Sparkfun MP3 Shield Arduino Library

Posted in Arduino Libraries by Bill
28 Jan 2012

The Sparkfun MP3 Player Shield for Arduino is a inexpensive and easy way to add MP3 playback capability to your Arduino project. But it was lacking an easy to use Arduino Library to go along, so I fixed that. Introducing the SFEMP3Shield library just for this shield. Now playing an MP3 files is as easy as MP3player.playTrack(5); and all the work is done behind the scenes.

Most of this library comes from the existing example code, with the major new feature of being interrupt driven. So no need to worry about feeding the MP3 chip, whenever it’s ready for more the library will be ready to feed it. This allows the Arduino to perform other tasks while music is playing. The most basic use of the library is as follows:

 

#include <SPI.h>
#include <SdFat.h>
#include <SdFatUtil.h> 
#include <SFEMP3Shield.h>

SdFat sd;
SFEMP3Shield MP3player;

void setup() {

  Serial.begin(9600);

  //start the shield
  sd.begin(SD_SEL, SPI_HALF_SPEED);
  MP3player.begin();

  //start playing track 1
  MP3player.playTrack(1);
}

//do something else now
void loop() {

  Serial.println("I'm bored!");
  delay(2000);

}

That’s all it takes to get your Arduino to play an MP3 file using the shield.  How easy is that?

The library does have more functions and even error reporting. All of which can be found in the ReadMe file or in the Example Sketch included with the Library.

Source Code available on GitHub project pages: Sparkfun MP3 Player Shield Arduino Library

Or Direct Download here.

Using the SPI bus for something else as well?

I added some functions to make sure there will be no data collisions on the SPI bus caused by the MP3 decoder asking for more data at the wrong time. You need to wrap any SPI code you add to your project with these two functions. Here’s an example from my project that also has a shift register on the SPI bus:

  //disable interrupts to avoid collisions on the SPI bus between this code //and the MP3player library
  MP3player.pauseDataStream();

  //shift data
  tempIO = SPI.transfer(HIBYTE(output));
  tempIO<<8; 
  tempIO = SPI.transfer(LOBYTE(output));

  //latch output on shift registers
  digitalWrite(OUTLATCH,LOW);
  digitalWrite(OUTLATCH,HIGH);
  digitalWrite(OUTLATCH,LOW);

  //enable interrupts
  MP3player.resumeDataStream();

But you can’t stop the data stream to the MP3 Shield for too long before it runs out of data so be careful and try not to do too much stuff in between the functions.

 

Wanna be your own DJ?

New features! Requested in the comments below, there are now functions to skip around a playing track. You could fast forward, rewind, create loops, etc.

Here’s an example that will just open a file, jump to the 30 second mark (measured in milliseconds, 30 seconds = 30000 ms), and loop the song back every 750 ms:

MP3player.playTrack(1);

for(;;) {
MP3player.skipTo(30000);
delay(750);
}

If you want to know where you are in the current playback, do this:

time = MP3player.currentPosition();
Serial.println(time);

Both functions are not super accurate and depend on the bitrate of the file. The library should auto-detect the bitrate of the file but may fail on some MP3 files. If that happens, you have to set the bitrate manually like this:

MP3player.playTrack(1);
MP3player.setBitRate(192);

I can already see the cool DIY DJ equipment that could be made with this. Let me know if you have problems, and comment below if you ever make something cool with the library.

Troubleshooting

Pulled from the GitHub Project Page

The below is a list of basic questions to ask when attempting to determine the problem.

  • Did it initially PRINT the available RAM and Full Help Menu?
    • The MP3Shield_Library_Demo.ino example should initially provide a opening print indicating the amount of available SRAM and full menu help. If you don’t see this the problem is between your Target and IDE. And likely not this library
    • Is Serial Monitor set to the correct tty or com port and 115200 baud rate? Did you change the baud rate?
    • Reset the Arduino after Serial Monitor is open or send any key. It may have printed these prior to the Serial Monitor being started.
  • WHAT is the Error reported?
    • Is the Error Code is indicating a file problem.
    • Are the filenames 8.3 format? See below warning.
    • See also Error Codes
  • Did the SdCard LOAD?
    • Try reseating your SdCard.
  • Is it FAT(FAT16 or FAT32)?
    • If the Error Code is indicating problems with the INIT, VOLUME or Track not being successful. It is recommend to use SdFat Example Library’s QuickStart.ino as to see if it can access the card. Additionaly, SdInfo.ino may indicate if it can mount the card. Which may then need to formatted in FAT16 or FAT32. Where SdFormatter.ino can do this for you.
  • Are the needed files on the root?
    • Remember to put patch and audio track files on the SdCard after formatting.
    • Are the filenames 8.3 format? See below warning.
  • "Error code: 1 when \b trying to play track"
    • See the above Limitations. about Non-Blocking.
    • Remember to check your audio cables and volume.
  • Why do I only hear1 second of music, or less?
    • This symptom is typical of the interrupt not triggering the SFEMP3Shield::refill(). I bet repeatidly sendnig a track number will advance the play about one second at a time, then stop.
    • What board is it? Check Hardware Limitations. about Interrupts.
    • Are you trying the SFE provided test files ? Or some homemade mp3 files? The SFE test files are nice as they are Immediately LOUD.
    • Interrupt problems may cause mp3 files that have a quiet lead in (or ramp up of volume) to be falsely diagnosed as not playing at all. Where the first 1 second may not be loud enough to be heard.
  • Free RAM = 1090 Should be a base line of 1094
    • As a courtesy and good practice the provided example MP3Shield_Library_Demo.ino prints out the available remaining RAM, not statically allocated. And the actual available amount may depend on specific processor, IDE version, libraries and or other factors. A Uno built with IDE version 1.0.2 should have approximately 1094 bytes available from the example as is. And a Mega using a 2560 may show 6713, as it has more RAM.

Note

This library makes extensive use of SdFat Library as to retrieve the stream of audio data from the SdCard. Notably this is where most failures occur. Where some SdCard types and manufacturers are not supported by SdFat. Though SdFat Lib is at this time, supporting most known cards.

 

Warning

SdFatLib only supports 8.3 filenames. Long file names will not work. Use the 'd' menu command to display directory contents of the SdCard. "longfilename.mp3" will be converted to "longfi~1.mp3" . Where one can not predict the value of the 1. The DOS command of "dir \c /x" will list a cross reference, so that you know exactly, what is what.

Still Need Help?

Use the support forum to look for a solution or ask for help. Please don’t use the comments below to ask for help.

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  1. 552 Comments.

    • Michael P. FlagaNo Gravatar says:

      refer to the WebPlayer Example at https://github.com/mpflaga/Sparkfun-MP3-Player-Shield-Arduino-Library/blob/master/SFEMP3Shield/Examples/WebPlayer/WebPlayer.ino along with the Documentation at http://mpflaga.github.io/Sparkfun-MP3-Player-Shield-Arduino-Library/ and read the support forum. Like an issue with a Chip Select conflict between the two shields.

    • Brendan WertanenNo Gravatar says:

      Hey Bill,

      We recently purchased the MP3 shield for a project to use with an Arduino Mega. I have read through all of the comments and suggestions about the proper way to unzip and place the libraries that you have created.

      For some reason we cannot get the example code to compile and we only receive multiple errors with the SdSpi not having a type and the SD_CHIP_SELECT_PIN not being declared in the scope. When the libraries are included, only the SPI library is recognized and turns orange. Any ideas?

      • BillNo Gravatar says:

        Sorry Brendan, there was an issue in the (lack of) files included with the library. Delete everything you downloaded, download the library and unzip it again, it should compile now.

        • Brendan WertanenNo Gravatar says:

          Thanks, that definitely got it to compile. I am still having an issue with it recognizing the SFMP3Shield.h whereas in your demo sketch it turns orange. Below where your libraries are included, the SdFat sd; SFMP3Shield MP3player are all still black.

          I placed the updated libraries into the correct folder as the directions specified. Am I making another mistake somewhere?

          • PacoNo Gravatar says:

            It was a big problem for me but you have to update the library sdfat, I did it and it worked instantly

    • Michael P. FlagaNo Gravatar says:

      If you are still having problem. Can you please move to the forum. http://www.billporter.info/forum/forum/sparkfun-mp3-shield-support-forum/. Please include your IDE’s results output. It will specify the exact error. As your description is confusing, in that you say it is compiling, but an orange line indicates a problem, with the compile.

    • EricNo Gravatar says:

      I believe I have the same problem as Brendan. I am using the basic code above. The code will compile but when it uploads to the board and I open the serial port it says the sd.begin wasn’t defined. I think it is because
      the libraries are not getting imported. The SPI is turning orange in the include statement but the SFEMP3Shield is not orange in the include statement.

      SPI is orange:
      #include

      Everything is black:
      #include
      #include
      #include

      This is all black as well:
      SdFat sd;
      SFEMP3Shield MP3player;

      Did I import something wrong or can you give me any suggestions as to what is happening?

      • Some GuyNo Gravatar says:

        If SdFat sd; and SFEMP3Shield MP3player; is not compiling it most likely (like 99% of the time) means that you messed up importing the library to your Arduino libraries file. The correct way is to first download the zip, when you download the zip file you can right click it and it should say Extract. (Again the zip file itself, not inside the zip file because downloading the file sometimes opens up the file with you in it already)

        Once you do that you want to move or copy all of the files and documents inside it into your Arduino library file which is probably on your c drive, on your c drive inside Program Files or on your c drive inside Program Files (x86). (Or where ever else you decide to put it when you first downloaded Arduino)

        There you will find your Arduino program file, inside it will be a file called libraries and inside there is where you want everything in the file extracted to go. Another thing is you might want to open the Arduino.exe file the Arduino file you are in, in case you have another version of Arduino or even the same version else where by accident.

        • EricNo Gravatar says:

          Thank you. Once I got the libraries installed it was the sd card not working correctly but it’s fixed now and it works!

    • […] contrôler le lecteur mp3: – La bibliothèque officielle mise à disposition par Sparkfun. – La bibliothèque de Bill Porter qui facilite grandement l’utilisation avec sa […]

    • ctb123No Gravatar says:

      Hi,
      I plan to use the Sparkfun MP3 player for an art installation where a pull cord attached to a switch activates different sounds. Is it possible to use your library to play sounds at random? And, to have the audio stop at the end of each track? Any assistance will be greatly appreciated. Thank you.

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