How to Play Sound Files from SD Card with Arduino

Want your Arduino to speak or play music? You need an SD Card Module and a speaker. No expensive shield required.

Required Components

• Arduino UNO R3
• Micro SD Card Module (SPI type)
• SD Card with adapter
• Speaker 8 ohm (5W or higher)
• Breadboard and jumper wires
• Power Adapter 9V 2A (for louder output)

Wiring Connections

SD Card Module uses SPI interface connecting to Arduino as follows

SD Card Module	Arduino
CS	Pin 4
SCK	Pin 13
MOSI	Pin 11
MISO	Pin 12
VCC	5V
GND	GND

Speaker connects one leg to Pin 9 and the other to GND

Preparing SD Card and Audio Files

Arduino only supports WAV format with these specifications

// Valid audio file specs for Arduino
// - Format: WAV
// - Sampling Rate: 16000 Hz
// - Channels: Mono
// - Bit Resolution: 8-bit

Preparation steps

1. Format SD Card as FAT32
2. Convert MP3 to WAV using online-convert.com or Audacity
3. Set Sampling Rate = 16000 Hz
4. Set Channels = Mono
5. Set Bit Resolution = 8-bit
6. Name files in 8.3 format like sound.wav or 1.wav

Installing Libraries

You need two libraries

1. SD Library - Built into Arduino IDE, download if missing from Arduino Libraries
2. TMRpcm Library - For playing WAV audio files

How to install library in Arduino IDE

1. Download TMRpcm ZIP file
2. Go to Sketch > Include Library > Add .ZIP Library
3. Select the downloaded file

Arduino Code for SD Card Audio Playback

#include <SD.h>
#include <TMRpcm.h>
#include <SPI.h>

#define SD_CSPin 4      // SD Card Module CS pin
#define speakerPin 9    // Speaker pin

TMRpcm tmrpcm;          // Audio playback object

void setup() {
  Serial.begin(9600);
  
  // Initialize SD Card
  if (!SD.begin(SD_CSPin)) {
    Serial.println("SD Card initialization failed");
    return;
  }
  Serial.println("SD Card ready");
  
  // Configure speaker pin
  tmrpcm.speakerPin = speakerPin;
  
  // Set audio quality (0-7) higher values use more RAM
  // UNO can handle up to 4 without freezing
  tmrpcm.setVolume(5);
  
  Serial.println("Type filename (without .wav) and press Send");
}

void loop() {
  if (Serial.available()) {
    String filename = Serial.readStringUntil('\n');
    filename.trim();
    
    // Append .wav extension
    if (!filename.endsWith(".wav")) {
      filename += ".wav";
    }
    
    Serial.print("Playing: ");
    Serial.println(filename);
    
    if (!tmrpcm.play(filename.c_str())) {
      Serial.println("Playback failed. Check filename in SD Card");
    }
  }
}

How to Use

1. Upload code to board
2. Open Serial Monitor (baud rate 9600)
3. Insert SD Card with audio files like 1.wav
4. Type 1 and press Send
5. Arduino plays sound through speaker immediately

Common Problems

Audio distorts or skips

• Lower Bit Resolution to 8-bit
• Reduce Sampling Rate to 16000 Hz
• Add 100uF capacitor across speaker terminals

File won’t play

• Verify filename is correct (case-sensitive)
• Check SD Card is formatted as FAT32
• Try another file to confirm proper conversion

Speaker too quiet

• Use 8 ohm speaker rated 5W or higher
• Increase volume in code tmrpcm.setVolume(7);
• Use Power Adapter instead of USB for power

Summary

Playing audio files from SD Card with Arduino is straightforward. Just need SD Card Module, speaker, and TMRpcm library. Limitation is it only supports WAV files with audio quality not matching MP3 players, but it’s sufficient for voice prompts or narration projects.