SENSORS/ACTUATORS

ESP32 S3 - MP3 Player

Building an MP3 player with the ESP32 S3 is a rewarding project that demonstrates how a microcontroller can control audio playback from a Micro SD Card. In this guide, you will learn how to connect a serial MP3 player module and speaker to the ESP32 S3, then program it to play, pause, and navigate between songs.

What you'll build:

A working MP3 player that reads audio files from a Micro SD Card
A system where the ESP32 S3 sends serial commands to the MP3 module
Playback control using physical buttons (play, pause, next, previous)
A foundation you can extend with volume control via potentiometer or rotary encoder

Hardware Preparation

1	×	ESP32 S3 WROOM N16R8
1	×	USB Cable Type-A to Type-C (for USB-A PC)
1	×	USB Cable Type-C to Type-C (for USB-C PC)
1	×	Serial MP3 Player Module
1	×	Micro SD Card
1	×	3.5mm Aux Speaker
1	×	Breadboard
1	×	Jumper Wires

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of Serial MP3 Player Module and Speaker

The serial MP3 player module acts as a standalone audio decoder that accepts commands over a UART serial interface, reads MP3 files from a Micro SD Card, and outputs the decoded audio signal through a 3.5mm Aux jack. Pairing it with the ESP32 S3 allows full programmatic control of playback without needing any external audio library on the microcontroller itself.

Key Specifications

Serial MP3 Player Module Pinout

The module exposes three distinct interfaces for communication, audio output, and storage.

RX pin: data input — connect to a TX pin on the ESP32 S3
TX pin: data output — connect to a RX pin on the ESP32 S3
VCC pin: power supply — connect to 3.3 V or 5 V
GND pin: ground reference — connect to GND
3.5mm Aux jack: audio output — connects directly to the speaker
Micro SD Card socket: located on the rear of the module — insert the card holding your MP3 files

Speaker Pinout

A compatible speaker typically provides two interfaces to bring audio to life.

3.5mm Aux male connector: audio signal input — plugs into the MP3 module's output jack
Power interface: USB, 5 V adapter, or any supported supply — powers the speaker's amplifier

How It Works

To get started, make sure you have the following:

Gather a collection of songs or recorded audio that you want to play and store them on a Micro SD Card.
Insert the Micro SD Card into the MP3 player module.
Connect the MP3 player module to the ESP32 S3 and connect the speaker to the MP3 player module. Also, ensure the speaker is connected to a power source.

Each MP3 file on the Micro SD Card gets an ID, starting from 0. Then, you can tell the ESP32 S3 to do various things with the MP3 player module, such as:

Play: Start playing the selected song.
Pause: Pause the song.
Play Next: Move to the next song.
Play Previous: Go back to the previous song.
Change Volume: Adjust how loud the music is.

When the MP3 player module gets a command, it reads the MP3 file from the Micro SD Card, turns it into an audio signal, and sends that signal to the speaker using a 3.5mm Aux connection.

Wiring Diagram

Connect the MP3 module's serial pins to the ESP32 S3's UART pins, and plug the speaker into the module's audio jack. Ensure that both the module and the speaker receive appropriate power before uploading your sketch.

Safety Notes

Keep signal wire runs short to reduce interference, and never connect the speaker's amplifier power directly to the ESP32 S3's 3.3 V rail — use a dedicated 5 V source to protect the board.

The wiring diagram between ESP32 S3 MP3 player module

This image is created using Fritzing. Click to enlarge image

ESP32 S3 Code - Play Music

The following code plays the first song stored on the Micro SD Card. It initialises a software serial connection to the MP3 module and sends the play command immediately on startup. The following code demonstrates the simplest possible playback scenario to verify your wiring is correct before adding controls.

Detailed Instructions

New to ESP32 S3? Complete our Getting Started with ESP32 S3 guide first.
Follow the instructions in the How It Works section above — prepare your Micro SD Card and insert it into the module.
Copy the above code and open it with Arduino IDE.
Click Upload button on Arduino IDE to upload code to ESP32 S3.
Enjoy the music.
Pro Tip: If no sound plays, double-check the RX/TX wiring polarity — the module's RX must connect to the ESP32 S3's TX pin and vice versa.

Serial Monitor Output

Open the Serial Monitor at 9600 baud to observe command acknowledgements from the MP3 module. The following readings were captured during a typical playback session.

Newbiely | Arduino IDE 2.3.8

──

☐

Newbiely.ino

···

8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'ESP32S3 Dev Module' on 'COM15')

New Line

9600 baud

[2026-06-16 10:00:01] MP3 module initialised. Playing track 1... [2026-06-16 10:00:05] Playback started successfully. [2026-06-16 10:00:45] Next track command sent. Playing track 2... [2026-06-16 10:01:30] Pause command sent. Playback paused.

Ln 11, Col 1

ESP32S3 Dev Module on COM15

ESP32 S3 Code - Play Music with Control Buttons

The following code upgrades the basic example by adding four push buttons so you can interact with the MP3 player in real time. Each button maps to a playback action — play, pause, next, and previous — giving you hands-on control without modifying the code.

/* * This ESP32 S3 code was developed by newbiely.com * * This ESP32 S3 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp32-s3/esp32-s3-mp3-player */ /* * This ESP32-S3 code is created by esp32io.com * * This ESP32-S3 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-s3-mp3-player */ #include <ezButton.h> #define CMD_PLAY_NEXT 0x01 #define CMD_PLAY_PREV 0x02 #define CMD_PLAY_W_INDEX 0x03 #define CMD_SET_VOLUME 0x06 #define CMD_SEL_DEV 0x09 #define CMD_PLAY_W_VOL 0x22 #define CMD_PLAY 0x0D #define CMD_PAUSE 0x0E #define CMD_SINGLE_CYCLE 0x19 #define DEV_TF 0x02 #define SINGLE_CYCLE_ON 0x00 #define SINGLE_CYCLE_OFF 0x01 ezButton button_play(4); // create ezButton object that attach to ESP32-S3's pin GPIO4 ezButton button_pause(5); // create ezButton object that attach to ESP32-S3's pin GPIO5 ezButton button_next(6); // create ezButton object that attach to ESP32-S3's pin GPIO6 ezButton button_prev(7); // create ezButton object that attach to ESP32-S3's pin GPIO7 void setup() { Serial.begin(9600); Serial2.begin(9600, SERIAL_8N1, 18, 17); delay(500); // wait chip initialization is complete mp3_command(CMD_SEL_DEV, DEV_TF); // select the TF card delay(200); // wait for 200ms button_play.setDebounceTime(50); // set debounce time to 50 milliseconds button_pause.setDebounceTime(50); // set debounce time to 50 milliseconds button_next.setDebounceTime(50); // set debounce time to 50 milliseconds button_prev.setDebounceTime(50); // set debounce time to 50 milliseconds } void loop() { button_play.loop(); // MUST call the loop() function first button_pause.loop(); // MUST call the loop() function first button_next.loop(); // MUST call the loop() function first button_prev.loop(); // MUST call the loop() function first if (button_play.isPressed()) { Serial.println("Play mp3"); mp3_command(CMD_PLAY, 0x0000); } if (button_pause.isPressed()) { Serial.println("Pause mp3"); mp3_command(CMD_PAUSE, 0x0000); } if (button_next.isPressed()) { Serial.println("Play next mp3"); mp3_command(CMD_PLAY_NEXT, 0x0000); } if (button_prev.isPressed()) { Serial.println("Play previous mp3"); mp3_command(CMD_PLAY_PREV, 0x0000); } } void mp3_command(int8_t command, int16_t dat) { int8_t frame[8] = {0}; frame[0] = 0x7e; // starting byte frame[1] = 0xff; // version frame[2] = 0x06; // the number of bytes of the command without starting byte and ending byte frame[3] = command; // frame[4] = 0x00; // 0x00 = no feedback, 0x01 = feedback frame[5] = (int8_t)(dat >> 8); // data high byte frame[6] = (int8_t)(dat); // data low byte frame[7] = 0xef; // ending byte for (uint8_t i = 0; i < 8; i++) { Serial2.write(frame[i]); } }

The wiring diagram for the above code:

The wiring diagram between ESP32 S3 MP3 player speaker

This image is created using Fritzing. Click to enlarge image

Now, you can modify the projects to add more functions, for example:

Add a potentiometer to control the volume, see ESP32 S3 Potentiometer tutorial
Add an IR remote controller, see ESP32 S3 IR Remote Controller tutorial
Add a RFID reader and card to make RFID MP3 player, see ESP32 S3 RFID tutorial

Applications

The ESP32 S3 MP3 player module combination is versatile enough to power many real-world audio projects. Below are some practical use cases worth exploring.

Ambient sound machine: Play looping nature sounds or white noise for relaxation or sleep aid devices.
Interactive exhibit: Trigger themed audio clips in museum or escape-room installations based on visitor actions.
Voice prompt system: Announce status messages or warnings in industrial or home-automation panels.
Educational toy: Play alphabet letters, numbers, or short lessons when a child presses a button.
Alarm and alert system: Sound custom alarm tones or spoken alerts in security or monitoring applications.

Video Tutorial

Watch the step-by-step video walkthrough for this ESP32 S3 project below.

Challenges

Extending your MP3 player project is a great way to deepen your ESP32 S3 skills. Try one of the challenges below to push the project further.

Beginner: Add an LED that blinks in sync with playback state — lit while playing, off when paused.
Intermediate: Connect a potentiometer and map its value to volume level so you can adjust loudness with a knob.
Advanced: Build a playlist manager that reads a text file from the SD card to determine playback order and allows shuffle mode via a dedicated button.

Function References

Learn More

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