ESPHome HLK-LD2450 24GHz mmWave Human Presence Sensor 3-Target Tracking BH1750 ESP32-C3 WiFi BLE Proxy
24GHz Multi-Target Human Tracking Radar
This ESPHome device combines the HLK-LD2450 24GHz mmWave radar, BH1750 ambient light sensor, ESP32-C3 WiFi and Bluetooth chip, and a CH340K USB-to-serial chip.
Unlike a traditional PIR motion sensor, the HLK-LD2450 can track the real-time position of multiple targets and continue detecting a person even when there is very little body movement. It is ideal for room occupancy, smart lighting, HVAC control, indoor zone detection, and advanced Home Assistant automation.
HLK-LD2450 Radar Technology
Traditional PIR sensors mainly detect changes in infrared radiation. They work well when a person is moving, but may stop reporting occupancy when the person sits or stands still.
The HLK-LD2450 uses 24GHz FMCW millimeter-wave radar technology. It can detect small body movements and provide continuous target-position information, making it more suitable for accurate room presence detection.
Track Up to Three Targets
The HLK-LD2450 can track up to three targets simultaneously.
Instead of providing only a simple occupied or unoccupied signal, the radar can output separate tracking information for each detected target. This makes it possible to build automations based on the number and location of people inside a room.
Real-Time X/Y Position Tracking
The radar can provide useful information for each target, including:
Horizontal X coordinate
Forward Y coordinate
Distance from the radar
Target direction
Movement speed
Target number
Presence status
The coordinate data can be used in ESPHome or Home Assistant to create customized indoor detection zones.
For example, the radar can determine whether a target is located near a desk, sofa, bed, doorway, or other defined area.
Wide Detection Area
The HLK-LD2450 provides a typical detection angle of approximately ±60° and a typical maximum detection distance of up to approximately 6 meters.
A single sensor can therefore cover a large part of a normal indoor room when correctly positioned.
Works in Darkness
The radar does not depend on visible light, so it can operate during the day, at night, or in a completely dark room.
It does not use a camera or microphone and does not record images or conversations, making it suitable for privacy-sensitive indoor applications.
Custom Room Detection Zones
Using the target coordinates reported by the HLK-LD2450, you can create customized zones in ESPHome or Home Assistant.
Example zones:
Office desk
Sofa area
Bedside area
Room entrance
Reading corner
Kitchen worktop
Dining table
Meeting area
Zone-based automations can include:
Turn on the desk lamp only when someone is sitting at the desk
Activate a reading light when the sofa zone is occupied
Turn on a night light when someone approaches the bed
Start ventilation when the meeting area is occupied
Send a notification when someone enters a defined indoor zone
Turn off lights and HVAC after all targets leave the room
Zone functions depend on your ESPHome configuration and Home Assistant automation setup.
Built-In BH1750 Ambient Light Sensor
The integrated BH1750 digital light sensor measures the ambient brightness of the room in lux.
Combining radar presence information with real-time light measurements makes lighting automation more accurate and energy efficient.
Example automation:
Target detected + low ambient light = turn on the light
This prevents the lights from turning on unnecessarily when the room already has enough natural light.
The BH1750 can also be used for:
Automatic brightness adjustment
Day and night detection
Curtain automation
Smart lighting scenes
Energy-saving control
Indoor light-level monitoring
Bluetooth Proxy Enabled by Default
Bluetooth Proxy allows the device to help Home Assistant receive data from compatible nearby Bluetooth Low Energy devices.
Possible Bluetooth Proxy applications include:
BLE temperature and humidity sensors
Bluetooth plant sensors
Compatible BLE door sensors
BLE buttons
Bluetooth thermometers
Other Home Assistant-supported BLE devices
Bluetooth Proxy range and compatibility depend on the Bluetooth device, Home Assistant configuration, antenna environment, walls, and radio interference.
Bluetooth Proxy forwards compatible BLE data to Home Assistant. It does not turn the radar itself into a Bluetooth-only sensor.
Built-In CH340K for Direct Firmware Flashing
The onboard CH340K USB-to-serial chip allows the ESP32-C3 firmware to be flashed directly from a computer through USB.
An additional external USB-to-serial programmer is not required.
The CH340K connection can be used for:
Installing ESPHome firmware
Updating custom firmware
Restoring the device after a failed configuration
Viewing serial logs
Development and debugging
Reprogramming the ESP32-C3
This makes the device more convenient for both normal smart home users and ESPHome developers.
A CH340 driver may be required on some operating systems. Firmware flashing procedures and boot-mode operation can vary according to the software being used.
Technical Specifications
| Item | Specification |
|---|---|
| Radar Module | HLK-LD2450 |
| Wi-Fi Chip | ESP32-C3(4MB Flash) |
| Typical Detection Distance | Up to approximately 6m |
| Typical Detection Angle | Approximately ±60° |
| Model | PS02C3MZ |
| WiFi | 2.4GHz IEEE 802.11 b/g/n |
| Bluetooth | Bluetooth Low Energy |
| Bluetooth Proxy | Enabled by default |
Important Notes
This product supports 2.4GHz WiFi and cannot connect directly to a 5GHz-only WiFi network.
Detection range and stationary presence performance vary according to the environment.
The radar detects target position but cannot identify who the person is.
Coordinate-based zones require configuration in ESPHome or Home Assistant.
Moving curtains, fans, pets, or activity behind thin walls may cause unwanted detection.
Bluetooth Proxy compatibility depends on Home Assistant and the connected BLE device.
Some computers may require a CH340 driver before USB serial communication is available.
