1. Product Overview
The DSD TECH HM-20 is an advanced Bluetooth Low Energy (BLE) module designed for seamless wireless communication. It serves as an upgraded version of the HM-10, incorporating the Texas Instruments (TI) CC2340 chip as its core component. This module supports Bluetooth 5.3 protocol, offering enhanced data transfer rates and a larger Maximum Transmission Unit (MTU) compared to its predecessors.
The HM-20 module is compatible with both iOS (iPhone) and Android (version 5.0 or later) mobile devices, facilitating integration into various projects requiring mobile connectivity. It is not designed for direct use with PC or MAC systems.
Image 1.1: DSD TECH HM-20 Bluetooth 5.3 BLE Module in its clear protective casing.
2. Technical Specifications
Below are the detailed technical specifications for the DSD TECH HM-20 module:
| Specification | Value |
|---|---|
| Model | HM-20 |
| Work Voltage (VCC) | 3.6V to 6V |
| TTL Logic Level (TX, RX) | 3.3V |
| Bluetooth Protocol | 5.3 BLE |
| Chip | TI CC2340 |
| PIN Configuration | VCC, GND, TX, RX |
| Support iOS | YES |
| Support Android | 5.0 or later |
| Support PC or MAC | NO |
| Item Weight | 0.236 ounces |
| Product Dimensions | 1.97 x 0.79 x 0.31 inches |
Image 2.1: Comparison of DSD TECH Bluetooth Module Series.
3. Setup and Installation
3.1 Module Pinout
The HM-20 module features four essential pins for connection:
- VCC: Power supply input (3.6V to 6V).
- GND: Ground connection.
- TX: Transmit data output (3.3V TTL logic level).
- RX: Receive data input (3.3V TTL logic level).
3.2 Connection Diagram
When connecting the HM-20 module to a microcontroller unit (MCU) like Arduino, ensure proper voltage levels for the TX and RX pins. The HM-20 operates at 3.3V TTL logic. If your MCU operates at 5V logic, a voltage divider or level shifter is required for the RX pin of the HM-20 to prevent damage.
Image 3.1: Example connection diagram for the HM-20 module to an Arduino/MCU, illustrating the use of a voltage divider for the RX pin when connecting to a 5V logic system.
4. Operating Instructions
4.1 AT Commands
The HM-20 module supports AT commands for configuration. These commands are largely compatible with the AT commands used by the HM-10 module, with the exception of baud rate settings. Refer to the specific AT command documentation for detailed usage and available commands to configure parameters such as module name, password, and operating mode.
4.2 Mobile Application Usage
DSD TECH provides a free mobile application to facilitate quick integration and testing of the HM-20 module with your projects. This application is available for both Android and iOS devices.
- For Android: Search for "DSD TECH Bluetooth" in the Google Play Store.
- For iOS: Search for "DSD TECH Bluetooth" in the App Store.
The application allows you to scan for available Bluetooth devices, connect to your HM-20 module, and interact with it, for example, by sending and receiving data or controlling digital outputs if configured.
Image 4.1: DSD TECH Bluetooth App - Device Scan Interface.
Image 4.2: DSD TECH Bluetooth App - Control Interface Example.
5. Important Precautions
- The Bluetooth 5.3 BLE module is not compatible with any Bluetooth 2.0 SPP (Serial Port Profile) devices. Ensure your connecting device supports BLE.
- Always verify the voltage levels when connecting the module to external hardware. The HM-20 operates with 3.3V TTL logic for its TX/RX pins. Connecting directly to 5V logic without a level shifter can damage the module.
- Handle the module with care to avoid electrostatic discharge (ESD) damage.
6. Troubleshooting
If you encounter issues with your DSD TECH HM-20 module, consider the following troubleshooting steps:
- No Power: Verify that the VCC and GND connections are correct and that the power supply is within the specified range (3.6V to 6V).
- No Connection: Ensure the module is powered on and discoverable. Check that your mobile device's Bluetooth is enabled and that you are using the correct DSD TECH Bluetooth application.
- Communication Errors: Double-check your TX/RX wiring. Confirm that the logic levels are compatible (3.3V TTL) and that any necessary voltage dividers or level shifters are correctly implemented. Ensure the baud rate settings in your MCU code match the module's configuration (if modified via AT commands).
- App Issues: If the mobile application is not functioning as expected, try restarting the app or your mobile device. Ensure the app is updated to the latest version.
7. Care and Maintenance
The DSD TECH HM-20 module is a robust electronic component, but proper care ensures its longevity and reliable operation:
- Keep the module in a dry environment, away from moisture and extreme temperatures.
- Avoid exposing the module to strong electromagnetic fields.
- Do not attempt to open the module's casing unless necessary for specific project requirements, as this may expose sensitive components.
- Clean the module gently with a dry, soft cloth if dust accumulates. Avoid using liquid cleaners.
8. Warranty and Technical Support
DSD TECH is committed to providing comprehensive support for its products:
- Technical Support: DSD TECH offers permanent technical support for the HM-20 Bluetooth 5.3 BLE Module. All technical inquiries will be addressed within one working day.
- Product Replacement: A 1-year product replacement service is provided for this module, covering manufacturing defects or malfunctions under normal use.
For technical assistance or warranty claims, please refer to the contact information provided with your purchase or visit the official DSD TECH website.