1. Power supply: You can directly use the MICRO USB Android cable 5V for power supply, or you can
also connect 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.
2. 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 (the interface L / R / AGND can be directly wired).