Features Use: After the module is powered on, the mobile phone searches for the Bluetooth name MH‑M18 / MH‑M28 / MH‑M38, and connects to Bluetooth to play music. Applicable to: For Bluetooth V4.2, for Bluetooth automatic technology, support WAV/WMA/FLAC/APE/MP3 lossless decoding, stereo two-channel output. Power Supply: It can be directly powered by 5V MICRO USB Android cable, or it can be connected to 5V power supply or 3.7V lithium battery (as shown in the figure below). 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 headset can be directly connected to the 3.5mm audio interface, or it can be wired to the audio input of the power amplifier board (the interface L/R/AGND can be directly wired as shown in the figure). Widely Applicable: The lossless decoder DIY kit is widely used in various Bluetooth audio receivers, DIY conversion of various sounds, etc., which can meet your diverse needs. Specification: Item Type: ModuleFunction / modelM18M28M38MICRO MH-M18:NumberPinDescription1KEYButton control terminal (4 button functions, additional resistance required)2MUTEMute control terminal (output high level 3.3V when muting, output low level during playback)3VCCPositive power supply 5V (lithium battery 3.7V power supply requires short circuit diode)4GNDNegative power supply5LLeft channel output6RRight channel output MH-M28: NumberPinDescription15VPower positive 5V2GNDNegative power supply3VBATLithium battery positive 3.7-4.2V4LLeft channel output5RRight channel output6AGNDAudio ground MH-M38:NumberPinDescription15VPower positive 5V2GNDNegative power supply3VBATLithium battery positive 3.7-4.2V4L+/L-Left channel output (direct speaker)5R+/R-Right channel output (direct speaker) Blue Module: The light blinks when for Bluetooth is not connected The indicator light usually lights up when for Bluetooth is connected For Bluetooth appears during playback, slow flashing Package List: 1 x Module or 1 x Module2 x Female Connector2 x Male Connector Package List 1 x Module 2 x Female Connector 2 x Male Connector