Hi everyone, I want to code a programm that plays sounds with DFPlayer and a small speaker. First I found one sample code from the internet that I want to change. It works in the tutorial, but when I'm trying to upload it on my Arduino I get some errors: Arduino: 1.8.10 (Windows 8.1), Board: "Arduino Uno" C:\Users\User\Desktop\Joystick\DFPlayer-test\DFPlayer-test.ino: In function 'void setup()': DFPlayer-test:28:1: error: 'playFirst' was not declared in this scope playFirst(); ^~~~~~~~~ C:\Users\User\Desktop\Joystick\DFPlayer-test\DFPlayer-test.ino: In function 'void loop()': DFPlayer-test:40:7: error: 'pause' was not declared in this scope pause(); ^~~~~ DFPlayer-test:45:7: error: 'play' was not declared in this scope play(); ^~~~ C:\Users\User\Desktop\Joystick\DFPlayer-test\DFPlayer-test.ino:45:7: note: suggested alternative: 'delay' play(); ^~~~ delay DFPlayer-test:54:7: error: 'playNext' was not declared in this scope playNext(); ^~~~~~~~ DFPlayer-test:62:7: error: 'playPrevious' was not declared in this scope playPrevious(); ^~~~~~~~~~~~ C:\Users\User\Desktop\Joystick\DFPlayer-test\DFPlayer-test.ino:62:7: note: suggested alternative: 'buttonPrevious' playPrevious(); ^~~~~~~~~~~~ buttonPrevious Multiple libraries were found for "SoftwareSerial.h" Used: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.3\libraries\SoftwareSerial exit status 1 'playFirst' was not declared in this scope This report would have more information with "Show verbose output during compilation" option enabled in File -> Preferences. The code is: #include "SoftwareSerial.h" SoftwareSerial mySerial(10, 11); #define Start_Byte 0x7E #define Version_Byte 0xFF #define Command_Length 0x06 #define End_Byte 0xEF #define Acknowledge 0x00 #define ACTIVATED LOW int buttonNext = 2; int buttonPause = 3; int buttonPrevious = 4; boolean isPlaying = false; void setup () { pinMode(buttonPause, INPUT); digitalWrite(buttonPause,HIGH); pinMode(buttonNext, INPUT); digitalWrite(buttonNext,HIGH); pinMode(buttonPrevious, INPUT); digitalWrite(buttonPrevious,HIGH); mySerial.begin (9600); delay(1000); playFirst(); isPlaying = true; } void loop () { if (digitalRead(buttonPause) == ACTIVATED) { if(isPlaying) { pause(); isPlaying = false; }else { isPlaying = true; play(); } } if (digitalRead(buttonNext) == ACTIVATED) { if(isPlaying) { playNext(); } } if (digitalRead(buttonPrevious) == ACTIVATED) { if(isPlaying) { playPrevious(); } } } If you've got ideas how I can make this code work, I'll be thankful. Best regards Kris

You are missing a #include of some DFPlayer library which contains all the functions you are calling in your code. The multiple libraries for SoftwareSerial.h is not the problem.

[image] kristiyan_peshev: Multiple libraries were found for "SoftwareSerial.h" Used: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.3\libraries\Softw This specific "Multiple libraries were found for" message was the result of a bug: https://github.com/arduino/Arduino/issues/9601 It was fixed a couple of years ago, but you're using a super outdated version of the Arduino IDE. You'll know a legitimate "Multiple libraries were found for" message because it will list the paths of each of the multiple libraries. When you see only a single path, that message results from the bug.

I included "DFRobotDFPlayerMini.h" and defined RX and TX pins and now everything works normally. Thank you!

Excuse me! I'm new here, I didn't know that.

Multiple libaries were found for "SoftwareSerial.h"

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groundFungus August 17, 2021, 7:37pm 3

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Multiple libaries were found for "SoftwareSerial.h"

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