1. Introduction
The EGBO KCX_BT_EMITTER module is a versatile wireless Bluetooth audio transceiver module, integrating both Bluetooth stereo audio transmission and reception capabilities. Utilizing Bluetooth 5.3 protocol, it supports automatic connection to previously paired Bluetooth devices. This module can be configured for either transmitting or receiving audio signals via a simple solder joint setting. It also features an indicator light for status display and connection status level output, making it suitable for various applications including Bluetooth audio reception, transmission, wireless audio transmission, and DIY audio projects.
The module supports serial port AT commands for advanced configuration, allowing users to manage device name connections, search results, modify Bluetooth names, and control connection/disconnection.
Video: Overview of the EGBO KCX_BT_EMITTER Bluetooth module.
2. Specifications
Below are the technical specifications for the KCX_BT_EMITTER module:
| Feature | Specification |
|---|---|
| Product Model | KCX_BT_EMITTER |
| Bluetooth Version | 5.3 |
| Bluetooth Name | Bluetooth Audio |
| Operating Voltage | 3.5V - 5V DC |
| Working Current | 35mA |
| Launch Distance (no occlusion) | < 20 meters |
| RF Output Power | +5dBm |
| RF Frequency Range | 2402-2480MHz |
| Audio Dynamic Range | 80dB |
| Total Harmonic Distortion (Audio) | -70dB |
| Sound Frequency Response | 20Hz - 20KHz |
| Audio Signal-to-Noise Ratio | 95dB |
| Audio Input/Output Signal Amplitude | ≤ 2Vpp |
| Number of Channels | 2 channels (stereo) |
| Transmission Delay | 250-300mS |
| Package Type | SMD |
| Operating Temperature | -40°C ~ 80°C |
| Dimensions (L x W) | 23mm x 15mm |
| Weight | 0.91g |
Image: Module overview highlighting key features and specifications.
Image: Module dimensions (23mm x 15mm) and weight (0.91g).
3. Setup and Installation
3.1. Pinout Description
The module features 11 pins for various connections. Refer to the table and diagram below for detailed pin descriptions:
| Serial No. | Name | Description of Function |
|---|---|---|
| 1 | +5V | 3.5-5V power supply pin |
| 2 | PGND | Power supply ground |
| 3 | LINK | Connected status foot; Bluetooth has connection output 3.3V, no connection output 0V |
| 4 | RX | Serial port receiver (extended function pin, used for serial port configuration Bluetooth related information) |
| 5 | TX | Serial port transmitter (extended function pin, used for serial port configuration Bluetooth related information) |
| 6 | AUDIO_L | Audio signal Left audio channel input/output dual function port (configured in transmit mode input audio signal, configured in receive mode output audio signal) |
| 7 | AUDIO_R | Audio signal Right audio channel input/output dual function port (input audio signal when configured in transmit mode, output audio signal when configured in receive mode) |
| 8 | AGND | Audio frequency ground |
| 9 | DP | USBDP data cable interface (used to connect the computer USB as a sound card) |
| 10 | DM | USBDM data cable interface (used to connect the computer USB as a sound card) |
| 11 | CONNECT | External connection pairing button port (same as module connection pairing button function) |
Image: Top view of the module with pin labels and component callouts.
Image: Bottom view of the module showing pin labels.
3.2. Mode Selection (Transmit/Receive)
The module's operating mode (transmitting or receiving) is determined by the RX/TX solder joint. The factory default setting is transmitting mode (solder joint not connected).
- Transmit Mode: The RX/TX solder joint is not connected. In this mode, the AUDIO_L/AUDIO_R pins act as audio inputs.
- Receive Mode: The RX/TX solder joint is connected (welded). In this mode, the AUDIO_L/AUDIO_R pins act as audio outputs.
Image: Illustration of the TX/RX solder joint for setting transmit or receive mode.
3.3. Wiring Diagrams and Application Scenarios
Proper wiring is crucial for optimal performance and to avoid noise. Always ensure the power supply voltage is within 3.5-5V.
3.3.1. Power Supply Connection
Connect the +5V pin to the positive terminal of your 3.5-5V power supply and the PGND pin to the power supply ground. An external 10V/100uF electrolytic capacitor (C1) must be connected between +5V and PGND, placed as close as possible to the module's power pins for effective filtering.
Image: Recommended power supply wiring diagram.
For battery-powered applications, ensure the AGND (audio ground) is connected by an independent wire to the negative electrode of the battery or the main filter capacitor of the power supply to minimize noise.
Image: Example wiring with a battery and 3.5mm audio cable.
3.3.2. Audio Connection (Method 1: Analog Audio)
This method is suitable for both transmitting and receiving modes using analog audio signals.
- Transmit Mode: Input analog audio signals (e.g., from a phone, computer, MP3/MP4 player) to the IN_L and IN_R pins.
- Receive Mode: The module outputs analog audio signals from the IN_L and IN_R pins, which can be connected to headphones or an audio amplifier.
Image: Application scenario showing module used for transmitting and receiving audio with various devices.
3.3.3. Audio Connection (Method 2: USB Audio - Transmit Mode Only)
This connection method is applicable only in transmit mode. Connect the module to a computer via the USB communication interface (DP and DM pins). Once the transmission module and a receiving Bluetooth module are successfully connected, the computer system will recognize the module as a "USBAudio2.0" sound card device. The audio signal played on the computer will then be converted by the transmitting module into a Bluetooth signal and transmitted wirelessly to the Bluetooth receiving module.
Image: Wiring diagram for USB audio connection in transmit mode.
3.4. External Antenna
The module includes an IPX1 external 2.4G antenna interface. If the product is housed in a metal enclosure, an external antenna is required as 2.4G Bluetooth signals cannot pass through metal. When designing your PCB, ensure the module's PCB antenna area is not covered by copper foil or other metal to maintain communication distance.
Image: Bluetooth 5.3 module shown with an external antenna.
4. Operation
4.1. Pairing and Connection
The module features a dedicated pairing button (also accessible via the CONNECT pin) for controlling Bluetooth connections.
- Short Press: Disconnects the current Bluetooth connection and initiates pairing mode to connect to a new device.
- Long Press (2 seconds): Switches between line audio input and USB audio input. USB audio input is only valid when connected to a computer.
4.2. Status Indicator
A red and blue dual-color LED light is integrated on the module to indicate its status:
4.2.1. Transmit Mode (Red Light Effective)
- Bluetooth Not Connected: Red light flashes evenly.
- Bluetooth Connected: Red light flashes twice with an interval of 5 seconds.
4.2.2. Receive Mode (Blue Light Effective)
- Bluetooth Not Connected: Blue light flashes evenly.
- Bluetooth Connected: Blue light flashes twice with an interval of 5 seconds.
Image: Diagram detailing key button functions and LED indicator behavior.
5. Maintenance
To ensure the longevity and optimal performance of your EGBO KCX_BT_EMITTER module, follow these general maintenance guidelines:
- Keep the module clean and free from dust and debris.
- Avoid exposing the module to extreme temperatures or humidity.
- Handle the module with care to prevent physical damage to components or solder joints.
- Ensure proper ventilation if integrating into an enclosure to prevent overheating.
6. Troubleshooting
6.1. Noise Issues (Current Sound)
If you experience noise or current sound, consider the following:
- Power Supply Voltage: Ensure the power supply voltage is strictly within the 3.5V-5V range. Voltages outside this range can damage the module or cause noise.
- AGND Connection: The AGND (audio ground) pin (Pin 8) must be connected by an independent wire to the negative electrode of the power supply (e.g., battery negative, or the negative output of a 5V regulated power supply). This provides a stable reference for the analog audio circuit and reduces common ground noise. Incorrect or absent AGND connection will result in significant noise and distortion.
- Filter Capacitor (C1): The 10V/100uF filter capacitor (C1) at the power end of the module is essential for filtering the power supply. It must be connected and placed as close as possible to the +5V and PGND pins. Do not omit this capacitor.
- Power Supply Quality: Ensure your power supply has minimal ripple. Noisy power supplies (e.g., some mobile phone chargers or power banks) can introduce noise into the audio signal.
- Wiring Accuracy: Most noise issues are caused by incorrect wiring or component parameter changes. Always follow the reference circuit diagrams and instructions precisely.
6.2. Signal Range and Penetration
- Range (No Obstacles): In an open environment without obstacles, the Bluetooth signal can typically transmit about 15-20 meters.
- Range (With Obstacles): Obstacles significantly reduce range. Within a 10-meter area, it generally works through 1-2 ordinary non-load-bearing walls. However, steel mesh or metal structures will block the signal.
- Metal Enclosures: 2.4G Bluetooth signals cannot pass through metal. If the module is used in a metal enclosure, an external antenna connected to the IPX1 interface is required.
- PCB Antenna Design: When integrating the module into a product PCB, do not place copper foil or other conductive material directly below the module's onboard PCB antenna, as this will impede signal transmission and reduce communication distance.
6.3. Compatibility and Usage Limitations
- Microphone Functionality: This module does not support microphone signal input and cannot be used as a wireless microphone. The 250-300ms transmission delay also makes it unsuitable for real-time microphone applications.
- Instrument Audio Transmission: Due to the 250-300ms transmission delay, this module is not suitable for applications requiring high real-time performance, such as instrument audio transmission.
- One-to-Many Connection: The Bluetooth audio standard typically supports only one-to-one connections. This module is designed for one-to-one use. For one-to-many applications, consider specialized 2.4G wireless audio series products.
- Bluetooth Receiver Compatibility (Transmit Mode): When configured for Bluetooth transmission, the module guarantees compatibility primarily with other modules of the same model for receiving. Compatibility with Bluetooth receivers from other manufacturers is not guaranteed due to varying internal resources and system support.
- Bluetooth Transmitter Compatibility (Receive Mode): When configured for Bluetooth reception, the module is generally compatible with all standard smartphones on the market.
- Interference: Bluetooth operates in the 2.4G band. It is recommended to avoid placing the module too close to wireless routers or other 2.4G devices to prevent channel preemption and maintain connection stability.
7. User Tips
- Noise Reduction is Key: Pay close attention to the power supply and grounding. An independent wire for AGND and the correct filter capacitor (C1) placement are critical for clear audio.
- Antenna Placement Matters: For best range, especially in enclosed spaces, ensure the antenna has a clear path and is not obstructed by metal. Use an external antenna if the module is inside a metal casing.
- Understand Delay: Be aware of the 250-300ms transmission delay. This module is excellent for general audio streaming but not for real-time applications like live microphone input or musical instruments.
- One-to-One Connection: Remember that this module is designed for one-to-one Bluetooth audio connections.
8. Warranty and Support
For technical support, troubleshooting assistance, or warranty inquiries, please contact the seller or manufacturer directly. Keep your purchase records for reference.
