The slim LD2410: a 7 × 35mm strip that hides inside switch plates, lamp bases and ceiling roses, with Bluetooth so you can tune it after it is sealed in.
The LD2410B is the long, thin member of the family: a 7 × 35mm strip with the antenna patches along its length and the connection pads at one end. That shape is the point. It slides behind a light-switch plate, along the stem of a lamp, or into a 3D-printed case barely wider than a pencil.
Electrically it matches the C. The same 24GHz radar sees people moving and sitting still, reports target distance, and talks over a 3.3V UART at 256000 baud. The same Bluetooth radio lets the HLKRadarTool app connect, so you can adjust it after the case is closed. The B came first; the C later moved the same design onto a board with a breadboard header.
What the strip gives up:
What it gains is placement freedom. Radar does not need a window: 24GHz passes through thin plastic, wood veneer and plasterboard trim, so the strip can hide completely behind a cover. Metal is the exception, and a metal backbox or foil tape in front of the antenna blinds it.
| Spec | Value |
|---|---|
| Model | HLK-LD2410B |
| Frequency band | 24GHz ISM |
| Radar type | FMCW |
| Detects | Moving and stationary people, with target distance |
| Maximum sensing distance | 5m |
| Distance resolution | 0.75m per gate |
| Coverage | ±60° |
| Board size | 7 × 35mm |
| Supply voltage | 5V |
| Logic level | 3.3V UART and OUT pin |
| Interfaces | UART and GPIO (OUT pin) |
| Default baud rate | 256000, 8N1 |
| Bluetooth | Yes, app configuration |
| Range division | Per-gate sensitivity; shields zones outside the set range |
| Mounting | Ceiling or wall |
| 3-pack contents | 3 modules with pins, 10-pin 20cm cable |
| Pack options | 1, 3 or 20 modules |
The 3-pack arrives with pins and a 10-pin, 20cm cable, which turns the hardest part of the B into a plug-in job. If yours came bare, you have two routes: solder thin wires straight to the pads, or fit a matching fine-pitch header. Either way, five connections matter: 5V, GND, TX, RX and OUT.
Then wire it like any LD2410: module TX to your microcontroller's RX, module RX to its TX, 5V and ground from the board. The UART runs at 3.3V logic, so an ESP32 or ESP32-C3 connects directly. The pinout page has the pad order and power figures, and ESP32 and Arduino wiring covers each board's UART pins.
Pick your wiring by where the strip is going:
Want to leave the soldering iron cold? The LD2410B-P is the same board with pins already fitted.
The B supports ceiling and wall mounting, and each one changes how you set the distance gates. The radar splits its range into 0.75m gates, gate 0 at the board and gate 8 at the far end, and gives each its own threshold for motion and stillness. Ranges outside the zone you set are ignored, which is how you keep the hallway out of the living room.
On a wall, mount the strip at around chest height with the antenna face pointing into the room. The ±60° cone then covers the floor area in front of it, and the far gates line up with the far wall. Set the maximum moving and still gates to that wall and nothing beyond it counts.
On a ceiling, the gates measure straight down and outwards. A person lying in bed is only two or three gates away, so the near gates do most of the work and the far gates can be switched off. Ceiling mounting also keeps the cone off windows and doorways.
| Mount | Aim | Gates that matter |
|---|---|---|
| Wall, chest height | Across the room | Up to the far wall |
| Ceiling, room centre | Straight down | The first few |
| Over a desk or bed | At the person | One or two, high still sensitivity |
Then tune from the phone:
Cone widths and real-world reach are laid out on range and field of view.
The LD2410B comes as a single module, as a 3-pack with pins and a 20cm cable, and in a multi-option bundle of one or twenty pieces. The modules are the same LD2410B in each case. What changes is how many you get and whether you still have to solve the connector yourself.
A spare strip earns its place with the B more than with any other version. A lifted pad or a cracked board ends that module, and it is far better to find that out with a second one on the bench than halfway through fitting a switch plate. Keep the spare in an antistatic bag, away from the soldering station.
How the B compares with the neighbours:
The B adds Bluetooth, so the HLKRadarTool app can tune it without wiring. The radar, protocol and 7 × 35mm strip shape are otherwise the same.
Not directly. Its pads are fine pitch, so use the supplied 10-pin cable, an adapter, or solder thin wires to the pads.
Yes. The ld2410 component supports the B at 256000 baud, including gate thresholds and a switch to turn Bluetooth off.
Yes, through thin plastic, wood and plasterboard. Metal in front of the antenna blocks it.
Best LD2410
