1. Product Overview
The DX-BT33 is a versatile Bluetooth module developed by DX-SMART, featuring the Nordic nRF52833 chip with integrated PA Amplifiers. It supports Bluetooth Low Energy (BLE) 5.1, Thread, Zigbee, and proprietary protocols. This module is designed for multi-connection, multi-master/multi-slave, and optional relay mode applications, offering robust and flexible wireless communication solutions.
Key features include a transmit power of +22dBm, enabling long-range communication, and support for UART serial data communication. It comes with a comprehensive set of AT commands for configuration and control, and offers a complete developer profile for advanced customization.
Figure 1: DX-BT33 Bluetooth modules and associated USB-TTL adapter boards and cables.
2. Specifications
2.1. General Specifications
| Parameter | Value |
|---|---|
| Chipset | NORDIC nRF52833 + PA Amplifiers |
| Supply Voltage | 3.3V |
| Bluetooth Protocol | BLE 5.1 / Thread / Zigbee / Proprietary Protocols |
| Operating Temperature | -40°C to +105°C |
| Transmit Power | +22dBm |
| Flash Memory | 512KB |
| RAM | 128KB |
| Module Type | Module (DIP Package) |
| Condition | New |
| Origin | Mainland China |
2.2. Communication Range
- Single module connection: 233.4 meters
- Multi-module connection (up to 8 modules): 84.6 meters
2.3. Module Dimensions
The DX-BT33 module has compact dimensions for integration into various projects.
- DX-BT33: 26.6mm (Length) x 13mm (Width) x 2.3mm (Height)
- BT33-A (Adapter Board): 37.5mm (Length) x 15.7mm (Width) x 4.0mm (Height)
Figure 2: DX-BT33 module dimensions and main parameters.
3. Setup and Hardware Connection
3.1. Development Packages
The DX-BT33 is available in different development packages tailored to specific needs:
- BT33 Master Connection Dev Package: Suitable for basic single-master multi-slave applications.
- DX-BT33 Multi-Master/Multi-Slave Dev Package: Supports flexible switching between master and slave roles for complex interconnections, including relay mode.
Note: The built-in programs for multi-connection and relay mode are different. Please choose the appropriate package based on your application. For first-time users, the Master Connection Development Package is recommended for basic master-slave communication. For testing multi-master/multi-slave and relay mode communication, the Multi-Master/Multi-Slave (Single Module) Development Package is recommended.
3.2. Distinguishing Modules
To differentiate between the two module types:
- The module with a check mark on its PCB is the multi-master multi-slave module.
- The module without a check mark is the single-master multi-slave module.
Video 1: Overview of DX-BT33 modules, development packages, and how to distinguish between module types.
3.3. Pin Definitions
Understanding the pinout is crucial for proper integration. Refer to the diagram and table below for pin definitions.
Figure 3: Module pin definitions and an example wiring diagram for the BT33 development kit.
Pin Definition Description Table
| Pin number | Pin function | Illustrate |
|---|---|---|
| 1 | UART1-TX | Serial Data Output |
| 2 | UART1-RX | Serial Data Input |
| 3 | UART-CTS | UART Clear to Send, active Low |
| 4 | UART-RTS | UART Request to Send, active Low |
| 5/6/9/10/21 | P0_05/P0_04/P0_03/P0_02/P0_01 | I/O |
| 7 | SWCLK | Programmable input/output line |
| 8 | SWDIO | Debug port |
| 11 | RST | Reset |
| 12 | VBAT | Power Input Pin |
| 13/14/25 | GND | Power Ground |
| 15 | KEY | Disconnect Pin (Factory default: input) |
| 16 | WORK-STATUS | Module working status output pin |
| 17 | LINK-STATUS | Bluetooth connection status pin |
| 18 | VBUS | USB Power Input Pin |
| 19 | D- | USB D- |
| 20 | D+ | USB D+ |
| 26 | ANT | Antenna |
Lamp Status Indicators
- Search and not connected: 300ms high, 100ms low
- Connection Status: Always high
- LINK-STATUS Status Indicator Pin: High - connected, Low - not connected
4. Operating Modes
The DX-BT33 module supports two primary operating modes: Multi-Master Multi-Slave Mode and Relay Mode. These modes can be switched using AT commands.
4.1. Multi-Master Multi-Slave Mode
This mode supports simultaneous two-way communication with up to 4 masters and 4 slaves. Any of the connected masters or slaves can send data to the BT33 module, and all connected modules will receive the transmitted data. This enables complex data interactions between multiple devices.
Figure 4: Multi-Master Multi-Slave Mode, showing simultaneous communication between multiple masters and slaves.
4.2. Relay Mode
In Relay Mode, the module acts as a data bridge, forwarding data without receiving it itself. Masters cannot communicate directly with other masters, and slaves cannot communicate with other slaves. However, this mode enables multi-connection communication between masters and slaves, making it ideal for device networking and long-distance data relay transmission. It supports:
- Any master to broadcast data to all slaves.
- Any slave to broadcast data to all masters.
Figure 5: Relay Mode, showing the module acting as a data bridge between masters and slaves.
5. AT Command Set
The DX-BT33 module is configured and controlled using AT commands via UART serial communication. Below are some common AT commands:
| AT command | Command description |
|---|---|
| AT+VERSION | Query version number |
| AT+NAME | Query Bluetooth Name |
| AT+NAME<name> | Setting Bluetooth name |
| AT+BAUD | Query Baud Rate |
| AT+BAUD<baud> | Set baud rate |
| AT+STOP | Query Serial Stop Bit |
| AT+STOP<param> | Setting the Serial Stop Bit |
For a complete list of AT commands and detailed usage, please consult the product information packages available for download.
6. Free APP and SDK
The DX-SMART APP facilitates interaction with the module, allowing users to search for connection modules, change parameters, search for BLE devices, and send/receive data. This helps in faster product usage and verification.
Important Note: The DX-BT33 Bluetooth module utilizes the BLE protocol and supports switching between master, slave, and relay modes via AT commands. It cannot be directly discovered or connected through the built-in Bluetooth functionality of a standard phone or computer.
Free Android and iOS SDKs are provided to support customization and development services for your applications.
Figure 6: DX-SMART APP interface showing function selection, parameter settings, BLE search, and transparent transmission.
7. Maintenance and Handling
- Environmental Conditions: Operate and store the module within the specified temperature range (-40°C to +105°C). Avoid extreme temperatures, humidity, and corrosive environments.
- Static Electricity: The module is sensitive to electrostatic discharge (ESD). Always handle the module with appropriate ESD precautions, such as using an anti-static wrist strap and working on an anti-static mat.
- Physical Handling: Avoid applying excessive force or bending the module. Ensure proper soldering techniques if integrating into a PCB.
- Power Supply: Ensure the power supply is stable and within the specified 3.3V range to prevent damage.
8. Troubleshooting
- Module Not Powering On:
- Verify the power supply voltage is a stable 3.3V.
- Check all power connections for proper contact and polarity.
- Unable to Connect/Discover Module:
- Ensure the module is powered on and the LINK-STATUS indicator is showing the correct status (refer to Section 3.3).
- Remember that the DX-BT33 module cannot be directly discovered by standard phone/computer Bluetooth. Use the DX-SMART APP or a compatible BLE scanner that supports AT commands.
- Check the communication distance; ensure devices are within range.
- Data Transmission Issues:
- Verify UART connections (TX, RX, GND) are correct.
- Check the baud rate and other serial communication parameters set via AT commands.
- Ensure the module is in the correct operating mode (Master, Slave, or Relay) for your application.
- Confirm AT commands are being sent correctly and responses are received.
- Unexpected Behavior:
- Reset the module by cycling power or using the RST pin.
- Review your AT command sequence and application logic.
- Consult the full technical documentation for advanced debugging.
9. User Tips
- Start with the Master Connection Dev Package: If you are new to Bluetooth module development, begin with the basic Master Connection Development Package to familiarize yourself with single-master multi-slave communication before moving to more complex multi-master/multi-slave or relay modes.
- Utilize the DX-SMART APP: The provided DX-SMART APP is a valuable tool for initial testing, parameter configuration, and verifying data transmission without needing to write extensive code immediately.
- Refer to Documentation: Always keep the full technical documentation (Product Specification, Module Pinout, Module Dimensions, Package Diagram, Hardware Design Reference, Serial Test Tools, AT Command Set) handy for detailed information and advanced configurations.
- ESD Protection: Given the sensitive nature of electronic modules, always prioritize ESD protection during handling and integration to prevent damage.
10. Warranty and Support
DX-SMART is committed to providing high-quality products and technical support. This product is developed and designed by DX-SMART, a manufacturer, not a trader. We offer OEM and ODM services, including customized logos, programs, and appearance.
For any technical inquiries, problems, or support needs, please contact our after-sales team. We aim to respond to your questions within 24 hours.
- Email Support: Manager@szdx-smart.com
- Official Website: en.szdx-smart.com
The DX-BT33 module meets global certification standards, including CE, FCC, RoHS, and ISO.
Figure 7: DX-SMART technical support and certification details.
