Jellyfish Music Toy

Overview

Jellyfish is a child-friendly music toy with eight-button control, MP3 playback from SD card, song-synchronized RGB lighting, USB-C song updates, and deep-sleep battery behavior.

Highlights

• Eight-button, screen-free interaction
• Song-synced seven-color LED ring
• USB-C drag-and-drop MP3 updates
• Deep sleep with button wake-up

Challenges

• Allow song updates over USB without corrupting the SD card.
• Prevent simultaneous access when the PC and ESP32 both need the same storage.
• Make USB mode deliberate so a child cannot trigger it accidentally.
• Keep audio, buttons, LEDs, and power states reliable in a simple toy UX.

Solutions

• Gated USB mass-storage mode behind a two-second POWER hold.
• Used mount and unmount callbacks to hand SD card ownership safely between PC and firmware.
• Kept a persistent audio pipeline for responsive playback after wake.
• Implemented deep sleep so the toy consumes minimal power when idle.

Features

• Button-only play/pause, song select, and volume control
• MP3 storage on SD card
• USB-C update workflow
• Song-color mapping
• Deep-sleep idle mode

Key Results

• Created a simple no-app toy experience for children and parents.
• Reduced accidental USB-mode entry while keeping updates easy for adults.
• Delivered hardware and firmware as one integrated product.