An Arduino-based device that can play MP3 files from a microSD card.

• Play MP3 files from microSD card.
• Go to next and previous songs with single press.
• Increase and decrease volume level with long press.
• Pause and resume the currently played song with double press.
• LED that indicates when a song is played.

• 1x Arduino Nano
• 1x DFRobot's DFPlayer Mini board
• 1x 8Ω 0.5W speaker - according to the specs DFPlayer can direct drive a 4/8Ω 3W speaker
• 3x button
• 1x 220Ω resistor
• 1x 1kΩ resistor - required because the Arduino is 5V, but the DFPlayer is 3.3V
• 1x microSD card - maximum 32GB formatted to FAT32
• 1x LED
• wires

DFPlayer has a serial protocol, so we are using the Arduino SoftwareSerial library to use pin 11 and 10 as TX and RX ports. The low level protocol is documented in the module's datasheet.

Although there are newer libraries (like DFPlayerMini_Fast) I used DFRobot's DFRobotDFPlayerMini library to wrap the low level serial details. The best documentation of this library is the FullFunction example.

Section 1.4 in the datasheet describes how the files should be named on the SD card. Basically you have to create an mp3 folder in the root and name your files 0001.mp3, 0002.mp3 and so on.

Important! The order of the files is not determined by their name, but by the order they are written to the SD card! The best approach is to name the files on your computer and then copy them to the SD card.

The SD card must be formatted to FAT32 and in my experience it must have only a single partition.

I downloaded several files from https://www.101soundboards.com and they all worked with DFPlayer.

According to the documentation the IO1 and IO2 pins can be used to control volume level and to navigate between the songs.

Short press means playing the next and previous songs, long press means increasing and decreasing the volume level.

In my experience the documentation is not correct: IO2 has the Next/Vol+ functionality and IO1 has Pre/Vol-.

Although the ADKEY pins could be used to add more buttons, I decided to control play/pause from software, so I connected a button to the Arduino and used Matthias Hertel's OneButton library so I didn't have to deal with debouncing the button and I could easily add support for double press.

DFPlayer's BUSY pin goes LOW when a song is being played and goes HIGH when the device is in idle state, so I added a LED that works in sync with the onboard LED.

From code the player.available() function behaves similarly.

This project was created by György Balássy.