Carl DIY MP3 player for kids

Carl is a robust DIY MP3 player for kids. I already built Carl back in 2017, but it took until this summer that I also finished an article for the german edition of the Make magazine describing how to build Carl. The case is made of an old wooden box for wine bottles. The MP3 playback and amplification is handled by an DFPlayerMini module, the MP3 files are stored on a mini SD card. An Arduino Pro Mini controls everything. 12 buttons are connected through a single analog input to the Arduino. This simplifies wiring and keeps usage of GPIO low. The 9 small buttons are used to select a playlist, the big arcade buttons control playback and song selection. Carl is powered by an USB powerbank and can be easily recharged. While writing the firmware for Carl, both JLed and log4arduino originated as side projects.