5V: Power positive 5V
GND: Negative power supply
VBAT: Lithium battery positive 3.7-4.2V
L: Left channel output
R: Right channel output
AGND: audio ground
Power supply: It can be directly powered by the MICRO USB Android cable 5V, or it can be connected to a 5V power supply or a 3.7V lithium battery. Note that the 5V and 3.7V power supply interfaces are different. The 5V voltage is connected to 5V and GND, and the 3.7V lithium battery is connected to VBAT and GND.
Audio output: The earphone can be directly connected to the 3.5mm audio interface, or it can be wired for the audio input of the power amplifier board (interface L/R/AGND can be directly wired).