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BLK-MD-SPK-B Bluetooth module is designed for product design of Bluetooth speakers. Has the characteristics of high integration, small size, just with a few external components will be able to achieve its powerful features. With A2DP, AVRCP transmission and remote control protocol any Bluetooth audio device (such as: Bluetooth-enabled mobile phone, computer Bluetooth adapter, etc.) to establish a connection, to achieve high-quality stereo audio stream wireless receiver, and audio player remote control. BLK-MD-SPK-B Bluetooth stereo receiver module to the user interface, remote control buttons work the status indication interface, stereo audio output interface.



  • Class2 power level.
  • The built-in lithium battery charging circuit.
  • Powerful noise elimination circuit.
  • Effective transmission distance up to 20 meters.
  • Follow the Bluetooth V2.0 + EDR Bluetooth specification.
  • Support A2DP V1.2, AVRCP V1.4 profiles
  • Integrated EEPROM configurable operating modes and parameters
  • Stereo audio output can directly drive 40mW @ 32Ωspeeker without the need for DC-blocking capacitor
  • Integrated power-on reset and programmable low voltage monitoring function
  • 5 Control buttons, including the switch machine play pause button, volume plus the volume down on the one, the next one. Supports no button automatic connection function.
  • 2 LEDs used to indicate different working status

Application Ideas

  • All kinds of high-quality Bluetooth stereo audio receiving device.
  • All kinds of high-quality Bluetooth stereo speakers, audio.


  • Power supply decoupling capacitors should be located close to the module pins.
  • The module substrate should be fully Shop (antenna below can not shop), and in the position of the substrate covered with insulating white oil.
  • The audio circuit ground and other ground should be separated, sufficient grounding at the power ground separate alignment
  • Module ground should be separated from the other ground at full power ground traces alone in the ground.
  • All the ground should be a large number of shop copper, multi-punched.
  • The module antenna placed as far as possible the edge of the base plate, the antenna near metal objects can not have, to ensure good communication with the outside world.
  • Is preferably the antenna protruding floor, or to the floor below the antenna milling empty.


  • BT-Speaker of the module name
  • Module pairing code 0000
  • Baud Rate 115200
  • Module size: 14x23mm
  • Working pressure VBAT: 3.4 - 4.2V

Pin definition and Rating


No IO Define Input/Output Pin Function Description
1 GND Input/Output Ground
2 GND Input/Output Ground
3 SPKN Output Stereo differential output negative terminal
4 SPKlP Output Stereo left channel differential output positive terminal
5 SPKRP Output Stereo right channel differential output positive terminal
6 GND Input/Output Ground
7 MIC Input Microphone input
8 VMIC Output Microphone power
9 BLED Input The work status indications interface usually pick the blue lights
10 CHG Input Lithium battery charging input port
11 RLED Input State-of-charge, and pairing status indicator Interface usually pick a red light
12 VBAT Input Lithium battery positive terminal (power input)
13 GND Input/Output Ground
14 CHG Input/Output Ground
15 MFB Input Switch machine (L) / receive calls / playback pause (short press)
16 VOL+ Input The volume increased control interface
17 VOL- Input Reduce the volume control interface
18 RST Input Reset Interface
19 TXD Output Serial signal output
20 RXD Input Serial signal input
21 FWD Input Playing under a control interface
22 BACK Input Play on a control interface
23 MUTE Output Mute (no audio output, audio output)
24 1V8 Output 1.8V voltage output of
25 GND Input/Output Ground
26 GND Input/Output Ground

Reference connect circuit


Performance parameters


The projects and application examples.

Bill of Materials (BOM) /parts list

All the components used to produce the product.


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Version Tracker

Revision Descriptions Release
v1.0 Initial public release date

Bug Tracker

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Additional Idea

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See Also

Other related products and resources.


This documentation is licensed under the Creative Commons Attribution-ShareAlike License 3.0 Source code and libraries are

licensed under GPL/LGPL, see source code files for details.

External Links

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