on/off control

Both modules are connected via a 10-pin ribbon cable.

🧠 Software Overview

The firmware is written in C++ and based on FreeRTOS.

It handles:

• Concurrent control of motors, servos, displays, and audio
• Sensor acquisition (motion, microphone)
• WiFi networking and web server
• Animation logic and behavior control

The software is built using:

• Visual Studio Code
• PlatformIO

See SYSTEM_OVERVIEW.md in the repository for detailed software documentation.

🛠 Repository Structure

marvin_robot
├─ documentation
│  ├─ datasheets
│  └─ images
│     ├─ electronics
│     ├─ eye_images
│     ├─ mechanics
│     └─ software
├─ electronics
│  ├─ marvin_MCU
│  │  ├─ marvin_MCU-backups
│  │  └─ production
│  │     └─ backups
│  └─ marvin_PS
│     ├─ marvin_PS-backups
│     └─ production
│        └─ backups
├─ mechanics
│  └─ stl_files
│     ├─ base
│     ├─ body
│     ├─ head
│     └─ legs
└─ software

🖨 3D Printing Notes

• All mechanical parts were designed in Autodesk Fusion
• STL files are provided for all parts
• 3MF files (for Bambu Lab printers) include:
  • Optimized print settings
  • Required support structures
  • Automatic pauses for inserting M2/M3 nuts

🔌 Electronics & Assembly

• Uses widely available breakout boards
• Only through-hole components
• No SMD soldering required
• Assembly order matters due to double-sided PCBs

⚡ Power & Safety

• Powered by two parallel 18650 Li-ion cells
• Charging via USB-C
• Charging and protection handled by TP4056

⚠️ Li-ion safety:
Handle batteries with care. Avoid short circuits, mechanical damage, and overheating.

📜 License

This project is open source for:

• Private use
• Education
• Learning and experimentation

❌ Commercial use is not permitted.

🙌 Credits & Tools

• Mechanical design: Autodesk Fusion
• Electronics design: KiCad
• Firmware: ESP32 + FreeRTOS
• Development environment: VS Code + PlatformIO

Happy building! 🤖✨