Ebyte Bluetooth Audio Module Product Line and FAQ

Product Line of Ebyte Bluetooth Audio Modules

According to the official documentation of Chengdu Ebyte Electronic Technology Co., Ltd., its Bluetooth audio modules are mainly divided into the following series based on main control chips, protocol versions, and functional features:

1. High-Performance, Programmable Audio Series (Based on Qualcomm Solutions)

This series focuses on high-quality audio and rich functions, supporting Active Noise Cancellation (ANC) and high-definition audio coding (such as aptX HD). It is suitable for high-end headphones, speakers, and gaming devices, mainly targeting secondary development.

Core Features of the Series:

• Development Threshold: Requires secondary development based on Qualcomm ADK (Audio Development Kit), with a relatively high technical threshold.

• Quick Usage: Can be paired with official test boards (such as EWT104-BT5125) for function verification.

• Key Hardware Design: The SYS_CTRL pin cannot be directly pulled up to VBAT; a recommended power-on delay circuit must be used. Audio input/output are differential signals, and the design must strictly refer to the recommended circuit.

2. Classic Driver-Free Audio Series (Based on CSR Solutions)

This series focuses on "driver-free" and plug-and-play functionality. Users can achieve high-quality audio transmission without complex Bluetooth protocol development. It has high integration and is suitable for rapid productization.

Core Features of the Series:

• Easy Development: Users only need to connect the module to the product power supply and audio lines to implement Bluetooth audio functions, greatly shortening the development cycle.

• Cost Advantage: Generally more cost-effective compared to programmable Qualcomm solutions.

• Key Hardware Design: The VREGENABLE (MFB) pin cannot be directly pulled up to VBAT; a delay circuit is also required. The audio circuit uses a differential design.

3. Audio + Data Dual-Mode Series

This series of modules can simultaneously perform Bluetooth audio transmission and BLE data transparent transmission, meeting the needs of smart devices for two-way data communication while playing audio.

Core Features of the Series:

• Function Integration: One module solves two needs: audio and control/data transmission, simplifying smart hardware design.

• Flexibility: Parameters can be configured via AT commands, combining ease of use with certain customization capabilities.

4. Extended Audio Applications of Transparent Transmission Modules

It is worth noting that many of Ebyte's BLE transparent transmission modules (such as E104-BT5032A, E104-BT53 series), although mainly designed for data transmission, their chips also support audio interfaces such as I2S. Users with strong development capabilities can implement simple audio transmission or voice functions on their own based on the secondary development platforms of these modules (such as nRF52 SDK). However, this does not fall into the category of "ready-to-use" audio modules.

General FAQ for Bluetooth Audio Modules

Integrating the "Frequently Asked Questions" and "Hardware Design Requirements" sections of various product specifications, the following are common problems and solutions encountered in the development and application of audio modules.

1. Power Supply and Reliability Issues (Most Core!)

Q: The module is easily damaged. What are the reasons? How to prevent it?
A: The vast majority of hardware damage stems from improper power supply handling. Please strictly abide by the following items:

• Voltage Must Not Exceed Limits:

• For EWM104-BT5125: The charging voltage VCHG must not exceed 6.5V, and the battery voltage VBAT must not exceed 4.6V, otherwise the module will be permanently burned out.

• For E104-BT30: The operating voltage range is 1.8V - 3.6V, with a recommended voltage of 3.3V. Exceeding the maximum value will damage the module.

• Be sure to carefully read the "Electrical Parameters" table in the corresponding model's specification sheet.

• Power Polarity Must Not Be Reversed: Be sure to confirm the correct positive and negative poles when connecting the power supply. Reversing the polarity will cause permanent damage to the module.

• Power Supply Quality and Margin: It is recommended to use USB or high-quality batteries for power supply, and the power supply ripple should be small. When designing the power supply circuit, reserve more than 30% power margin to ensure long-term stable operation.

• Power-On/Off Sequence (For Qualcomm/CSR Audio Modules):

• The SYS_CTRL pin of EWM104-BT5125/3040.

• The VREGENABLE (MFB) pin of E104-BT30.

• None of the above pins can be simply connected to VBAT through a pull-up resistor. The chip can only be pulled high to power on after the initialization is completed upon power-on. The official recommended power-on delay circuit (usually including transistors, capacitors, etc.) must be used, as a simple RC delay is unstable.

2. Audio Quality Issues

Q: There is noise, distortion, or low volume in the audio output?
A: Troubleshoot the following aspects:

• Differential Circuit Design: Audio outputs (such as SPK_L/N, SPK_R/N) and microphone inputs (such as MIC_P/N) are all differential signal pairs. When routing the PCB, the differential pairs must be routed in parallel with equal length, and shielding must be done well. Be sure to refer to the official hardware design circuit.

• Power Amplifier Matching: Confirm that the input impedance of the post-stage power amplifier circuit matches, and whether the driving capability (such as ohm number) matches the speaker.

• Power Supply Interference: Poor-quality or high-ripple power supplies will introduce noise. Ensure that the power supply for the audio part is clean, and it can be isolated from the digital power supply.

• Grounding: The module must be reliably grounded. It is recommended to use star single-point grounding to avoid noise introduced by ground loops.

3. Transmission Range and Connection Stability Issues

Q: The Bluetooth audio connection range is short and prone to disconnection?
A: This problem is strongly related to RF performance and the environment:

• Antenna and Environment (Common Fatal Issues):

• Never place the antenna inside a metal casing! Metal will greatly shield the signal, resulting in extremely short range.

• The antenna (whether it is a PCB antenna or an external antenna) should be exposed as much as possible and kept vertically upward.

• Avoid testing in harsh environments such as wall corners, ground, and seaside (seawater absorbs radio waves).

• Interference: 2.4GHz devices such as Wi-Fi routers and microwave ovens will cause co-channel interference. Try to stay away from them or change the module channel (if supported).

• Power Supply Voltage: A supply voltage lower than the recommended value will result in insufficient transmit power, shortening the range.

4. PCB Hardware Design Issues

Q: How to design the PCB to ensure the best performance of the module?
A: RF and audio modules are extremely sensitive to PCB layout:

• No Routing Under the Module: High-frequency digital lines (such as USB), high-frequency analog lines, and power lines must avoid the area directly below the module.

• Routing Handling When Unavoidable: If routing must pass under the module, assuming the module is soldered on the top layer, a complete ground copper foil must be laid in the top layer area at the bottom of the module and well grounded, and then the routing should be done on the bottom layer.

• Clearance for Antenna Area: For models with on-board PCB antennas, the antenna projection area must be hollowed out, and no routing or copper laying is allowed.

• Keep Away from Interference Sources: The module should be kept as far away as possible from interference sources such as power transformers and high-frequency circuits.

Summary and Selection Recommendations

Ebyte's Bluetooth audio modules provide a clear differentiated path:

• Pursue ultimate sound quality and active noise cancellation, and have strong development capabilities -> Choose the Qualcomm programmable series (EWM104-BT5125/3040). You need to invest time in learning Qualcomm ADK and strictly follow its complex hardware design guidelines.

• Need rapid market launch, stable products, and cost-controllable audio functions -> Choose the classic driver-free series (E104-BT30). The focus is on correct power supply and audio circuit design, and no Bluetooth protocol stack development is required.

• Smart devices require "audio playback + data interaction" dual channels -> Choose the audio + data transmission dual-mode series (EWM104-BT60). Configuration can be done via AT commands to achieve function integration.

Regardless of which model you choose, the first key step to success is to carefully read the official Data Sheet and User Manual, especially the sections of "Specification Parameters", "Hardware Design Requirements", and "Recommended Circuits". It is strongly recommended to purchase the official test board for preliminary evaluation and verification.