Button control terminal (4 button functions, need to
add additional resistance
Mute control terminal (output high level 3.3V when
mute, output low level during playback)
Power supply positive pole 5V (short circuit diode
required for 3.7V power supply of lithium battery)
MUTE mute control terminal:
used to control the power amplifier board, MUTE output high level 3.3V when mute, output low level during
playback.
KEY button control:
This function can be realized only by connecting additional resistors and buttons.
Volume power-off retention function: The default output is 100% volume. The volume can be increased or
decreased by pressing the button. If the control volume is less than 15%, the volume output is 15% after re-
powering; if the control volume is greater than 15%, the original volume remains unchanged after re-powering.