ESP32 - Mini Mp3 Player Module
The ESP32 is a versatile 3.3V microcontroller with WiFi, Bluetooth, and multiple hardware serial ports. Combined with the DIYables Mini Mp3 Player module, you can build anything from a simple sound effect board to a WiFi-controlled jukebox.
This tutorial walks you through:
- Connecting the Mini Mp3 Player to an ESP32 — directly, without a resistor.
- Loading mp3 files onto the SD card correctly.
- Playing, pausing, resuming, stopping, and skipping tracks.
- Adjusting volume with physical buttons.
- Repeating tracks, shuffling, and organizing audio into folders.
- Monitoring playback status from your code.
Components Needed
Or you can buy the following kits:
| 1 | × | DIYables ESP32 Starter Kit (ESP32 included) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some of the links in this section are Amazon affiliate links, meaning we may earn a commission at no additional cost to you if you make a purchase through them. Additionally, some links direct you to products from our own brand, DIYables .
No resistor required. The ESP32 operates at 3.3V — the same voltage the Mini Mp3 Player's UART expects.
The Mini Mp3 Player Module
The DIYables Mini Mp3 Player is a tiny board built on the YX5200-24SS chip. It decodes mp3 files from a micro SD card, and can directly drive a speaker through its built-in 3W amplifier. Alternatively, use the DAC pins to feed an external amplifier for louder output.
Everything is controlled via serial commands at 9600 baud:
- Transport: play, pause, resume, stop, next, previous
- Volume: 31 levels (0–30)
- Equalizer: Normal, Pop, Rock, Jazz, Classic, Bass
- Repeat: loop single track, loop folder, loop all tracks, random shuffle
- Folders: play from numbered directories on the card
- Advertisements: temporarily interrupt playback, then continue
- Queries: read track number, volume, play state, track count
Pin Description
| Pin | Purpose |
|---|---|
| VCC | 3.2V to 5.0V power input |
| GND | Ground |
| RX | Serial data input (connect to ESP32 TX pin) |
| TX | Serial data output (connect to ESP32 RX pin) |
| SPK_1 | Speaker + (built-in amp, 3W max) |
| SPK_2 | Speaker − |
| DAC_R | Right channel line output |
| DAC_L | Left channel line output |
| BUSY | LOW = playing, HIGH = stopped |
| IO_1 | Short press → prev track; long press → vol down |
| IO_2 | Short press → next track; long press → vol up |
Wiring
The ESP32 uses 3.3V logic natively, so you wire the serial lines directly — no level shifting or resistors needed.
We recommend using Serial2 (available by default on most ESP32 DevKit boards):
| Mini Mp3 Player | ESP32 | Notes |
|---|---|---|
| VCC | 3.3V | Or 5V from VIN if available |
| GND | GND | |
| RX | GPIO 17 (TX2) | Direct connection |
| TX | GPIO 16 (RX2) | Direct connection |
| SPK_1 | Speaker + | |
| SPK_2 | Speaker − |
This image is created using Fritzing. Click to enlarge image
Tip: If your ESP32 variant does not expose GPIO 16/17 (some DevKit-C V4 boards use them for PSRAM), you can reassign Serial2 pins in code:
Serial2.begin(9600, SERIAL_8N1, 4, 5); // RX=GPIO4, TX=GPIO5
If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: The best way to Power ESP32 and sensors/displays.
Getting the SD Card Ready
- Format as FAT16 or FAT32.
- Place mp3 files at the root:
/001.mp3
/002.mp3
/003.mp3
- For organized playback, use numbered folders:
/01/001.mp3
/01/002.mp3
/02/001.mp3
Critical notes:
- Track numbers start at 1.
- The module indexes tracks by the order they were copied to the card, not by filename. Always format first, then copy sequentially.
- Folder names: 01–99 (2-digit), file names: 001–255 (3-digit).
Installing the Library
- Connect the ESP32 to your computer.
- In the Arduino IDE, select your ESP32 board variant and the correct port.
- Open the Libraries manager.
- Search "DIYables_MiniMp3" and install the library by DIYables.
Zero dependencies — works out of the box.
Starter Code Template
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
void setup() {
Serial.begin(115200); // Debug output
Serial2.begin(9600); // Mp3 module communication
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(25); // 0 = silence, 30 = maximum
}
void loop() {
// Add your logic
}
ESP32 Code — Play a Track
/*
* DIYables Mini Mp3 Player - Play One Track
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Plays track 001 once, then stops.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
*
* SD Card: Put mp3 files in root, named 001.mp3, 002.mp3, etc.
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
mp3.begin(Serial2);
delay(1000); // Wait for the module to initialize
mp3.setVolume(25); // Set volume (0 to 30)
Serial.println("Playing track 1...");
mp3.play(1); // Play track 001.mp3
}
void loop()
{
// Nothing to do here
}
Try It
- Load the SD card, wire the module, connect the ESP32 via USB.
- Select your ESP32 board in the IDE and upload.
Playback Control
| Method | What Happens | Code Example |
|---|---|---|
| play(n) | Plays track number n | mp3.play(1) |
| playNext() | Moves to the next track | mp3.playNext() |
| playPrevious() | Goes back one track | mp3.playPrevious() |
| pause() | Freezes playback | mp3.pause() |
| resume() | Picks up where you left off | mp3.resume() |
| stop() | Ends playback completely | mp3.stop() |
ESP32 Code — Multiple Tracks
/*
* DIYables Mini Mp3 Player - Play Multiple Tracks
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Plays tracks one after another with a delay between them.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
*
* SD Card: Put mp3 files in root, named 001.mp3, 002.mp3, 003.mp3
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
int currentTrack = 1;
int totalTracks = 3; // Change this to match your SD card
unsigned long lastTrackTime = 0;
unsigned long trackDuration = 5000; // Wait 5 seconds between tracks (adjust as needed)
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(20);
Serial.println("Playing track 1...");
mp3.play(currentTrack);
lastTrackTime = millis();
}
void loop()
{
// After trackDuration, play the next track
if (millis() - lastTrackTime >= trackDuration)
{
currentTrack++;
if (currentTrack > totalTracks)
currentTrack = 1; // Loop back to first track
Serial.print("Playing track ");
Serial.println(currentTrack);
mp3.play(currentTrack);
lastTrackTime = millis();
}
}
ESP32 Code — Next/Previous
/*
* DIYables Mini Mp3 Player - Next/Previous with Buttons
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Use two buttons to play next/previous tracks.
* Displays the current track number on the Serial Monitor.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
* Button NEXT -> Pin GPIO1 (other leg to GND)
* Button PREV -> Pin GPIO3 (other leg to GND)
*
* SD Card: Put mp3 files in root, named 001.mp3, 002.mp3, etc.
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
const int BUTTON_NEXT = 1;
const int BUTTON_PREV = 3;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
pinMode(BUTTON_NEXT, INPUT_PULLUP);
pinMode(BUTTON_PREV, INPUT_PULLUP);
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(20);
mp3.play(1); // Start with track 1
Serial.println("Press NEXT or PREV button to change track");
}
void loop()
{
if (digitalRead(BUTTON_NEXT) == LOW)
{
Serial.println("Next track");
mp3.playNext();
delay(300); // Simple debounce
}
if (digitalRead(BUTTON_PREV) == LOW)
{
Serial.println("Previous track");
mp3.playPrevious();
delay(300); // Simple debounce
}
}
ESP32 Code — Pause/Resume
/*
* DIYables Mini Mp3 Player - Pause and Resume
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Demonstrates pausing and resuming playback using a single button.
* Press the button to toggle between pause and resume.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
* Button -> Pin GPIO1 (other leg to GND)
*
* SD Card: Put mp3 files in root, named 001.mp3, 002.mp3, etc.
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
const int BUTTON_PIN = 1;
bool paused = false;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
pinMode(BUTTON_PIN, INPUT_PULLUP);
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(20);
mp3.play(1);
Serial.println("Playing. Press button to pause/resume.");
}
void loop()
{
if (digitalRead(BUTTON_PIN) == LOW)
{
if (paused)
{
mp3.resume();
Serial.println("Resumed");
}
else
{
mp3.pause();
Serial.println("Paused");
}
paused = !paused;
delay(300); // Simple debounce
}
}
ESP32 Code — Loop a Track
/*
* DIYables Mini Mp3 Player - Loop Track
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Loops (repeats) a track continuously with EQ setting.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
*
* SD Card file structure:
* /001.mp3
* /002.mp3
* ...
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
mp3.begin(Serial2);
delay(1000); // Wait for the module to initialize
mp3.setVolume(25); // Volume: 0 to 30
mp3.setEQ(DIYables_MiniMp3::EQ_NORMAL);
Serial.println("Playing track 1 on loop...");
mp3.loopTrack(1);
}
void loop()
{
// Your code here
}
Repeat & Shuffle
| Method | Behavior | Example |
|---|---|---|
| loopTrack(n) | Endlessly repeat track n | mp3.loopTrack(1) |
| loopFolder(f) | Repeat all tracks in folder f | mp3.loopFolder(1) |
| loopAll() | Repeat all tracks | mp3.loopAll() |
| stopLoop() | Cancel active loop | mp3.stopLoop() |
| shuffle() | Randomize playback | mp3.shuffle() |
ESP32 Code — Folder Playback
/*
* DIYables Mini Mp3 Player - Play from Folder
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Plays tracks from specific folders on the SD card.
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
*
* SD Card file structure:
* /01/001.mp3 <- playFolder(1, 1)
* /01/002.mp3 <- playFolder(1, 2)
* /02/001.mp3 <- playFolder(2, 1)
* /02/002.mp3 <- playFolder(2, 2)
*
* IMPORTANT:
* - Numbering starts from 1, NOT 0
* - Folder names must be 2-digit zero-padded (01-99)
* - Track names must be 3-digit zero-padded (001-255)
* - Format SD card as FAT32, then copy files one by one in order
* - Track order is determined by the order files were copied,
* NOT by filename. So copy them in the correct sequence.
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(20);
// Play track 1 from folder 01
Serial.println("Playing folder 01, track 001...");
mp3.playFolder(1, 1);
delay(5000);
// Play track 2 from folder 01
Serial.println("Playing folder 01, track 002...");
mp3.playFolder(1, 2);
delay(5000);
// Play track 1 from folder 02
Serial.println("Playing folder 02, track 001...");
mp3.playFolder(2, 1);
}
void loop()
{
// Nothing to do here
}
Folder API
| Method | Description | Example |
|---|---|---|
| playFolder(f, t) | Play track t from folder f | mp3.playFolder(1, 1) |
| playLargeFolder(f, t) | Large folder (15 folders, 3000 tracks) | mp3.playLargeFolder(1, 2000) |
| playFromMP3Folder(t) | Play from /mp3 folder | mp3.playFromMP3Folder(1) |
ESP32 Code — Serial Monitor Control
/*
* DIYables Mini Mp3 Player - Serial Command Control
*
* Product: DIYables Mini Mp3 Player Module
* https://diyables.io/products/mini-mp3-player-module
*
* Control the Mp3 player by typing commands in the Serial Monitor.
* Great for testing all functions without extra hardware.
*
* Commands (type in Serial Monitor, then press Enter):
* 1-9 Play track 1 to 9
* + Volume up
* - Volume down
* p Pause
* r Resume
* s Stop
* n Next track
* b Previous track (back)
* ? Show current status
*
* Wiring (Arduino Uno):
* Mini Mp3 RX -> ESP32 pin GPIO 17 (TX2)
* Mini Mp3 TX -> ESP32 pin GPIO 16 (RX2)
* Mini Mp3 VCC -> 5V
* Mini Mp3 GND -> GND
* Speaker connected to SPK_1 and SPK_2 pins
*
* SD Card: Put mp3 files in root, named 001.mp3, 002.mp3, etc.
*/
#include <DIYables_MiniMp3.h>
DIYables_MiniMp3 mp3;
void setup()
{
Serial.begin(9600);
Serial2.begin(9600);
mp3.begin(Serial2);
delay(1000);
mp3.setVolume(20);
Serial.println("=== DIYables Mini Mp3 Player ===");
Serial.println("Commands:");
Serial.println(" 1-9 Play track number");
Serial.println(" + Volume up");
Serial.println(" - Volume down");
Serial.println(" p Pause");
Serial.println(" r Resume");
Serial.println(" s Stop");
Serial.println(" n Next track");
Serial.println(" b Previous track");
Serial.println(" ? Show status");
Serial.println("================================");
}
void loop()
{
if (Serial.available())
{
char cmd = Serial.read();
switch (cmd)
{
case '1': case '2': case '3':
case '4': case '5': case '6':
case '7': case '8': case '9':
Serial.print("Playing track ");
Serial.println(cmd - '0');
mp3.play(cmd - '0');
break;
case '+':
Serial.println("Volume up");
mp3.volumeUp();
break;
case '-':
Serial.println("Volume down");
mp3.volumeDown();
break;
case 'p':
Serial.println("Paused");
mp3.pause();
break;
case 'r':
Serial.println("Resumed");
mp3.resume();
break;
case 's':
Serial.println("Stopped");
mp3.stop();
break;
case 'n':
Serial.println("Next track");
mp3.playNext();
break;
case 'b':
Serial.println("Previous track");
mp3.playPrevious();
break;
case '?':
{
Serial.println("--- Status ---");
int16_t vol = mp3.getVolume();
Serial.print("Volume: ");
Serial.println(vol);
int16_t track = mp3.getCurrentTrack();
Serial.print("Current track: ");
Serial.println(track);
bool playing = mp3.isPlaying();
Serial.print("Playing: ");
Serial.println(playing ? "Yes" : "No");
int16_t total = mp3.getTrackCount();
Serial.print("Total tracks: ");
Serial.println(total);
Serial.println("--------------");
break;
}
default:
break;
}
}
}
| Command | Effect |
|---|---|
| 1–9 | Play track |
| + / − | Volume |
| p / r / s | Pause / Resume / Stop |
| n / b | Next / Previous |
| ? | Status |
Equalizer Options
| Constant | ID | Character | ||
|---|---|---|---|---|
| DIYables_MiniMp3 | EQ_NORMAL | 0 | Neutral | |
| DIYables_MiniMp3 | EQ_POP | 1 | Bright | |
| DIYables_MiniMp3 | EQ_ROCK | 2 | Punchy | |
| DIYables_MiniMp3 | EQ_JAZZ | 3 | Warm | |
| DIYables_MiniMp3 | EQ_CLASSIC | 4 | Balanced | |
| DIYables_MiniMp3 | EQ_BASS | 5 | Deep |
mp3.setEQ(DIYables_MiniMp3::EQ_BASS);
Checking Module Status
These functions block for up to 100 ms while waiting for the module's reply. They return −1 if no response arrives.
| Function | Return | Description |
|---|---|---|
| isPlaying() | bool | true during active playback |
| getVolume() | int16_t | Current volume (0–30) |
| getEQ() | int16_t | Active EQ (0–5) |
| getTrackCount() | int16_t | Total tracks on SD |
| getCurrentTrack() | int16_t | Track number playing now |
| getFolderCount() | int16_t | Total folders on SD |
| getTrackCountInFolder(f) | int16_t | Tracks in folder f |