LD2415H Velocity Radar Sensor

Overview

The ld2415h sensor platform allows you to use the Hi-Link HLK-LD2415H velocity radar sensor (datasheet and user manual) with ESPHome to track the velocity of objects. The sensor utilizes millimeter wave radar to measure the velocity of objects within it's field of view.

Specifications

The HLK-LD2415H is a velocity radar sensor module has the following specifications:

• K-band RF circuit operating in the 24.125GHz frequency range (customizable)
• Accurately measures object velocities from 1-240KM/H
• A precision of less than 1KM/H
• Range up to 180 meters.
• Antenna angle is 40° horizontal with a 16° pitch
• Capable of 22 samples per second
• RS-485 and TTL Serial interfaces
• Site specific angle and sensitivity configuration

Product Images

Sensor Communication

The UART is required to be set up in your configuration for this sensor to work. Use of hardware UART pins is recommended, however the HLK-LD2415H sensor is limited to a 9600 baud rate.

Serial Interface Specification

The sensor has both RS-485 and TTL serial interfaces with a pair of RX and TX pins for each interface. Either interface can be used to read or configure the sensor.

Serial Interface Command Syntax

Commands are comprised of 8, 11, or 13 bytes that are transmitted over either RX pin and responses can be received on either TX pin:

Command Format:

• Length: 8, 11, or 13 bytes
• 1st Byte: 0x43
• 2nd Byte: 0x46
• 3rd Byte: Command identifier
• Remaining Bytes: Command specific parameters

Example:

0x43 0x46 0x01 0x01 0x00 0x05 0x0d 0x0a

Supported Commands:

• 0x01 : Set speed threshold, angular compensation, and sensitivity

  Param	Default	Min	Max	Description
  1	0x01	0x01	????	Represents the minimum speed reported by the sensor.
  2	0x00	0x00	????	Compensation angle between the center of the radar beam axis and the travel direction of objects.
  3	0x05	0x01	0x0f	Radar sensitivity. Smaller values have higher sensitivity and more interference. Larger values are less sensitive and more resilient to interference.

  Example:

  >>> 0x43 0x46 0x01 0x01 0x00 0x05 0x0d 0x0a
  

• 0x02 : Set tracking mode, sample rate, and unit of measure

  Param	Default	Min	Max	Description
  1	0x01	0x00	0x02	Tracking Mode: 0x00 : Approaching and retreating 0x01 : Approaching 0x02 : Retreating
  2	0x01	0x00	????	The sample rate, higher values lower the rate. A value of 0 is ~22 samples per second, 1 is ~11.
  3	0x00	0x00	0x02	Unit of Measure: 0x00 : kph 0x01 : mph 0x02 : mps

  Example:

  >>> 0x43 0x46 0x02 0x01 0x01 0x00 0x0d 0x0a
  

• 0x03 : Set anti-vibration compensation

  Param	Default	Min	Max	Description
  1	0x05	0x00	0x70	Vibration anti-interference coefficient used to reject false positives. For example if the sensor is mounted to gently swaying pole.
  2	0x00	????	????	Undefined
  3	0x00	????	????	Undefined

  Example:

  >>> 0x43 0x46 0x03 0x05 0x00 0x00 0x0d 0x0a
  

• 0x04 : Set relay trigger duration and trigger speed threshold (only when using the photocoupler function)

  Param	Default	Min	Max	Description
  1	0x03	0x00	0xff	Relay closure duration when speed exceeds threshold.
  2	0x01	0x00	0xff	The lowest detection value for the photocoupler pickup in kph.
  3	0x00	????	????	Undefined

  Example:

  >>> 0x43 0x46 0x04 0x03 0x01 0x00 0x0d 0x0a
  

• 0x05 : Changes the Negotiation Mode (unknown purpose)

  Param	Default	Min	Max	Description
  1	0x01	0x01	0x02	Negotiation Mode: 0x01 : Custom Agreement 0x02 : Standard Protocol
  2-8				Mode 1: 0x43 0x46 0x05 0x01 0x00 0x00 0x00 0x00 0x00 0x00 Mode 2 first call: 0xfa 0x31 0x30 0x3d 0xfb Mode 2 second call: 0xfa 0x55 0xaa 0xff 0xfb

  Example:

  >>> 0x43 0x46 0x05 0x01 0x00 0x00 0x00 0x00 0x00 0x00
  <<< Switch to CSR Mode... Done.
  

• 0x07 : Read sensor configuration when in Standard Protocol mode.

  Param	Default	Min	Max	Description
  1-10				Pass 0x00 for all parameters, a response will be returned with the current configuration of the sensor.

  Example:

  >>> 0x43 0x46 0x07 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
  <<< xFFxFF\r\n
  <<< No.:20230801E v5.0\r\n
  <<< X1:01 X2:00 X3:05 X4:01 X5:00 X6:00 X7:05 X8:03 X9:01 X0:01\r\n
  

  Output parameters:

  Param	Description
  X1	Represents the minimum speed reported by the sensor.
  X2	Compensation angle between the center of the radar beam axis and the travel direction of objects.
  X3	Radar sensitivity. Smaller values have higher sensitivity and more interference. Larger values are less sensitive and more resilient to interference.
  X4	Tracking Mode: 0x00 : Approaching and retreating 0x01 : Approaching 0x02 : Retreating
  X5	The sample rate, higher values lower the rate. A value of 0 is ~22 samples per second, 1 is ~11.
  X6	Unit of Measure: 0x00 : kph 0x01 : mph 0x02 : mps
  X7	Vibration anti-interference coefficient used to reject false positives. For example if the sensor is mounted to gently swaying pole.
  X8	Relay closure time when speed exceeds Param 9.
  X9	The lowest detection value for the photocoupler pickup in kph.
  X0	Negotiation Mode: 0x01 : Custom Agreement 0x02 : Standard Protocol

ESPHome Example Configuration

Example yaml to use in esphome device config:

external_components:
  - source:
      url: https://github.com/cptskippy/esphome.ld2415h
      type: git
      ref: main
    components: ld2415h
    refresh: 0s

uart:
  tx_pin: 36
  rx_pin: 34
  baud_rate: 9600

sensor:
  - platform: ld2415h
    speed:
      name: Speed
      filters:
        # Sensor reports on speed down to 1km/h
        # we must zero out the speed manually
        # when the sensor stops reporting.
        - timeout:
            timeout: 0.1s
            value: 0
        # Sensor will constantly report speed
        # at the confgiured sample rate
        # this ensures we only report changes
        - delta: 0.1