MH MX8 Module WirelessAudio Receiver Board Lossless Decoder Kit With M18 M28 M38, Volume Control, 5W+5W , USB Sound Card Support

M18: MUTE mute control terminal: used to control the power board. When muting, MUTE outputs a high of 3.3V, and outputs a low during playback. KEY button control: This function requires additional connection of resistors and buttons to achieve Volume power off function: The default output is volume. Press the button to control the volume increase and decrease. If the control volume is less than 15%, the volume output will be 15% after power-on; if the control volume is greater than 15%, the original volume will remain unchanged after power-on