Connecting LilyPadArduino 328 with MP3 trigger v2

Hi,

I need urgent help. I would like to connect the MP3 trigger v2 with the Lilypad Arduino. To establish a data connection, I connected the RX from the MP3 trigger to the TX of the Arduino. GND from MP3 Trigger I connected to the negative terminal of the Arduino. Both have power but I get no response with for example Serial.write (‘v’) and Serial.write (200). This shut do some volume changing Or is there instead of the serial connection an analog or digital connection? I’ve tried so much, but unfortunately still not been successful.

I hope someone can help.

Thanks in advance