Digital Fairy Companion

An embedded fairy companion that reacts to light, sound, touch, and color with animated expressions, synchronized audio, and mood-driven lighting.

info

Author: Ciupitu Alexandra-Isabela
GitHub Project Link: link_to_github

Description

The Digital Fairy Companion functions as a reactive embedded system that translates environmental data into interactive emotional responses to simulate a sentient digital presence. By continuously monitoring real-time inputs from light, motion, sound, color sensors and by capacitive touch interaction, the system utilizes a complex Finite State Machine to manage over seventeen distinct behavioral states. These inputs are processed by an STM32 Nucleo microcontroller which autonomously coordinates visual animations on a 2.4-inch LCD, synchronized audio responses stored on a microSD card, and dynamic ambient lighting via RGB LEDs. In practice, the system adapts its persona based on environmental triggers, such as entering a sleep state in low light or initiating a productivity timer when specific colors are detected, providing a comprehensive multi-sensory user experience.

Motivation

I chose this project because of a deep conviction that mood and mental well-being are fundamental pillars for personal growth and resilience in daily life. By merging the technical rigor of embedded systems with the whimsical charm of childhood nostalgia, I aimed to recreate the sense of magic that is often absent in standard modern technology. This project serves as a bridge between the complex mechanics of real-time sensor processing and the emotional human experience, providing a supportive companion that acknowledges and reacts to its user's environment. Ultimately, developing this system from the ground up allows me to explore how hardware and software can be harnessed not just for utility, but to foster a more mindful and enchanting atmosphere within a personal workspace.

Architecture

Components and Interconnection

The Digital Fairy Companion is structured into three primary functional modules that work in tandem to create an interactive experience:

• Sensory Module

  This layer is responsible for environmental data acquisition. It utilizes a TCS34725 for color identification, an MPU 6050 for motion and rhythm detection, a photoresistor for light intensity, an analog microphone for sound levels, and a TTP223 capacitive sensor for touch interaction. These sensors are connected to the central unit using a mix of I2C, SPI, and ADC interfaces.

• Processing & Logic Module

  At the core of the system sits the NUCLEO-U545RE-Q microcontroller, which implements a Finite State Machine (FSM) to manage over 17 distinct emotional states. It evaluates incoming sensor data to determine the appropriate behavior, such as switching from "Sleepy" to "Scared" based on sudden light and sound changes.

• Feedback & Enclosure Module

  The system produces outputs through a 2.4-inch ILI9341 LCD for pixel-art animations, a PAM8403 amplifier paired with a 1W speaker for audio, and WS2812 RGB LEDs for status-based lighting. The entire system is integrated into a thematic "Fairy House" enclosure, where the screen acts as a window and sensors are strategically hidden in decorative elements like an entrance flower or the roof.

Data & Logic Flow

Data enters the system through various protocols: I2C for complex sensory modules (Color and IMU) and SPI for high-speed communication with the LCD and SD card. The microcontroller performs real-time analysis of these inputs to trigger state transitions. Once a state is identified, the MCU retrieves corresponding graphical frames and audio clips from the microSD card and updates the visual and auditory outputs simultaneously.

Log

Week 2 - 8 March

I choosed my project idea and I thought the details of the project.

Week 13 - 19 April

I wrote the initial documentation.

Week 5 - 11 May

This week, I focused on the hardware assembly of the project. I successfully soldered the components onto the pins using a soldering iron and solder, ensuring reliable electrical connections. Additionally, I purchased a speaker to complete the audio subsystem for the device.

Week 12 - 18 May

Week 19 - 25 May

Hardware

Each component was selected to balance high performance with the low-power requirements of an always-on companion device:

• Microcontroller (MCU)

  The NUCLEO-U545RE-Q was chosen for its ultra-low-power capabilities and sufficient processing power to handle multiple serial protocols and complex FSM logic concurrently.

• Display & Storage

  The ILI9341 LCD module was selected for its vibrant color reproduction and integrated microSD slot, which simplifies the wiring for the SPI bus while providing ample storage for pixel-art assets.

• Sensors

  The TCS34725 provides superior color accuracy via I2C, while the MPU 6050 (GY-521) offers 3-axis precision for detecting physical interaction or "dizziness". The TTP223 capacitive touch sensor allows for a seamless "petting" interface without mechanical wear.

• Audio Subsystem

  To provide clear auditory feedback, the PAM8403 Class D amplifier is used to drive a compact 1W 8ohm speaker, delivering high-efficiency sound reproduction directly from the board's DAC.

• Prototyping & Power

  The system is assembled on an MB102 830-point breadboard using a combination of male-to-female and male-to-male jumper wires. Power is supplied through the USB connection of the Nucleo board, ensuring a stable 5V and 3.3V supply for all modules.

Schematics

Bill of Materials

Device	Usage	Price
ILI9341 2.4" LCD with Touch and SD Slot	Display for pixel-art animations and SD card storage	66,99 RON
TCS34725 Color Recognition Sensor	Detects ambient colors for state transitions	19,99 RON
GY-521 MPU-6050 Gyroscope + Accelerometer	Motion and rhythm detection	24,19 RON
PAM8403 Class D Audio Amplifier Module	Drives the speaker for audio feedback	5,99 RON
High Sensitivity Microphone Sound Sensor Module	Detects ambient sound levels	13,92 RON
WS2812 RGB5050 LED Module	Status-based ambient lighting	3,99 RON
LM393 Photodiode Sensor Module	Detects ambient light intensity	3,65 RON
TTP223 Capacitive Touch Sensor	Touch/petting interaction interface	1,98 RON
MB102 830-Point Breadboard	Prototyping platform	13,99 RON
400-Point Breadboard	Buttons platform	6,99 RON
40x Dupont Wires Male-Female 20cm	Connecting modules to microcontroller	6,99 RON
40x Dupont Wires Male-Male 20cm	Breadboard connections	8,99 RON
40x Dupont Wires Female-Female 30cm	Breadboard connections	6,99 RON
Mini Speaker 1W 8Ω	Audio output	18 RON
MicroSD Card	Storing graphical frames and audio clips	? RON
Tactile Push Button 6x6mm	Reset and color detection triggers	0.65 RON x 3
1x40 Pin Header 2.54mm	Connecting PAM8403 to breadboard	2 RON
NUCLEO-U545RE-Q	Main microcontroller running the FSM logic	- RON

Software

Links