compilation error on AI Thinker ESP32-CAM: undefined reference to `DY::Player::Player(int, unsigned char, unsigned char)'

[lionaid]

Hi there,

thank you very much for this great work of implementing the communication protocol.

I just tried to use your library with the AI Thinker ESP32-CAM board and the Espressif Arduino core for the ESP32 in the Arduino IDE 2.1.0 on macOS 12.3.1.

However, a minimal example (simplified from your esp32 example), using only the creation of a player variable with your DY::Player class (see below) already fails with this error message:

/Users/lion/Library/Arduino15/packages/esp32/tools/xtensa-esp32-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld: /private/var/folders/q1/jhtqw8ys3kdb_dn83_55fstr0000gn/T/arduino/sketches/0E70F041FA60B7BAC5DE78818341E610/sketch/DY_minimal_example.ino.cpp.o:(.literal.startup._GLOBAL__sub_I_player+0x0): undefined reference to `DY::Player::Player(int, unsigned char, unsigned char)'
/Users/lion/Library/Arduino15/packages/esp32/tools/xtensa-esp32-elf-gcc/esp-2021r2-patch5-8.4.0/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld: /private/var/folders/q1/jhtqw8ys3kdb_dn83_55fstr0000gn/T/arduino/sketches/0E70F041FA60B7BAC5DE78818341E610/sketch/DY_minimal_example.ino.cpp.o: in function `_GLOBAL__sub_I_player':
/Users/lion/Documents/Arduino/DY_minimal_example/DY_minimal_example.ino:7: undefined reference to `DY::Player::Player(int, unsigned char, unsigned char)'
collect2: error: ld returned 1 exit status

exit status 1

Compilation error: exit status 1

DY_minimal_example.ino

#include <DYPlayerESP32.h>

DY::Player player(UART_NUM_2, 12, 13);

void setup() {
  player.setVolume(15); // 50% Volume
}

void loop() {
  /* Nothing to do.. */
  delay(5000);
}

I would be super happy if you could give me any hints on what the problem might be.

Cheers! Lion

[alastaira]

I think the confusion comes from the fact that the "Arduino" and "ESP32" examples that come with the library don't refer to whether you're targetting Arduino or ESP32 hardware, but rather whether you're using the Arduino IDE or ESP-IDF development environments. If you're writing code for an ESP32 board but using the Arduino IDE, you'd still use the "DYPlayerArduino.h" library, as follows:

#include "DYPlayerArduino.h"
DY::Player player(&Serial2);

void setup() {
  // Protocol, Rx, Tx pins
  Serial2.begin(9600, SERIAL_8N1, 16, 17);
  player.playSpecified(1);
}

[lionaid]

oh great. I totally didn't get that 😃