DFRobot mmWave C4001 24GHz Human Presence Detection Sensor for Arduino & ESPHome (25 Meters, UART)

The mmWave C4001 24GHz Human Presence Detection Sensor for Arduino and ESPHome is a radar-based sensing module designed for intelligent human detection and movement monitoring. Using 24GHz millimeter-wave technology with FMCW modulation, it can detect human presence, track movement, and provide distance information for compatible microcontroller projects.

The C4001 25-meter version offers a human presence detection range of up to 16 meters and a motion detection and distance measurement range of up to 25 meters. Its radar-based sensing method can detect subtle movement, making it useful for applications where a person may remain relatively still after entering a monitored area. Actual performance depends on the installation position, target, surroundings, and configuration.

With UART serial communication, the sensor can exchange data with compatible Arduino and ESP32 boards. It can also be incorporated into suitable ESPHome and Home Assistant projects using a compatible integration. This makes it a useful choice for building automated lighting systems, occupancy-aware controls, smart rooms, and monitoring applications.

Features

• 24GHz millimeter-wave radar sensing technology

• C4001 SEN0609 long-range sensor version

• Human presence detection up to 16 meters

• Motion detection and distance measurement up to 25 meters

• FMCW modulation for radar-based sensing

• UART serial communication at a default 9600 baud rate

• 3.3V / 5V DC operating supply

• Detects subtle movement as well as larger movements

• Compatible with suitable Arduino and ESP32 projects

• Suitable for compatible ESPHome and Home Assistant integrations

• Compact module for embedded electronics projects

Applications

• Smart home presence detection

• Automatic lighting and fan control

• Occupancy monitoring for rooms and corridors

• Home Assistant automation

• Smart office energy management

• Security and movement monitoring projects

• Arduino and ESP32 radar applications

• Intelligent building automation

• Distance and velocity monitoring experiments

• IoT-based presence detection systems

How to Use

1. Check the module: Confirm that you have the C4001 SEN0609 25-meter version and review its pinout.

2. Connect the power: Connect VIN to a compatible 3.3V or 5V supply as specified for the module, and connect GND to ground.

3. Connect UART: Connect the sensor TX pin to the controller's RX pin and the sensor RX pin to the controller's TX pin. Ensure the logic levels are compatible.

4. Configure serial communication: Start with the documented default baud rate of 9600 bps.

5. Install the appropriate software: Use a compatible C4001 library for Arduino or a suitable ESPHome integration.

6. Test detection: Read the sensor output and test presence or motion detection within the intended sensing area.

7. Adjust installation: Position the sensor to cover the required area and reduce unwanted detection from nearby movement or reflective objects.

The C4001 documentation provides wiring guidance and software examples for supported controller platforms.

Important Notes

• The 25-meter specification refers to maximum motion detection and distance measurement, not guaranteed human presence detection at 25 meters.

• Human presence detection is specified up to 16 meters for this version.

• Confirm the operating voltage and pinout before connecting the sensor.

• UART TX and RX connections should be crossed between the sensor and controller.

• ESPHome integration may require a compatible external component; support can vary by firmware and integration version.

• Mounting angle, obstacles, reflective surfaces, and surrounding movement can affect detection performance.

• This sensor is intended for electronic sensing and automation projects and should not be treated as a certified life-safety device.

Package Includes

• 1 × mmWave C4001 24GHz Human Presence Detection Sensor (25m, UART)

• 1 × 5-pin header, if included with the supplied version