This library covers the complete set of serial commands for the LD2410 presence sensor, including HLK-LD2410B and HLK-LD2410C. It has no external dependencies and will work on any Arduino and ESP32 board.

The latest firmware version 2.44 is supported, providing auxiliary illumination-based controls and automatic thresholds detection.

HLK-LD2410C

HLK-LD2410B

1. It is recommended to install this library from the Arduino Library Manager (search for "MyLD2410"). However, if the Arduino Library Manager does not find it, or you prefer to install it yourself, download or clone this repository.

   • Unzip the downloaded archive in the Arduino/libraries folder.

   • Restart the Arduino IDE.

2. Include the header file: #include <MyLD2410.h> in your sketch.

MyLD2410 Documentation

• Decide which hardware serial stream you'll be using for communication. For 5V Arduino boards you must use a voltage divider (1:2 or 2:3) on the TX line to protect the RX pin of the sensor, which operates at 3.3V.

#define sensorSerial Serial1

• Create a global instance of the sensor object

MyLD2410 sensor(sensorSerial);

• In the setup() function, begin serial communication with baud rate LD2420_BAUD_RATE (256000). On ESP32-WROOM: RX_PIN(16), TX_PIN(17). Check the exact pin numbers for your board. Then call sensor.begin() to begin communication with the sensor.

sensorSerial.begin(LD2410_BAUD_RATE, SERIAL_8N1, RX_PIN, TX_PIN);

if (!sensor.begin()) {
Serial.println("Failed to communicate with the sensor");
while (true);
}

• In the loop() function, call as often as possible sensor.check(). This function returns:

  1. MyLD2410::DATA if a data frame is received

  2. MyLD2410::ACK if a command-response frame is received

  3. MyLD2410::FAIL if no useful information was processed

• Use the many convenience functions to extract/modify the sensor data (see the examples below).

• There is a useful Debug feature that prints all frames received from the sensor. To enable debugging you instantiate the sensor with a second argument set to true:

  MyLD2410 sensor(sensorSerial, true);

  Debugging can be enabled and disabled at runtime with sensor.debugOn(); and sensor.debugOff();

• Once the library is installed, navigate to: File→Examples→MyLD2410 to play with the examples. They are automatically configured for some popular boards (see the table above). For other boards, minor (trivial) modifications may be necessary. Study the board_select.h header file in each example.

  1. sensor_data - retrieves all data frames from the sensor and outputs useful information every second. Handles both basic and enhanced (engineering) modes.

     Sample output:

     Data frame #: 142
     Time stamp [ms]: 16244
     Stationary only, distance: 38cm
     STATIONARY= 100@30cm 
     signals->[ 0 0 100 90 31 13 9 7 5 ] thresholds:[ 0 0 40 40 30 30 20 20 20 ]
     Light level: 218
     Output level: HIGH
     
     Data frame #: 152
     Time stamp [ms]: 17244
     Both moving and stationary, distance: 33cm
     MOVING    = 70@30cm 
     signals->[ 70 51 64 67 24 8 8 6 3 ] thresholds:[ 50 50 40 30 20 15 15 15 15 ]
     STATIONARY= 100@91cm 
     signals->[ 0 0 100 100 51 18 16 14 7 ] thresholds:[ 0 0 40 40 30 30 20 20 20 ]
     Light level: 234
     Output level: HIGH        
     

     Data frame #: 153
     Time stamp [ms]: 17297
     No target
     Light level: 240
     Output level: LOW
     
     Data frame #: 163
     Time stamp [ms]: 18297
     No target
     Light level: 240
     Output level: LOW
     

  2. print_parameters- prints the current device parameters. Note your firmware version and upgrade it using the Bluetooth app to get the latest features.

     Sample output:

     Firmware: 2.44.24073110
     Protocol version: 1
     Bluetooth MAC address: 49:AF:7B:68:81:28
     Resolution (gate-width): 75cm
     Max range: 675cm
     Moving thresholds    [0,8]: 50 50 40 30 20 15 15 15 15
     Stationary thresholds[0,8]: 0 0 40 40 30 30 20 20 20
     No-one window: 5s
     Auxiliary Configuration: no light control
     Default output level: LOW
     Done!
     

  3. factory_reset - restores the factory default values of the sensor parameters.

  4. modify_parameters - demonstrates how to modify various sensor parameters. At the end, the original state of the sensor is restored.

  5. auto_thresholds - automatically detect the thresholds for the particular environment. This feature was introduced in firmware version 2.44.

  6. set_bt_password - sets a new Bluetooth password, or resets the password to its default value "HiLink". Be careful not to get locked out of your sensor.

     • The password must be 6 characters long. If you enter a longer password (on line 54), it will be truncated to 6 characters.

     • If you provide a shorter one, it will be padded with spaces (0x20).

     • To restore the default password, uncomment the line #define RESET_PASSWORD and flash the sketch again.

  7. set_baud_rate - sets and tests a new baud rate for communication with the sensor. Be careful not to get locked out of your sensor.

     • This is useful when you intend to use the LD2410 sensor on a board like Arduino Nano/Uno. First lower the baud rate to 38400 and then use SoftwareSerial to communicate on pins 10 (RX) and 11 (TX). Check out the board_select.h header file in sensor_data.