TMRh20 edited this page Jul 31, 2014 · 15 revisions

Arduino library for asynchronous playback of PCM/WAV files direct from SD card

Utilizes standard Arduino SD library, SD card and output device (Speaker, Headphones, Amplifier, etc)

###Supported Boards All 328 based boards: Arduino Uno, Nano, Duemilanove, etc
Mega Types: 1280, 2560, etc
No Due support currently.

###Recent Updates Many new features have recently been added, and are in development. See the Advanced Features wiki page


  • PCM/WAV playback direct from SD card
  • Main formats: WAV files, 8-bit, 8-32khz Sample Rate, mono.
  • Asynchronous Playback: Allows code in main loop to run while audio playback occurs.
  • Single timer operation: TIMER1 (Uno,Mega) or TIMER3,4 or 5 (Mega)
  • Complimentary output or dual speakers
  • 2x Oversampling
  • Supported devices: Arduino Uno, Nano, Mega, etc.
  • More! See the Advanced Features wiki page for additional features

Files easily converted:
Using iTunes:

Click _> Edit > Preferences > Import Settings_
Change the dropdown to _WAV Encoder_ and Setting: _Custom > 16.000kHz to 32kHz, 8-bit, Mono_
Right click any file in iTunes, and select _"Create WAV Version"_

Using Audacity:

Tracks > Stereo Track to Mono    
Project Rate (HZ) > set to 32000, 22050, 16000 or 11025    
File > Export > Save as type: Other uncompressed files > Options...    
Select WAV, Unsigned 8 bit PCM    

Then copy file to SD card using computer


TMRpcm audio;"filename");    plays a file"filename",30); plays a file starting at 30 seconds into the track
audio.speakerPin = 11;     set to 5,6,11 or 46 for Mega, 9 for Uno, Nano, etc.
audio.disable();           disables the timer on output pin and stops the music
audio.stopPlayback();      stops the music, but leaves the timer running
audio.isPlaying();         returns 1 if music playing, 0 if not
audio.pause();             pauses/unpauses playback
audio.quality(1);          Set 1 for 2x oversampling
audio.volume(0);           1(up) or 0(down) to control volume
audio.setVolume(0);        0 to 7. Set volume level
audio.loop(1);             0 or 1. Can be changed during playback for full control of looping. 

Contributed HowTo:
Details at:

Known Limitations

This library can be very processor intensive, and code execution during playback will be slower than normal
Processing load can be reduced by using lower quality sounds encoded at a lower sample rate (8khz minimum)
May interfere with other libraries that rely on interrupts. The isPlaying() disable() or noInterrupts()
 functions can be used to prevent parallel code execution.
Volume control allows good range in volume control, but will distort if volume too high


  1. Download current package:
  2. See the Manual Installation section at:

Common Issues

See the video and comments at for some tips

1. Pop or click when playback is started or stopped:
   Ramps are built into the library to prevent popping when PWM is engaged, disabled, and between music tracks of the same
   sample rate. See the [Advanced Features wiki page]( for causes and fixes.
2. Popping or clicking when music is playing
   If pops or clicks are heard during playback, it is most likely that buffer underruns are occurring or the volume is just too high.
   Ensure that #define SD_FULLSPEED is uncommented in pcmConfig.h. The value in #define buffSize 128 can be increased to provide
   additional memory for playback, which will reduce these issues. Audio can be encoded at a lower sample rate otherwise.
3. The library works fine on its own, but doesn't play when library <name> is also included.
   The first thing to check is memory usage, since nothing will work if out of memory.         
   The library uses two timer pins by default. This may interfere with other libraries that use it. (pin 10 on Arduino Uno) 
   Disable the second pin by uncommenting the line #define DISABLE_SPEAKER2 in pcmConfig.h
   Boards like Uno only have one 16-bit timer. #define USE_TIMER2 can be uncommented in pcmConfig.h if TIMER1 is required for
   something else. See the [Advanced Features wiki page](
4. Error message when compiling: "Has no member named..." or "no matching function..."
   These errors usually indicate that commands are being run which are not available in the current configuration. Check the
   #defines in pcmConfig.h to ensure you are using the correct mode(s), and ensure your commands are correct.
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