NeedHelpUnderstandingError

Development Tools IDE 1.x
1

I'm using the code for the MP3 Shield music box. I worked out all the other errors. This is the code:
//SFEMP3Library author Bill Porter
//SFEMP3Library author Michael P. Flaga
/* MP3 Player Shield Music Box Code Example:
SparkFun Electronics, Pamela, 1/24/2013
Beerware License

Hardware Connections:
-LED = D3 on MP3 Player Shield;
-Motor = D5 on MP3 Player Shield;
-Reed Switch = D4 on MP3 Player Shield;
-Mono Audio Amp Breakout Board Shutdown Pin = D10 on MP3 Player Shield;
You will need to solder header pins to the MP3 Player Shield.
Put the shield on top of an Arduino Uno.

Usage:
When the door opens, the motor will spin and a sound file will play.
The sound file will loop.
Then when the door closes the motor stops spinning and a new track plays one time. */

#include <SPI.h>

//Add the SdFat Libraries
#include <SdFat.h>

//and the MP3 Shield Library
#include <SFEMP3Shield.h>

SFEMP3Shield MP3player;

int led = 3;
int motor = 5;
int reedSwitch = 4;
int speaker = 10;

int fadeAmount = 5;
int brightness = 0;
boolean active = false;

void setup() {
pinMode(motor, OUTPUT); //Motor
pinMode(led, OUTPUT); // LED
pinMode(reedSwitch, INPUT); //Reed Switch
pinMode(speaker, OUTPUT); //Speaker Enable

analogWrite(led, 0); //LED off
digitalWrite(reedSwitch, HIGH); //turn on internal pullups for reed input
digitalWrite(motor, LOW); //Motor off

MP3player.begin();
MP3player.setVolume(0x00, 0x00); //set volume
}

void loop() {

if (digitalRead(reedSwitch) == HIGH && !active)//when door opens
{
active = true;
analogWrite(led, 80);
digitalWrite(speaker, HIGH);
digitalWrite(motor, HIGH);
MP3player.stopTrack();
MP3player.playTrack(3);
}
else if (digitalRead(reedSwitch) == LOW && active)//when door closing
{
active = false;
MP3player.stopTrack();
MP3player.playTrack(2);
digitalWrite(motor, LOW);
analogWrite(led, 255);
}
else if (digitalRead(reedSwitch) == LOW) //while door is closed
{
analogWrite(led, 0);
digitalWrite(motor, LOW);
}
else
{
MP3player.playTrack(1);
analogWrite(led, brightness);
if (brightness == 0 || brightness == 255) {
fadeAmount = -fadeAmount;
}
brightness += fadeAmount;
}

delay(100);
}

I can't figure out what this error means:
Arduino: 1.8.9 (Windows Store 1.8.21.0) (Windows 10), Board: "Arduino Uno"

C:\Users\EMELIO FAMILY\Documents\Arduino\libraries\SFEMP3Shield\SFEMP3Shield.cpp: In member function 'uint8_t SFEMP3Shield::vs_init()':

C:\Users\EMELIO FAMILY\Documents\Arduino\libraries\SFEMP3Shield\SFEMP3Shield.cpp:292:34: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]

if(VSLoadUserCode("patches.053")) return 6;

^

C:\Users\EMELIO~1\AppData\Local\Temp\ccOiK9DN.ltrans0.ltrans.o: In function `begin':

C:\Users\EMELIO FAMILY\Documents\Arduino\libraries\SFEMP3Shield/SFEMP3Shield.cpp:141: undefined reference to `sd'

collect2.exe: error: ld returned 1 exit status

exit status 1
Error compiling for board Arduino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

2

Please post a link (using the chain links icon on the forum toolbar to make it clickable) to where you downloaded the SFEMP3Shield library from. Or if you installed it using Library Manger (Sketch > Include Library > Manage Libraries in the Arduino IDE or Libraries > Library Manager in the Arduino Web Editor) then say so and state the full name of the library.

3

This is where I got the library:

4

To fix the error, add the following code to your sketch anywhere after the #include directive for SdFat.h:

SdFat sd;

Since you're using a pre-written sketch, it does make sense to use that SFEMP3Shield library. However, if you are going to write your own code for that MP3 shield, you should note what it says in the SFEMP3Shield library's readme:

This project and support has been migrated to Arduino_Library-vs1053_for_SdFat, where "VS1053 for use wiht SdFat" is availabe directly from the Arduino IDE Library manager for download.

This instance of the project is effectively closed, please submit all issues and pull requests to Arduino_Library-vs1053_for_SdFat

There may have been new improvements made to that "VS1053 for use with SdFat" library, whereas continued development of the SFEMP3Shield library has been abandoned.