The scenario
Hobbyist building a standalone audio player using an Arduino Mega, DFPlayer Mini module for MP3 playback, an I2C LCD for track info, and a rotary encoder for volume adjustment.
What is in this drawing
Read the decisions behind it.
01
Use Arduino Mega for its multiple serial ports and abundant I/O
02
DFPlayer Mini wired with software serial on pins 10 and 11
03
I2C LCD on pins A4/A5 for simplified wiring
04
Rotary encoder on digital pins 2,3,4 with pull-ups
Good reference for prototyping an interactive audio system with volume control and visual feedback.