It is a lossless MP3 player module and its main features are Micro SD / USB HD or key socket, onboard audio amplifier, power 3W under 4Ω @ VCC 5.0V (2W under 4Ω @ VCC 3.7V) will accept up to 5V, headphone 3.5mm jack socket, micro USB socket for power, screw embase for solderless speaker connection.

4 function keys : Play/Pause/Mode (MicroSD or USB), Previous/Volume–, Next/Volume++, Repeat/Normal. Acces to alternative function is done by holding the key for more 2 seconds.

By default this module will try to read from Micro SD, if no card is found then it will switch to USB automatically, of course it is also possible to select manually which slot to use, with the Play/Pause/Mode key (hold). This module can be possibly be controlled by a micro-controller or an AVR such as an Arduino board, an ATtiny or anything usually these SOC are using an ADC line along with a resistor value per function key, these could be replaced by a PWM line generating expected tensions directly.