Product description:

&This productMH-M18/M28/M38Design for Low Power Bluetooth Support for Latest Bluetooth4.2Transmission, dual-channel stereo sound lossless play, module connected to Bluetooth, can quickly achieve Bluetooth wireless transmission, very convenient. In open space, Bluetooth connection distance is up to20Rice.

Widely used in all kinds of Bluetooth audio reception, all kinds of audioDIY.

 

For different needs of customers, we provide3Versions for you to choose from:

 

Function description:

1. Bluetooth V4.2 version, which supports Bluetooth automatic loopback technology, WAV/WMA/FLAC/APE/MP3 lossless decoding and stereo two-channel output.
2. After the module is powered on, the mobile phone searches for the Bluetooth name mh-m18 / mh-m28 / mh-m38. After connecting to Bluetooth, music can be played;
3. Module blue indicator:

When Bluetooth is not connected, the LIGHT flashes;

When bluetooth is connected, the light is always on;

When Bluetooth is playing, the indicator light flashes slowly.

 

The following is a description of each release:

MH-M18:

Module interface using half-hole process, customers can directly patch or welding on the board.

 

 

Numbe	Pin	explain
1	KEY	Key control terminal (4 key functions, additional resistance required
2	MUTE	Mute control terminal (output high level 3.3V when mute, output low level when playing)
3	VCC	Power positive 5V (short circuit diode is required for 3.7V power supply of lithium battery)
4	GND	Negative power supply
5	L	Left channel output
6	R	Right channel output

 

 

 

 

MUTE mute control end: used to control the amplifier board, MUTE output high 3.3V when muted, low output when playing.

KEY key control: This function requires additional connection resistors and keys to be implemented.

Volume power off and hold function: output 100% volume by default. Press the key to control the volume to increase or decrease. If the volume is less than 15%, the volume output will be 15% after power on again; if the control volume is greater than 15%, the original volume will remain unchanged after power on again.

 

MH-M28:

 

Numbe	Pins	explain
1	5V	Positive pole of power supply 5V
2	GND	The power supply is negative
3	VBAT	Lithium battery cathode 3.7-4.2v
4	L	Left channel output
5	R	Right channel output
6	AGND	Audio ground

1. Power supply: you can directly use the 5V micro USB Android cable for power supply, or you can also access the & nbsp; & nbsp; & nbsp; & nbsp; 5V power supply or 3.7V lithium battery. Note that the power supply interfaces of 5V and 3.7V are different. 5V power is crimped to 5V and GND, and 3.7V lithium battery is connected to Vbat and GND.

2. Audio output: The headset can be directly connected to the 3.5mm audio interface, or can be wired for the audio input of the amplifier board (interface L/R/AGND).Can be wired directly).

 

 

MH-M38:

 

 

Numbe	Pin	explain
1	5V	+5V
2	GND	Negative pole of power supply
3	VBAT	Lithium battery cathode 3.7-4.2v
4	L+/L-	Left channel output (directly connected to horn)
5	R+/R-	Right channel output (directly connected to horn)

1. power supply: the MICRO USB Android line 5V can be directly used for power supply, or it can be connected to 5V power supply or 3.7V lithium battery. Pay attention to the different power supply interfaces between 5V and 3.7V. 5V is connected to 5V and GND, and 3.7v lithium battery is connected to VBAT and GND.

The maximum working current is 5V2A, which is recommended to be powered by a 5V2A regulatory power supply for better sound quality.

2. Support USB sound card, drive free (plug and play). Connect the module with the computer with USB data cable, and the computer can play music and output through the module power amplifier

3. audio output: output left and right channel stereo audio signal, can be connected to two 2-8 Euro 3-5 W horn, push memory & nbsp; 4 Euro 5 W horn.

 

4. copyProductionProduct has its own dual 5W amplifier circuit,Must not be used separately! The output of the two power amplifiers can not be connected in parallel or connected to the negative electrode, otherwise the power amplifier chip can be damaged.

 

• matters needing attention

1. Signal interference: Bluetooth antenna is extremely vulnerable to high frequency or strong electromagnetic signal interference, so it should be placed far away from the place where wireless equipment is sent. And the board can not be close to the metal objects, maintain a certain distance.

 

1. If the amplifier plate has an electrical sound, causing ground interference, it is recommended that the Bluetooth module output do not use plug-in,Necessary welding wire, especially ground wire to weld, and the line can not be too long, the shorter the better, as far as possible thicker. The problem of audio ground at the amplifier board grounding point must be connected to the ground at the amplifier audio input, which can be attempted to weld at different locations to achieve the lowest current sound.It is suggested that Bluetooth and power amplifier board should be powered separately, and Bluetooth ground and power amplifier should be isolated.

 

1. Because this product is designed for bare plate, try not to touch the components on the board with your hands, easy to lead to electrostectonic killing chip lead to burning.

 

Warning: The charging interface of this product is a current-limiting charging mode without charging management! For the safety of your life and property, please use lithium batteries with protective plates produced by regular manufacturers, and our company will not bear any responsibility for losses caused by improper use!

Also: There are two points to note when using MH-M18:

Power supply: 5V power supply is used by default. If you need to use a 3.7V lithium battery for power supply, you need to replace the diode with a 0 ohm resistor of 0603, or directly short circuit both ends of the pad.

 

The Bluetooth audio module requires very high power supply, which will affect the audio quality. It is suggested to add LC filter circuit, especially switching power supply (such as mobile phone charger, etc.).

 

 

Mute port: This module outputs high level 3.3V when mute and 0V when playing. Power amplifier board mute high level is effective, it can be directly connected. If the power amplifier board mute is low level control, need to add the reverse circuit