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Fermion: C4002 mmWave Human Presence Sensor - Static & Motion Detection for Home Assistant (10m)
· MPN: SEN0691
The Fermion C4002 is a 24GHz FMCW mmWave radar module designed for true human presence detection, including motion, stationary people and micro-movements suc...
The Fermion C4002 is a 24GHz FMCW mmWave radar module designed for true human presence detection, including motion, stationary people and micro-movements such as breathing or chest expansion. It is aimed at smarter automation than traditional PIR sensors, which can miss occupants who are sitting still, reading, sleeping or working.
It connects over a standard UART interface for use with ESP32 controllers and Home Assistant projects. The module is compatible with ESPHome, with a verified YAML configuration provided so it can expose Occupancy, Distance and Energy entities after flashing.
The C4002 also supports software-configurable detection distance, helping you tune coverage to a room, sofa, desk or other functional area while reducing unwanted detection through thin walls or into neighbouring spaces. Adaptive background noise learning helps filter common radar false triggers such as swaying plants or moving curtains.
Included in the package is one Fermion C4002 mmWave Human Presence Sensor and one 5-pin header.
Features:
- 24GHz FMCW technology: Detects micro-motions such as breathing and chest expansion.
- Moving, stationary and micro-moving targets: Distinguishes targets within a 10×10 metre range.
- Hardware Ready: Standard UART interface connects easily to ESP32 controllers.
- Software Ready: Fully compatible with ESPHome (Home Assistant).
- Verified YAML configuration: Provided for immediate deployment.
- Instant Entities: Automatically exposes "Occupancy," "Distance," and "Energy" entities in Home Assistant upon flashing.
- True Static Presence Detection: Capable of detecting individuals who are sitting, sleeping, or standing completely still.
- Motion Detection: Up to 11m (Walking / Running).
- Static Detection: Up to 10m (Reading / Typing / Sleeping).
- Targeted Monitoring: Configure the sensor to cover only specific functional areas while strictly ignoring movement in adjacent backgrounds.
- Wall Penetration Management: Set a maximum distance threshold to help prevent detecting activity in neighbouring rooms.
- Adaptability: Suitable for diverse spaces, ranging from small bathrooms to large open-plan living rooms.
- Intelligent Environmental Filtering: Adaptive background noise learning filters non-human interference.
- Smart Lighting Automation: Maintains lighting based on true presence rather than large movements.
- HVAC Energy Management: Activates air conditioning or heating only when the room is actually occupied.
- Privacy-Friendly Elderly Care: Detects presence or prolonged inactivity without cameras or wearable devices.
- Concealed Security: Detects intrusion through thin non-metal obstacles such as decorations or thin walls.
Specifications:
- Operating Voltage: 3.6 ~ 5.5V
- Detection Capability: Motion, Micro-Motion / Stationary Human Body
- Max Detection Distance: Motion 11m, Micro-Motion / Stationary 10m
- Detection Angle: 120° x 120°
- Output Interface: OUT (Configurable IO), UART
- Operating Frequency: 24GHz ~ 24.25GHz
- Light Detection: 0 ~ 50 lux
- Operating Temperature: -20 ~ 85 ˚C
- Product Dimensions: 22mm x 26mm
Useful for Home Assistant presence sensing, smart lighting, HVAC control, privacy-friendly monitoring and concealed security projects.
Jargon buster
Plain-language definitions for the technical terms used above.
- C4002
- The specific model number of this mmWave radar presence sensor module. Model numbers matter because wiring, configuration files, detection range and software support are often specific to that exact module.
- ESP32
- ESP32 is a family of microcontroller modules with built-in wireless features such as Bluetooth and WiFi. Knowing this product uses an ESP32-based module helps explain how it provides wireless serial communication and firmware update features.
- ESPHome
- ESPHome is firmware and a configuration system for ESP-based devices used with Home Assistant. It matters because a supported ESPHome configuration can make the sensor easier to connect to a smart home setup without writing low-level code.
- FMCW
- Frequency-modulated continuous wave is a radar method that sends a changing radio signal and compares the reflection to estimate movement and distance. It matters for presence sensors because it can provide more detailed detection than a simple motion-only sensor.
- lux
- Lux is the standard unit for measuring how much light falls on a surface, similar to how a light meter reports brightness. A sensor that outputs lux gives readings that are easier to compare between rooms, outdoor conditions, and different projects.
- mmWave
- Short for millimetre wave, a high-frequency radio technology used here for radar-style sensing. It matters because mmWave sensors can detect very small movements, such as breathing, which helps them notice a person who is sitting still.
- Motion detection
- A camera feature that checks the image for changes that suggest something has moved. It matters because your project can use movement as a trigger instead of constantly saving or processing every frame.
- UART
- UART is a simple serial connection that sends data over separate transmit and receive wires, often labelled TX and RX. It matters because this module is designed to replace a wired UART cable with a wireless link while keeping the same serial data format.
- YAML
- YAML is a human-readable text format often used for configuration files. It matters here because the sensor’s ESPHome setup is provided as YAML, so users may need to edit that file to change options such as detection distance or exposed entities.
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