HLK-LD2410C 24GHz Wave 5M Human Presence Radar Sensor Motion Module

Why radar beats a PIR sensor

A PIR sensor only sees movement. Radar also picks up the tiny movements of a person who is sitting or resting. Choose a situation to compare.

Specifications

Pinout

What you can build

Anywhere you need to know if someone is really there.

Wiring it to your board

Good to know: the sensor needs a 5V supply, but its signals are 3.3V. That suits ESP32 boards perfectly. On a 5V Arduino UNO, the OUT pin works fine, but use a resistor divider or level shifter on the line going into the sensor’s RX pin. The serial link runs at 256000 baud, so use a hardware serial port, not SoftwareSerial.

Basic code: simple presence with the OUT pin

This works on any Arduino or ESP32 board. Connect OUT to pin 2 (use pin 27 on ESP32, as in the table).

const int outPin = 2;
void setup() {
  pinMode(outPin, INPUT);
  Serial.begin(115200);
}
void loop() {
  if (digitalRead(outPin) == HIGH) {
    Serial.println("Person detected");
  } else {
    Serial.println("Room empty");
  }
  delay(500);
}

Basic code: distance and signal on ESP32

Install the “ld2410” library by ncmreynolds in the Arduino IDE Library Manager. This sketch prints whether the target is moving or still, and how far away it is.

#include <ld2410.h>
ld2410 radar;
void setup() {
  Serial.begin(115200);
  Serial2.begin(256000, SERIAL_8N1, 16, 17);  // RX2 = 16, TX2 = 17
  radar.begin(Serial2);
}
void loop() {
  radar.read();
  if (radar.presenceDetected()) {
    if (radar.movingTargetDetected()) {
      Serial.print("Moving, distance (cm): ");
      Serial.println(radar.movingTargetDistance());
    }
    if (radar.stationaryTargetDetected()) {
      Serial.print("Still, distance (cm): ");
      Serial.println(radar.stationaryTargetDistance());
    }
  } else {
    Serial.println("Room empty");
  }
  delay(500);
}

Questions buyers ask