Features
- Bluetooth version: 4.2
- Supports lossless formats: WAV / WMA / FLAC / APE / MP3
- Stereo dual-channel output
- Bluetooth name: MH-M18
- Indicator light behavior:
- Flashes quickly when not connected
- Constant when connected
- Flashes slowly during playback
Pin Functions
| Pin |
Label |
Description |
| 1 |
KEY |
Button control terminal (requires extra resistors) |
| 2 |
MUTE |
Mute control output:
High = 3.3V (muted), Low = 0V (playback) |
| 3 |
VCC |
Power supply 5V (use 0-ohm resistor or short pad for 3.7V battery) |
| 4 |
GND |
Power and audio ground |
| 5 |
L |
Left channel output |
| 6 |
R |
Right channel output |
Audio Wiring Instructions
- Connect L, R, and GND to the power amplifier board’s input.
- Do not connect L and R together for mono. Use only one channel if mono is needed.
- Does not support direct headphone connection. Use an amplifier board.
Power Supply Notes
- Default: 5V power via VCC and GND
- For 3.7V lithium battery use:
- Connect to VBAT and GND
- Replace diode with a 0603 0-ohm resistor or short the pad directly
- Use a lithium battery with a protection circuit
Noise & Interference Troubleshooting
- Noise during playback: Use a linear power supply or LC filter if using a switching power source.
- Current sound:
- Avoid plug-in wires at output, especially for GND.
- Use thick, short, and soldered wires for GND.
- Bluetooth and amplifier should be powered separately.
- Signal interference: Keep Bluetooth module away from high-frequency devices and metal objects.
Common Issues
- No sound after connection: Check Bluetooth media settings and reconnect.
- Not discoverable: Ensure indicator is flashing. Reboot and retry pairing.
- Playback stuttering: Remove nearby wireless transmitters that may interfere.
- Mute signal logic: If amplifier mute uses low-level, add an inverter circuit.
Precautions
- Power the module before wiring to check the indicator.
- Double-check all wiring before applying full power.
- Handle carefully — exposed components are vulnerable to static discharge damage.
DIY Bluetooth Speaker Sample Setup
Use the MH-M18 with a PAM8403 amplifier module, 3.7V lithium battery (with protection), micro USB charger, and a 4Ω 3W speaker to build a custom Bluetooth speaker.
Features
- Bluetooth version: 4.2
- Supports lossless formats: WAV / WMA / FLAC / APE / MP3
- Stereo dual-channel output
- Bluetooth name: MH-M18
- Indicator light behavior:
- Flashes quickly when not connected
- Constant when connected
- Flashes slowly during playback
Pin Functions
| Pin |
Label |
Description |
| 1 |
KEY |
Button control terminal (requires extra resistors) |
| 2 |
MUTE |
Mute control output:
High = 3.3V (muted), Low = 0V (playback) |
| 3 |
VCC |
Power supply 5V (use 0-ohm resistor or short pad for 3.7V battery) |
| 4 |
GND |
Power and audio ground |
| 5 |
L |
Left channel output |
| 6 |
R |
Right channel output |
Audio Wiring Instructions
- Connect L, R, and GND to the power amplifier board’s input.
- Do not connect L and R together for mono. Use only one channel if mono is needed.
- Does not support direct headphone connection. Use an amplifier board.
Power Supply Notes
- Default: 5V power via VCC and GND
- For 3.7V lithium battery use:
- Connect to VBAT and GND
- Replace diode with a 0603 0-ohm resistor or short the pad directly
- Use a lithium battery with a protection circuit
Noise & Interference Troubleshooting
- Noise during playback: Use a linear power supply or LC filter if using a switching power source.
- Current sound:
- Avoid plug-in wires at output, especially for GND.
- Use thick, short, and soldered wires for GND.
- Bluetooth and amplifier should be powered separately.
- Signal interference: Keep Bluetooth module away from high-frequency devices and metal objects.
Common Issues
- No sound after connection: Check Bluetooth media settings and reconnect.
- Not discoverable: Ensure indicator is flashing. Reboot and retry pairing.
- Playback stuttering: Remove nearby wireless transmitters that may interfere.
- Mute signal logic: If amplifier mute uses low-level, add an inverter circuit.
Precautions
- Power the module before wiring to check the indicator.
- Double-check all wiring before applying full power.
- Handle carefully — exposed components are vulnerable to static discharge damage.
DIY Bluetooth Speaker Sample Setup
Use the MH-M18 with a PAM8403 amplifier module, 3.7V lithium battery (with protection), micro USB charger, and a 4Ω 3W speaker to build a custom Bluetooth speaker.
