The MH-M18 is a low-power Bluetooth design solution that supports Bluetooth 4.2 transmission, two-channel stereo lossless playback, and Bluetooth connection once the module is linked to Bluetooth, making it extremely easy. The Bluetooth connection distance in an open environment can be up to 20 meters. Bluetooth audio reception is widely utilized in a range of audio DIY projects.
Pins Functions Description
1 -KEY Button control terminal (4 button functions, additional resistors )
2 -MUTE Mute control terminal (output high-level 3.3V when muting, output low level during playback)
3 -VCC Positive power supply 5V (lithium battery 3.7V power supply requires short circuit diode)
4 -GND Power negative / audio signal ground
5 -L Left channel output
6 -R Right channel output Function
1 x Audio Bluetooth Module MH-M18 Wireless Receiver
1. This product outputs audio signals through Bluetooth. It must be connected to the power amplifier board to use it. It cannot directly drive the headphones.
2. The left and right channel audio signals are respectively connected to the left and right channels of the power amplifier board, and the ground signal of the audio is connected to the GND on the board. You can't connect the left and right channels together. If you only need mono, just connect the left channel or the right channel.
3. Noise or current sound occurs during playback. The power supply part is added to the LC filter circuit, or both ends of the power supply are connected with a large capacitor (at least 10uf, the bigger the better). It is recommended that the Bluetooth and the power amplifier board be powered separately to isolate the Bluetooth ground and the amplifier ground.
4. After the module is powered on, it cannot connect to Bluetooth. Please check if the power supply voltage is within the normal range or whether the power supply is stable. If the power supply is normal, the phone deletes the Bluetooth name and then searches again. Note that you can search for Bluetooth if the indicator light flashes quickly.
5, the module can not search for Bluetooth, or there is a stuck in the Bluetooth playback process. Please check if there are any wireless transmitting devices around you that are disturbed and away from these devices.
6. After the mobile phone is connected to Bluetooth, there is no sound or the speaker of the mobile phone makes a sound. Please re-power, and re-connect Bluetooth. Check if the media playback in the Bluetooth settings of the mobile phone is turned on.
After receiving the board, please power the module first to see if the indicator light flashes normally. After connecting it, please carefully check whether the wiring is correct and then supply power to prevent the wiring from damaging the module. Since this product is a bare board with components exposed on the board, be careful not to touch the components on the board during use. Especially when the weather is dry, touching the components by hand is easy to cause static electricity to damage the chip
Wiring the Audio Bluetooth Module Mh-m18 Wireless Board:
1. Power supply: The default is 5V. If you need to use a 3.7V lithium battery, you need to replace the diode (as shown) with a 0-ohm resistor of 0603, or directly short the two ends of the pad. If you use battery power, please pay attention to the battery to add a protective plate, there is low voltage protection to disconnect, otherwise it resistors such as wiring diagram)
2 MUTE A mute control terminal (output high-level 3.3V when muting, output low level during playback)
3 VCC Positive power supply 5V (lithium battery 3.7V power supply requires short circuit diode) 4 GND Power negative / audio signal ground 5 L Left channel output 6 R Right channel output will easily lead to battery discharge excessively burned the battery.
1. When there is noise during playback: The Bluetooth audio module consumes a lot of power, which has an impact on the audio quality. A linear controlled power supply is highly recommended. It is advised that you use an LC filter circuit if you are utilizing a DC-DC switching power source (such as a mobile phone charger).
2. Current sound: Caused by grounding interference, it is recommended that the output of the Bluetooth module should not be plugged in. It is necessary to weld the wire, especially the ground wire, and the wire should not be too long. The shorter the better, the thicker. The problem of audio grounding at the grounding point of the power amplifier board must be connected to the ground of the audio input of the power amplifier. This grounding point can be tried to solder at different positions to achieve the lowest current sound. It is recommended that the Bluetooth and the power amplifier board be powered separately to isolate the Bluetooth ground and the amplifier ground.
3. Signal interference: Bluetooth antennas are extremely susceptible to high frequency or strong electromagnetic signals, and should be placed away from places where wireless devices are sent. And the board can't be close to metal objects, keeping a certain distance. 4. MUTE mute port: When the module is muted, the port outputs a high level of 3.3V and outputs a low level of 0V during playback. If the power amplifier board mute high level is valid, it can be directly connected. If the power amplifier board mute is the low level control, you need to add the reverse circuit,
This is how you can make a DIY Bluetooth speaker with the Audio Bluetooth MH-M18 Module, as well as how to wire and connect it. In this video, the connections of the MH-M18 Module are extremely obvious, and it consists of one PAM8403 micro amplifier. Bluetooth module MH-M18 (two). 3- Micro USB lithium charger with 1 amp and 5 volts. Speaker with a 4-4 ohm impedance and a 3-watt output. Lithium battery with a capacity of 5 to 1000 mAh: