1. Product Overview
The HLK-LD2402 is a static human life presence sensor developed by Hi-Link. It integrates a minimalist 24 GHz sensor hardware with intelligent algorithm firmware for human micro-motion sensing. This module is designed for precise detection of motion, micro-movement, and human presence in indoor environments, updating detection results in real time.
The module features AIoT millimeter wave sensors, high-performance 24 GHz one-to-one antennas, and peripheral circuits. Its intelligent algorithm firmware utilizes radar distance measurement technology and advanced proprietary radar signal processing to achieve accurate perception.
The HLK-LD2402 supports GPIO and UART interfaces, offering plug-and-play functionality for flexible application in various smart scenarios and terminal products. It also includes automatic generation of detection thresholds, which reduces manual debugging, improves detection accuracy, simplifies installation, and facilitates large-scale deployment.
Key Features:
- Equipped with single-chip intelligent millimeter wave sensor SoC and intelligent algorithm firmware.
- Ultra-small sensor size: 20 mm x 20 mm.
- Loads default human body sensing configuration for plug-and-play operation.
- Operates in the 24 GHz ISM band, compliant with FCC, CE, and RF spectrum regulations.
- Supports 3.3 V and 5 V power supply (3.0 V ~ 3.6 V, 4.5 ~ 5.5 V wide voltage range).
- Average operating current: 50 mA.
- Detects motion, micro-movement, and the presence of human bodies.
- Reports detection results in real time.
- Provides visualization tools for configuring detection distance interval and target disappearance delay time.
- Supports automatic generation of detection thresholds.
- Supports sensing range division, shielding interference outside the range.
- Motion sensor range up to 10 m.
- Large detection angle, coverage up to ±60°.
- Supports multiple installation methods: ceiling hanging and wall hanging.
- Independent trigger and hold state configuration with strong anti-interference capability.
Application Scenarios:
- Smart Home: Senses human presence and distance to control home appliances.
- Smart Business: Detects approaching or moving away individuals to control screen activation or device lighting.
- Smart Security: Used for induction access control, building intercom, electronic cat's eye, etc.
- Smart Lighting: Identifies and senses human presence and position for lighting equipment in public places (e.g., induction lamps, bulbs).
- Life Safety Protection: UV lamp work protection, automatic detection and alarm in dangerous places.
- Smart Home Appliances: Automatic shutdown of TVs, air conditioners when no one is present for extended periods.
- Intelligent Security: Detection and identification of intruders or individuals staying within a specified range.
2. Specifications
General Specifications:
| Parameter | Value | Unit | Remark |
|---|---|---|---|
| Supported Frequency Bands | 24 - 24.25 | GHz | Comply with FCC, CE, and NFPA certification standards |
| Maximum Sweep Bandwidth | 0.25 | GHz | - |
| Maximum Equivalent Isotropic Radiated Power | 11 | dBm | - |
| Supply Voltage | 3.0 - 3.6 (Typ. 3.3) | V | - |
| Add LDO Supply Voltage | 4.5 - 5.5 (Typ. 5) | V | Default not posted |
| Ambient Temperature | -40 to 85 | °C | - |
| Communication Method | Bluetooth-Compatible | - | - |
System Performance:
| Detection Range (Wall Mounted) | Target Type | Range | Unit |
|---|---|---|---|
| Wall Mounted | Sports human target | 10 | m |
| Micro-motion human target | 6 | m | |
| Meditation human target | 5 | m | |
| Ceiling Mounted | Sports human target | 5 | m |
| Micro-motion human target | 4 | m | |
| Meditation human target | 4 | m | |
| Lying human target | 3 | m |
Physical Dimensions:
- Size: 20 mm x 20 mm
- Board Thickness: 1.2 mm (tolerance ±10%)
- Package Weight: 0.01 kg
- Package Dimensions: 10 cm (L) x 8 cm (W) x 6 cm (H)
3. Setup and Installation
3.1. Hardware Description and Pinout
The HLK-LD2402 module features two sets of pin holes for connectivity:
- J2 (5 pin holes): Used for power supply and communication.
- J1 (SWD interface): Used for MCU program burning and debugging.
The PIN spacing is compatible with both 2.54mm and 2.00mm jack spacing.
J1 Pin Description:
| J#PIN# | Name | Function | Illustration |
|---|---|---|---|
| J1Pin1 | GND | Grounding | - |
| J1Pin2 | DIO | SWD interface data cable | 0 ~ 3.3 V |
| J1Pin3 | CLK | SWD interface clock line | 0 ~ 3.3 V |
| J1Pin4 | 3V3 | Power Input | 3.0 V ~ 3.6 V, Typ. 3.3 V |
J2 Pin Description:
| J#PIN# | Name | Function | Illustration |
|---|---|---|---|
| J2Pin1 | V | Power Input | 3.0 V ~ 3.6 V, Typ. 3.3 V (or 4.5V~5.5V with LDO) |
| J2Pin2 | IO | Used to report detection status | High level: someone is there; Low level: no one is there (0 ~ 3.3 V) |
| J2Pin3 | G | Grounding | - |
| J2Pin4 | T | UART_TX | 0 ~ 3.3 V |
| J2Pin5 | R | UART_RX | 0 ~ 3.3 V |
3.2. Connecting to a Host Computer for Debugging
To debug the HLK-LD2402 mmWave sensor firmware using a third-party serial port tool, follow these steps:
- Connect Hardware: Connect the HLK-LD2402 module to your host computer via a USB to TTL serial port adapter board. Ensure the following pin connections:
| Sensor Pin | Serial Port Adapter Board Pin |
|---|---|
| RX | TXD |
| TX | RXD |
| GND | GND |
| 3V3 | VCCIO |
- Identify Serial Port: Open your computer's Device Manager to identify the serial port number assigned to the mmWave sensor.
- Configure Serial Tool: Open your third-party serial port tool. Select the identified serial port number and set the baud rate to 115200. Then, click "Open Serial Port" (or equivalent function) to establish the connection.
Note: The host computer tool and a third-party serial port tool cannot be used simultaneously.
3.3. Installation Methods and Detection Range
The HLK-LD2402 supports two primary installation methods: ceiling-mounted and wall-mounted. Ceiling-mounted installation is generally recommended.
3.3.1. Direction Definition:
The sensor's coordinate system is defined as follows:
- X-axis: 0° direction.
- Z-axis: 90° direction.
- Y-axis: Perpendicular to the XZ plane (normal direction).
3.3.2. Ceiling Installation:
When mounted on the ceiling at a height of 3m, the HLK-LD2402's detection range forms a conical space with a bottom radius of 5m. The maximum sensing range decreases as the installation height decreases.
3.3.3. Wall Mounting:
The recommended wall mounting height is 1.5~2 m. For wall mounting, the X-axis points horizontally, the Z-axis points upward, and the Y-axis points to the detection area. The maximum motion sensing range is a conical space within 10 m in the normal direction of the sensor and within ±60° in horizontal and pitch directions.
3.4. Installation Environment Requirements
For optimal detection performance, install the product in a suitable environment. Detection may be affected by:
- Non-human objects constantly moving in the sensing area (e.g., animals, swinging curtains, large green plants near air vents).
- Large areas of strong reflective surfaces in the sensing area, or strong reflective objects facing the antenna, causing interference.
- External interference factors like air conditioners and electric fans on the ceiling when wall-mounted.
3.5. Notes on Installation
- Ensure the antenna faces the area to be detected and that there are no obstructions around the antenna.
- The sensor's installation position must be firm and stable; shaking can affect detection.
- Ensure no movement or vibration on the back of the sensor. Millimeter waves can penetrate, so the antenna back lobe might detect moving objects behind the sensor. A metal shield or back plate can be used to mitigate this.
- If using multiple 24 GHz band millimeter wave sensors, avoid facing them directly and install them as far apart as possible to prevent mutual interference.
3.6. Power Supply Considerations
The power input voltage range is 3.0 V ~ 3.6 V. The power ripple should not have a significant spectrum peak within 100 kHz. Consider electromagnetic compatibility design (e.g., ESD and lightning surge) for your specific application.
4. Operating Instructions
The HLK-LD2402 comes with factory-burned system firmware. Hi-Link provides a visual host configuration tool software to help developers configure parameters and optimize sensing effects.
4.1. Host Computer Tool Usage
Before using the host computer tool, ensure the HLK-LD2402 is connected to the computer as described in Section 3.2.
- Obtain Tool: Download the "HLK-LD2402_Tool" from the official Hi-Link website.
- Connect Device: Open the host computer tool, click "Refresh", select the correct serial port number, confirm the baud rate is 115200, and click "Connect Device".
- View/Set Parameters: The "Parameter View/Set" page allows you to view and modify sensor parameters.
4.1.1. Reading Sensor Parameters:
On the "Parameter View/Set" page, click the "Read Sensor Settings" button. A prompt "Read Parameters Successfully" will appear, displaying all current parameter values. Click "OK" to close.
4.1.2. Changing Sensor Parameters:
- Enter new parameter values on the function page.
- Click the "Write Sensor Settings" button. A "Write Parameters Successfully" prompt will appear. Click "OK" to complete.
4.1.3. Parameter Definitions:
| Parameter Name | Explanation | Parameter Range |
|---|---|---|
| Maximum distance | Sets the maximum effective detection distance. One distance door is 70 cm. | 0 - 12, accurate to 0.1m |
| Target disappearance delay time (seconds) | Delay T for target state switch from occupied to unoccupied. Timing restarts if a person is detected. Sensor reports unoccupied only after T period of no detection. | 0 - 65535 |
| Trigger threshold (dB) | Energy value threshold for switching from unmanned to manned state. Calculated via "Generate Threshold" function. | 0 - 95, accurate to 0.01 |
| Micro-motion threshold (dB) | Energy value threshold for detecting micro-motion. Calculated via "Generate Threshold" function. | 0 - 95, accurate to 0.01 |
The host computer tool also supports saving and loading parameter configurations as .xml files.
4.1.4. Real-time Data View:
The "Real-time Data" page displays target information, motion/micro-motion data, and distance over time. To view real-time data:
- Click the "Real-time Data" button. The tool automatically enables detection, and the "Start/Pause" button shows "Pause". Two line graphs will display real-time data.
- Optionally, click "Start/Pause" to pause detection. The light turns green, target distance shows "0.00 meters", and graphs stop updating.
4.1.5. Automatic Threshold Generation:
This function automatically calculates and sets appropriate detection thresholds. To generate thresholds:
- On the "Real-time Data" page, click the "Generate Threshold" button. The "Threshold Generation" window will appear.
- Input trigger and hold threshold generation coefficients (range 1.0~20.0). Click "Start / Close". The tool will generate thresholds, showing progress.
- Once complete, "Threshold generation successful." will display. Click "Close". The generated threshold is automatically saved and applied.
Important: During threshold generation, the detection range environment must be clear of human movement. Interference will prompt regeneration or indicate interference distance.
4.2. Communication Protocol
For users performing secondary development without visualization tools, the HLK-LD2402 communicates via serial port (TTL level) at a default baud rate of 115200 (1 stop bit, no parity bit). The protocol defines data format, command frames, and upload data frames.
The basic process for configuring parameters using commands is:
- Enter command mode.
- Configure/get parameter command.
- Exit command mode.
The firmware includes a parameter power-off saving function. Parameters are saved after recognizing the parameter name as 0x003F. This involves reading parameters (5.2.6) and setting parameters (5.2.7).
4.3. Reporting Data
In normal working mode, the HLK-LD2402 firmware outputs detection results via the serial port. It outputs "OFF" when no target is present and the target distance when a target is detected. In command line mode, the data format can be controlled by adjusting working mode parameters.
5. Maintenance
5.1. Firmware Update
To update the firmware using the host computer tool:
- Connect the HLK-LD2402 to the host computer tool.
- Click the "Update Firmware" function button.
- Click "Get Firmware Information" to display current device ID.
- Click "Select bin file path", choose the required .bin file, and click "Download" to start the upgrade.
A prompt will indicate "Download Successful!" or an error message if the upgrade fails.
5.2. Optimization of Automatic Threshold Generation
The automatic threshold generation function helps reduce maintenance costs by automatically adjusting the threshold value based on environmental changes in real time. This minimizes the need for regular manual adjustments, improving system stability and operational efficiency.
6. Troubleshooting
6.1. Communication Failure
If communication fails when using the host computer tool, refer to the "HLK-LD2402 Firmware Upgrade Method data package!" for guidance.
6.2. Interference During Threshold Generation
During the automatic threshold generation process, if noticeable human body movement or significant environmental interference is detected, the host computer will prompt you to regenerate the threshold or indicate the distance where interference exists. Ensure the detection range is clear during this process.
6.3. Power Supply Interference
After powering on, the radar module performs a 10-second self-test. If obvious power supply interference is present, the host computer will display a prompt. Ensure a stable power supply to avoid issues.
6.4. Inaccurate Detection or Reduced Range
- Environmental Factors: Ensure the installation environment does not contain constantly moving non-human objects, strong reflective surfaces, or external interference sources (e.g., air conditioners, fans).
- Installation Stability: Verify that the sensor is firmly and stably installed, as shaking can affect detection.
- Antenna Obstructions: Ensure the antenna faces the detection area directly and is free from obstructions.
- Back Lobe Interference: If moving objects are behind the sensor, use a metal shield or back plate to mitigate interference from the antenna's back lobe.
- Mutual Interference: When using multiple sensors, avoid facing their beams directly and maintain sufficient distance between them.
- Micro-motion Detection: For micro-motion detection, adjust the sensor's position and angle so that the angle between its normal direction and the normal direction of the detected human body is as small as possible.
7. User Tips
- For optimal performance, always ensure the sensor's field of view is clear of any unintended moving objects or reflective surfaces.
- When configuring parameters, especially thresholds, use the automatic generation function in a clear environment to get the most accurate baseline.
- If experiencing inconsistent detection, double-check the power supply stability and ensure the module is securely mounted without vibration.
8. Warranty and Support
For detailed communication protocols, advanced parameter configurations, and further technical documentation, please refer to the official HLK-LD2402 Manual PDF available at: HLK-LD2402 Manual (PDF).
For product support, technical assistance, or warranty inquiries, please contact Shenzhen Hi-Link Electronic Co., Ltd. directly.
