HLK-LD2410 Original Module

What the original has:

• The same detection as its successors: motion, micro-motion and stationary presence up to 5m, in 0.75m gates.
• The same serial protocol at 256000 baud, so ESPHome's ld2410 component and the common Arduino libraries work.
• An OUT pin that goes high at 3.3V when someone is present.
• A 5V supply, like the B and C.

What it lacks:

• Bluetooth. The HLKRadarTool app cannot reach it. All tuning goes through the UART.
• Breadboard pins. The connector is fine pitch; the cabled version ships with a 1.25mm-to-2.54mm Dupont lead to bridge that.

The radar copes well with its surroundings. Temperature, brightness, humidity and light changes do not trip it the way they trip a PIR sensor, and it works from inside a plastic shell with no hole in the front. That makes it good for a sealed product that gets configured once at the bench and never touched again.

Being radio-free has a quiet advantage too. Nobody nearby can open an app and change your thresholds, and there is no second transmitter on the board sharing the supply. For a sensor inside a finished product, that is one less thing to lock down.

1. Clip the fine-pitch end onto the module, checking the locking side matches the connector.
2. Label the five Dupont ends straight away with tape: 5V, GND, TX, RX, OUT.
3. Take 5V and GND from your board's 5V pin, not its 3.3V pin.
4. Cross the serial lines: module TX to board RX, module RX to board TX.
5. Leave OUT free, or run it to a GPIO for a hardware presence line.

Wire colours on these cables are not standardised, so never wire by colour alone. Match each wire to the pad names on your module's silkscreen, and confirm against the LD2410 pinout before power goes on.

For a permanent install, you can cut the cable and solder the fine-pitch end's wires to your carrier board. That keeps the module removable at its own connector while losing the loose Dupont ends. Board-by-board UART pins for the ESP32, ESP32-C3, D1 Mini and Arduino are on the wiring page.

1. Wire the module to the adapter: 5V, GND, and TX and RX crossed.
2. Open the PC tool, pick the adapter's COM port and set 256000 baud.
3. Connect, and watch the live energy per distance gate.
4. Empty the room and raise thresholds on any gate that stays lit.
5. Set the farthest moving and still gates, and the no-one delay, then write the settings.

You can also skip the PC entirely. ESPHome's ld2410 component exposes the gate thresholds, maximum gates and timeout as number entities, so you can tune from Home Assistant with the module already mounted. A minimal start:

uart:
  rx_pin: GPIO16
  tx_pin: GPIO17
  baud_rate: 256000
  parity: NONE
  stop_bits: 1

ld2410:

binary_sensor:
  - platform: ld2410
    has_target:
      name: Presence

The full YAML, with thresholds and engineering mode, is on the ESPHome page, and tool downloads are on the LD2410 Tool page.

Frequent reasons the tool will not connect:

• The adapter is set to 5V logic; switch it to 3.3V.
• TX and RX are straight-through instead of crossed.
• The baud rate was changed earlier and is no longer 256000.
• Another program, such as a serial monitor, still holds the COM port open.

If you lose track of a changed baud rate, step through the common rates in the tool until the module answers, then set it back to 256000 so every guide and library matches.

The first-generation LD2410 has no Bluetooth radio. A board described as an LD2410 with Bluetooth is B-generation hardware under the family name. That is not a bad thing, since you gain phone tuning, but it changes which one you want.

The horizontal and vertical boards differ only in how the connector leaves the board. Horizontal suits a module lying flat behind a cover; vertical suits a module standing on a carrier PCB with the antenna facing the room.

Pull the board out of the bag and check:

• The model printed on the board itself, not only the name on the box.
• Whether you want Bluetooth. If you do, the LD2410B or LD2410C name it clearly.
• That you have chosen two or ten pieces on the multi-quantity pack, whichever you meant.
• That the connector type suits your build: fine-pitch, horizontal or vertical.

The full family comparison, including the S and the C, is on LD2410 vs LD2410C vs LD2410B vs LD2410S, and the datasheet summary lists the original's electrical figures.