Introduction: What Is a BLE 5.4 Serial-to-Bluetooth Module?
In the wave of IoT and industrial automation, Bluetooth Low Energy (BLE) has become the mainstream wireless technology for smart wearables, smart home and industrial data collection, thanks to its low power, high compatibility and easy pairing. However, for most embedded devices, directly integrating a complex Bluetooth protocol stack and meeting RF design requirements is a challenging task.
A serial-to-BLE module is purpose-built to solve this problem. It integrates the Bluetooth protocol stack, RF transceiver and necessary peripheral circuits into a small module that communicates with the user's MCU over a standard UART interface. Users simply send AT commands to quickly enable wireless data transmission, dramatically lowering the barrier to Bluetooth adoption.
The E104-BT14 series from Chengdu EBYTE Electronic Technology Co., Ltd. is a serial-to-BLE module based on the Bluetooth 5.4 protocol, with two models — E104-BT14SP (on-board PCB antenna) and E104-BT14SX (IPEX antenna interface). EBYTE also offers the EWT104-BT14SP test kit, built on the E104-BT14SP module, for fast evaluation and development.
Who Needs It: Solving Real-World Pain Points
The E104-BT14 series and EWT104-BT14SP test kit serve five core user groups:
| User Group | Typical Profile | Core Pain Point | Solution |
|---|---|---|---|
| Embedded developers | Hardware/software engineers | Need to add Bluetooth quickly without protocol-stack experience or RF design concerns | Complete serial-to-BLE module — just send AT commands over UART; no need to care about the underlying BLE protocol |
| Smart-home product managers | Product managers, system integrators | Need reliable, low-power wireless control for smart-home devices (lighting, curtains, sensors) | BLE 5.4, slave mode, OTA upgrade, flexible configuration via mobile app or AT commands |
| Industrial automation engineers | System integrators, PLC engineers | Need to transmit field device data (sensor readings, PLC status) to phones/hosts wirelessly with long range and reliability | Up to 9dBm TX power, 320m line-of-sight (SX), transparent transmission & over-the-air config for industrial use |
| IoT developers | IoT solution providers, integrators | Need to quickly validate Bluetooth prototypes, shorten cycles, cut risk | EWT104-BT14SP test kit with USB-to-serial, power, keys and LEDs — out-of-the-box debugging |
| Prototype builders | Makers, university researchers | Need a low-cost, easy, powerful Bluetooth module for rapid prototyping | Small size (as small as 10×10mm), AT-command driven, rich development resources |
Product Overview
E104-BT14SX & E104-BT14SP
Based on Bluetooth 5.4, these serial-to-BLE modules support slave role, low-power broadcasting, transparent data transmission and over-the-air configuration. Ideal for smart wearables, home automation, smart appliances, automotive, lighting, industrial IoT, smart data collection and smart control.
Version difference:
E104-BT14SX: IPEX 3rd-gen antenna interface, size 10×10mm — users can attach a high-gain external antenna for longer range (320m).
E104-BT14SP: On-board PCB antenna, size 10×14.5mm — highly integrated, no external antenna needed, suited to cost- and size-sensitive applications (200m).
EWT104-BT14SP Test Kit
The EWT104-BT14SP is a Bluetooth test kit based on the E104-BT14SP module that significantly shortens development cycles. It integrates a USB-to-serial chip, power circuit, keys, LEDs and antenna — connect it to a PC via USB and use a serial-port tool or mobile app for function testing and parameter configuration.
Features & Model Comparison
E104-BT14 Series Core Features
Bluetooth 5.4 protocol: Supports the latest BLE 5.4 standard with notable improvements in low power, connection stability and security.
Slave role: Supports the slave working role only; can connect with other EBYTE Bluetooth products and supports transparent transmission.
Up to 9dBm TX power: Stronger transmission; ~320m line-of-sight range (SX version, clear open air).
Transparent data transmission: The transmitter sends UART-received data over BLE without any processing; the receiver outputs BLE-received data over UART without any processing.
MTU up to 247 bytes: Larger packets improve throughput.
OTA firmware upgrade: Wireless upgrade via mobile app (e.g. AB OTA Demo) for easy field maintenance.
Over-the-air configuration: In slave mode, module parameters can be configured wirelessly via a mobile app without a serial cable.
iBeacon support: Switchable between normal broadcast and iBeacon broadcast for indoor positioning and advertising.
Ultra-low power: Supports low-power modes; sleep current only ~2μA, ideal for battery-powered applications.
Model Comparison & Selection Guide
| Parameter | E104-BT14SX | E104-BT14SP | EWT104-BT14SP |
|---|---|---|---|
| Form factor | RF module | RF module | Test kit (dev board) |
| Core chip | BLE 5.4 SoC | BLE 5.4 SoC | Based on E104-BT14SP |
| Antenna | IPEX 3rd-gen (external) | On-board PCB | On-board PCB |
| Size | 10×10 mm | 10×14.5 mm | 59.6×30 mm (with board) |
| Range | 320m (open) | 200m (open) | 200m (open, same as SP) |
| TX power | -14~9 dBm | -14~9 dBm | -14~9 dBm |
| Supply | 1.8~3.6V (3.3V rec.) | 1.8~3.6V (3.3V rec.) | USB 5V (on-board 3.3V LDO) |
| Operating temp | -40~+85℃ | -40~+85℃ | -40~+85℃ |
| Weight | 0.4g | 0.5g | ~10g (with board) |
| Key strengths | Ultra-long range, flexible external antenna | High integration, low cost, no external antenna | Out-of-the-box, fast evaluation, easy debugging |
| Use case | Long-range or high-gain antenna needs | Size/cost-sensitive, indoor range sufficient | Prototype validation, testing, config, learning |
EWT104-BT14SP Test Kit Details
Features:
Out of the box: Connect via USB and send AT commands through a serial tool — no soldering or wiring.
Integrated USB-to-serial: On-board USB-to-serial chip recognized by the PC as a COM port.
On-board 3.3V LDO: Powered by USB 5V or a direct 3.3V supply.
All pins brought out: E104-BT14SP pins are exposed on 2.54mm headers for external connection or secondary development.
Status LEDs: LINK (connection status) and POWER LEDs for at-a-glance status.
Reset & restore keys: RESET and RESTORE (factory reset) for easy debugging.
Pin definition (excerpt):
| No. | Pin | Function |
|---|---|---|
| 1 | GND | Ground |
| 3 | RESTORE | Factory reset (hold low 5s) |
| 5 | LINK | Connection indicator (high = connected, low = disconnected) |
| 6 | BAT_DET | Battery voltage detection |
| 7 | RESET | Reset pin, active low |
| 8 | WKP | Low-power mode (default low, UART disabled); pull high for normal mode |
| 9 | RXD | Serial input |
| 10 | TXD | Serial output |
| 13 | WKP | Low-power mode; pull high for normal mode |
| 14/15 | 3V3 | DC 3.3V output |
| 16 | VBAT | Power positive, 2.5V~5.5V, 3.3V recommended |
| 17 | NC | No connection |
| 18-28 | GND/IO | Reserved GPIO and ground |
Technical Parameters
RF Parameters
| Parameter | Specification |
|---|---|
| Bluetooth standard | BLE 5.4 |
| Frequency band | 2402~2480 MHz |
| TX power | -14~9 dBm (configurable) |
| RX sensitivity | Typical -96 dBm |
| Range | 200m (SP) / 320m (SX) (clear open air) |
| Antenna impedance | 50Ω |
Electrical Parameters
| Parameter | Min | Typical | Max | Notes |
|---|---|---|---|---|
| Supply voltage | 1.8V | 3.3V | 3.6V | 3.3V recommended |
| TX current | — | 35 mA | — | At max TX power |
| RX current | — | 1.4 mA | — | — |
| Sleep current | — | 2 μA | — | Deep sleep mode |
| Wakeup broadcast current | — | 1.2 mA | — | — |
| Sleep broadcast current | — | 2 μA | — | — |
| Operating temp | -40℃ | — | +85℃ | Industrial grade |
Serial Parameters
| Parameter | Description |
|---|---|
| Default baud rate | 115200 bps (changeable via AT commands) |
| Data bits | 8 |
| Stop bits | 1 |
| Parity | None |
Application Scenarios
Smart-Home Control
Recommended: E104-BT14SP (cost-sensitive) / E104-BT14SX (long-range coverage)
Integrate the E104-BT14 module into smart-home devices (smart lighting,
curtain motors, door locks) as a slave that can be directly connected
and controlled by a phone app. Transparent transmission lets control
commands pass through the UART to the device host. Over-the-air
configuration lets parameters be set wirelessly via the app — no serial
cable needed.
Industrial Data Collection & Monitoring
Recommended: E104-BT14SX (external high-gain antenna, long range)
At industrial sites, use E104-BT14SX to wirelessly transmit sensor data
(temperature, pressure, vibration) to handheld terminals or monitoring
PCs. The 9dBm TX power and 320m range cover most factory floors, and OTA
enables remote firmware updates to reduce maintenance cost.
Smart Wearables
Recommended: E104-BT14SP (small size, low power)
Embed E104-BT14SP into smart bands, watches and health-monitoring
patches. Its 10×14.5mm size and 2μA sleep current suit battery-powered
portable devices. As a slave, it uploads heart rate, step count and
other data to a phone app in real time.
Rapid Prototyping & Validation
Recommended: EWT104-BT14SP test kit
For engineers and makers new to Bluetooth, the EWT104-BT14SP test kit is
ideal. Connect via USB and send AT commands through a serial tool to
quickly learn the module's configuration and functions. Over-the-air
configuration and transparent transmission can also be tested via a
mobile app (e.g. nRF Connect) to quickly validate prototypes.
FAQ
Poor Transmission Range
Line-of-sight obstructions attenuate range accordingly.
Temperature, humidity and co-channel interference increase packet loss.
Ground absorption/reflection: testing near the ground degrades performance.
Seawater strongly absorbs RF; testing near the coast performs poorly.
Metal objects near the antenna or a metal enclosure heavily attenuate the signal.
Incorrect power-register settings or excessive over-the-air rate (higher rate = shorter range).
Supply below the recommended level — lower voltage reduces TX power.
Poor antenna–module matching or low antenna quality.
Module Easily Damaged
Check the supply is within the recommended range; exceeding the maximum can permanently damage the module.
Ensure supply stability — avoid large, frequent voltage fluctuations.
Follow ESD precautions during installation; high-frequency components are ESD-sensitive.
Keep humidity in check during installation; some components are moisture-sensitive.
Unless necessary, avoid operation at extremes of temperature.
How to Configure Module Parameters?
The module supports configuration via AT commands. Use a serial tool (e.g. XCOM, SSCOM) to send AT commands to set broadcast name, baud rate, TX power and other parameters. In slave mode, the module can also be configured over the air via a mobile app (e.g. nRF Connect) without a serial cable.
How to Perform OTA Upgrade?
The module supports OTA firmware upgrade. Use the mobile app "AB OTA Demo.APP", connect to the module, load the firmware file (.fot format) and start the OTA upgrade.
How to Restore Factory Settings?
Send the AT command AT+RESTORE to restore factory settings. For the EWT104-BT14SP test kit, hold the RESTORE key for 5+ seconds to restore factory settings.
About EBYTE
Founded in 2012, Chengdu EBYTE Electronic Technology Co., Ltd. is a national high-tech enterprise integrating R&D, production and sales. Headquartered in Chengdu with offices in Shenzhen, Guangzhou, Shanghai and Beijing, it serves customers in over 100 countries and regions worldwide. EBYTE focuses on industrial IoT wireless communication, with a portfolio spanning wireless modules, radio modems, industrial gateways, network I/O, industrial PCs, antennas and accessories.
Technology philosophy: EBYTE is committed to the mission of "making wireless communication simpler and the IoT world smarter," delivering stable, high-performance, cost-effective Bluetooth wireless products and solutions that drive industrial automation and intelligence.
Choosing the EBYTE E104-BT14 series and EWT104-BT14SP test kit means choosing a professional, reliable, high-efficiency Bluetooth 5.4 communication platform.
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