In the rapidly evolving world of smart homes and IoT systems, detecting whether a person is present in a room has become an essential capability. From automatic lighting and climate control to security and elderly care, accurate occupancy detection enables smarter and more efficient environments.
Traditional Passive Infrared (PIR) sensors have been widely used for this purpose. However, they suffer from a major limitation: they can only detect motion. When a person remains still — working at a desk, reading a book, or sleeping — a PIR sensor may incorrectly assume the room is empty.
To address this challenge, DFRobot introduced the Fermion C4002 mmWave Human Presence Sensor, a compact radar-based sensor capable of detecting both motion and stationary human presence.
What is mmWave Technology?Imagine a sensor that can detect a person's presence even when they are sitting completely still. That's the power of Millimeter Wave (mmWave) technology.
mmWave uses high-frequency radio waves, typically between 30 GHz and 300 GHz, to detect movement, measure distance, and identify objects with remarkable precision. Unlike conventional motion sensors that rely on visible movement, mmWave can detect tiny motions such as chest movements caused by breathing, making it ideal for accurate human presence detection.
This technology is transforming industries ranging from smart homes and healthcare to automotive safety and industrial automation. It enables features such as occupancy sensing, adaptive cruise control, fall detection, and high-speed 5G communication. Although mmWave signals offer exceptional accuracy and data rates, they have a relatively short range and can be weakened by obstacles like walls and metal surfaces.
As the demand for intelligent and contactless sensing continues to grow, mmWave technology is becoming a key building block for the next generation of connected and autonomous systems.
When these waves encounter a person, they are reflected back to the sensor. By examining changes in the reflected signals, the sensor can identify:
- Human movement
- Stationary presence
- Breathing motions
- Small body movements
This capability allows the sensor to detect occupants even when they are sitting quietly or sleeping.
Key Features1. Human Presence DetectionThe sensor can reliably determine whether a person is present within its detection area, even without noticeable movement.
2. Long Detection RangeThe module offers:
- Dynamic motion detection up to 11 meters
- Static presence detection up to 10 meters
This makes it suitable for rooms, offices, classrooms, and smart home applications.
3. Wide Detection AngleWith a field of view of approximately 120° × 120°, the sensor can monitor a large area using a single module.
4. Compact DesignMeasuring only 22 mm × 26 mm, the sensor can be integrated into compact electronic projects and embedded systems.
5. Multiple Interface OptionsThe sensor supports UART communication and configurable digital output modes, making integration straightforward with popular development boards.
How It Differs from PIR SensorsPress enter or click to view image in full size
The ability to recognize stationary occupants is the most significant advantage of mmWave technology.
ApplicationsPress enter or click to view image in full size
Lights can remain ON while a person is reading or working quietly and automatically switch OFF when the room becomes truly vacant.
Energy ManagementHVAC systems can adjust room temperature based on actual occupancy, reducing energy consumption.
Elderly MonitoringThe sensor can detect human presence without using cameras, preserving privacy while improving safety.
Office Occupancy DetectionMeeting rooms and workspaces can be monitored more accurately to optimize resource utilization.
Security SystemsThe sensor can identify human presence even when intruders attempt to remain still.
Hardware Specifications- Operating Voltage: 3.6 V — 5.5 V
- Radar Frequency: 24 GHz — 24.25 GHz
- Dynamic Detection Range: Up to 11 m
- Static Detection Range: Up to 10 m
- Detection Angle: 120° × 120°
- Communication Interface: UART
- Operating Temperature: −20 °C to 85 °C
- Dimensions: 22 mm × 26 mm
The C4002 sensor can be connected to:
- Arduino
- ESP32
- Raspberry Pi
- Home Assistant
Its low power consumption and simple communication interface make it an excellent choice for IoT projects.
Advantages- Detects both moving and stationary people
- High sensitivity
- Wide coverage area
- Privacy-friendly alternative to cameras
- Compact and easy to integrate
- Suitable for smart homes and industrial applications
Like all radar-based systems, the sensor’s performance may be affected by installation position, surrounding materials, and environmental conditions. Proper placement is important to achieve optimal detection accuracy.
Product Link - click here
https://www.dfrobot.com/product-3081.html?srsltid=AfmBOorpT7uvGMy5mds7N5CAmqbqAIYP825xT8dQKeIJXzOZlTVbkezl
See you guys in the next post, where we’ll dive into some exciting hands-on projects with this sensor!
Comments