How to Use mmWave - C4001 24GHz Human Presence Detection Sensor (25 Meters, UART): Examples, Pinouts, and Specs

The mmWave - C4001 24GHz Human Presence Detection Sensor by DFRobot is a high-frequency sensor designed to detect human presence with exceptional accuracy. Utilizing advanced millimeter-wave (mmWave) technology, this sensor can detect human presence within a range of up to 25 meters. It features UART communication, making it easy to integrate with microcontrollers such as Arduino, Raspberry Pi, and other development platforms.

This sensor is ideal for applications requiring precise motion detection and presence sensing, such as:

• Smart home automation (e.g., lighting and HVAC control)
• Security systems and intrusion detection
• Occupancy monitoring in offices or public spaces
• Robotics and IoT projects

Below are the key technical details of the mmWave - C4001 sensor:

The mmWave - C4001 sensor has a 4-pin interface for power and communication. The pinout is as follows:

To use the mmWave - C4001 sensor in a circuit:

1. Connect the VCC pin to a 5V power source.
2. Connect the GND pin to the ground of your circuit.
3. Connect the TX pin of the sensor to the RX pin of your microcontroller.
4. Connect the RX pin of the sensor to the TX pin of your microcontroller.

• Ensure the sensor is powered with a stable 5V DC supply to avoid damage.
• The UART interface operates at 3.3V logic levels. If your microcontroller uses 5V logic, use a level shifter to prevent damage to the sensor.
• Avoid placing the sensor near metal objects or strong electromagnetic interference, as this may affect detection accuracy.
• The sensor is designed for indoor use; outdoor use may require additional protection from environmental factors.

Below is an example of how to interface the mmWave - C4001 sensor with an Arduino UNO using UART communication:

#include <SoftwareSerial.h>

// Define the RX and TX pins for SoftwareSerial
SoftwareSerial mmWaveSerial(10, 11); // RX = Pin 10, TX = Pin 11

void setup() {
  Serial.begin(9600);               // Initialize Serial Monitor at 9600 baud
  mmWaveSerial.begin(115200);       // Initialize mmWave sensor at 115200 baud
  Serial.println("mmWave Sensor Initialized");
}

void loop() {
  // Check if data is available from the sensor
  if (mmWaveSerial.available()) {
    String sensorData = "";         // Variable to store sensor data
    while (mmWaveSerial.available()) {
      char c = mmWaveSerial.read(); // Read each character from the sensor
      sensorData += c;              // Append character to the data string
    }
    Serial.println("Sensor Data: " + sensorData); // Print sensor data to Serial Monitor
  }
  delay(100); // Small delay to avoid flooding the Serial Monitor
}

• The SoftwareSerial library is used to create a secondary UART interface on pins 10 and 11 of the Arduino UNO.
• The sensor communicates at a baud rate of 115200, which is set in the mmWaveSerial.begin() function.
• The received data from the sensor is printed to the Serial Monitor for debugging and analysis.

1. No data received from the sensor:

   • Ensure the sensor is properly powered (5V DC) and connected to the correct UART pins.
   • Verify that the baud rate in your code matches the sensor's default baud rate (115200).
   • Check for loose or incorrect wiring.

2. Incorrect or garbled data:

   • Ensure the UART logic levels are compatible (3.3V for the sensor).
   • Use a level shifter if your microcontroller operates at 5V logic.

3. Detection range is inconsistent:

   • Avoid placing the sensor near reflective surfaces or metal objects.
   • Ensure the sensor is not obstructed by objects that may block mmWave signals.

4. Sensor not working after prolonged use:

   • Check the operating temperature and ensure it is within the specified range (-40°C to 85°C).
   • Verify the power supply is stable and within the required voltage range.

Q: Can the sensor detect multiple people simultaneously?
A: The mmWave - C4001 sensor is optimized for detecting human presence but does not provide detailed information about the number of people. For multi-target detection, additional processing may be required.

Q: Is the sensor suitable for outdoor use?
A: The sensor is primarily designed for indoor use. If used outdoors, ensure it is protected from environmental factors such as rain, dust, and extreme temperatures.

Q: Can I use this sensor with a Raspberry Pi?
A: Yes, the sensor can be connected to a Raspberry Pi via its UART interface. Ensure the Raspberry Pi's GPIO pins are configured for 3.3V logic levels.

Q: What is the maximum detection range?
A: The sensor can detect human presence up to 25 meters under optimal conditions.

By following this documentation, you can effectively integrate the mmWave - C4001 sensor into your projects for reliable human presence detection.