LD2410C 24GHz Human Presence Sensor

This compact LD2410C 24GHz radar module detects whether a person is present and/or moving within an indoor space. Unlike conventional PIR motion sensors that use body heat for detection, the 24GHz LD2410C uses 24GHz radar to detect both obvious movement and the smaller movements made by someone sitting or standing relatively still.

The module uses the LD2410-compatible interface and communication protocol and can be used with software such as Nick Reynolds' LD2410 Arduino library and the ESPHome LD2410 component. It provides a simple digital presence output, along with UART data including moving and stationary target states, approximate distance and signal energy. It also supports Bluetooth monitoring and configuration using compatible applications such as HLKRadarTool (Android / iOS).

Unlike PIR, radar can also detect through some non-metallic materials and may respond to movement beyond the intended area. Careful positioning and sensitivity adjustment may be needed to prevent detections through thin walls, doors or enclosures.

It's ideal for home automation occupancy detection, automatic lighting, display wake-up systems and other projects that need to distinguish between an empty room and a person who is present but not moving much.

The module comes with a pre-soldered 2.54mm header and is suitable for use with breadboards and jumper wires.

Which presence sensor should I choose?

The LD2410C, LD2410B and LD2420 are all 24GHz radar presence sensors capable of detecting normal movement and the smaller movements made by a relatively stationary person. The main differences are their physical format, supply requirements, configuration options and software compatibility.

Note: Sensors of this type are often described commercially as “mmWave” sensors. Strictly speaking, 24GHz has a wavelength of approximately 12.5mm, just outside the conventionally defined millimetre-wave range of 10mm to 1mm.

• The LD2410C (this product) is a convenient general-purpose option, with a compact breadboard-friendly layout, Bluetooth configuration and broad support from existing LD2410 Arduino and ESPHome integrations.
• The LD2410B-P provides similar LD2410 sensing and software compatibility in a longer, narrower format, with both pre-soldered and headerless variants available.
• The LD2420 is a separate 3.3V design with its own serial protocol and threshold-based calibration system, making it better suited to projects that specifically require native 3.3V power or its different detection characteristics.

Presence sensor comparison

	LD2410C	LD2410B-P	LD2420
Supply voltage	5V	5V	3.3V
Signal levels	3.3V compatible	3.3V compatible	3.3V
Configuration	Bluetooth or UART	Bluetooth or UART	UART
Reported target information	Separate moving and stationary target data	Separate moving and stationary target data	Presence, distance and radar energy data
Detection tuning	Separate moving and stationary sensitivity for each distance gate	Separate moving and stationary sensitivity for each distance gate	Per-gate trigger and hold thresholds with calibration support
Typical maximum range	Approximately 6m	Approximately 6m	Up to approximately 8m
Arduino compatibility	Established LD2410 libraries	Established LD2410 libraries	Uses a separate LD2420 protocol and software integration
ESPHome compatibility	ESPHome LD2410 component	ESPHome LD2410 component	Separate ESPHome LD2420 component
Physical format	Compact, breadboard-friendly PCB	Long, narrow PCB	Compact square PCB
Header options	Pre-soldered header	Pre-soldered or headerless variant	Pre-soldered header
Best suited to	General prototyping, Bluetooth tuning and established software support	Projects needing a narrow PCB or direct integration without headers	Native-3.3V projects and threshold-based calibration

Features

• 24GHz FMCW radar presence sensing
• Detects moving and relatively stationary people
• Reports moving and stationary target states separately
• Approximate target distance and signal energy data
• Detection distance configurable up to approximately 6m
• Bluetooth monitoring and configuration
• Separate moving and stationary sensitivity settings for each distance gate
• Adjustable maximum detection distance and absence delay
• Simple active-high digital occupied/unoccupied output
• LD2410-compatible UART interface
• Support from established Arduino and ESPHome integrations
• 5V supply input with 3.3V-compatible UART signals
• Pre-soldered breadboard-compatible 2.54mm header

Specifications

Sensor type	24GHz FMCW radar presence sensor
Detection	Moving and relatively stationary people
Maximum detection distance	Up to approximately 6m
Supply voltage	5V
Interfaces	UART and digital presence output
UART baud rate	256000 baud by default
Logic level	3.3V-compatible UART and digital output
Bluetooth	Monitoring and configuration
Pin spacing	2.54mm
Dimensions	Approximately 22 × 16mm
Protocol compatibility	LD2410-compatible

Resources

• LD2410 Arduino library by Nick Reynolds
• LD2410 Sensor in ESPHome
  

Pinout

1	TX	UART data transmitted by the radar module. Connect to the microcontroller RX pin.
2	RX	UART data received by the radar module. Connect to the microcontroller TX pin.
3	OUT	Digital presence output. Normally HIGH when presence is detected.
4	GND	Ground connection.
5	VCC	Power input, typically 5V.

Package Contents

• 1x LD2410C 24GHz Human Presence Sensor (headers pre-soldered)