# HLK-LD2410B 24 GHz radar: specs and pinout

> A 24 GHz FMCW radar module from Hi-Link for human presence sensing, with a presence output pin and a UART.

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A 24 GHz FMCW radar module from Hi-Link for human presence sensing, with a presence output pin and a UART.

Every value cites its sourceOfficial pinout

[Buy on Compoden](https://compoden.com/products/hlk-ld2410b-24ghz-radar-sensor-6m-human-presence-detection)

## Specs

| Spec | Value | Source |
|---|---|---|
| Operating frequency | 24 GHz to 24.25 GHz | source Section 7 Table 2, p.14 |
| Supply | DC 5 V, supply capacity above 200 mA | source Section 7 Table 2, p.14; section 5.1, p.8 |
| Average operating current | 79 mA | source Section 7 Table 2, p.14 |
| IO output level | 3.3 V | source Section 5.1, p.8; Table 2 |
| UART default | 256000 baud, 1 stop bit, no parity | source Section 5.1, p.8 |
| Detection distance | 0.75 m to 6 m, adjustable | source Section 7 Table 2, p.14 |
| Detection angle | +/-60 degrees | source Section 7 Table 2, p.14 |
| Distance resolution | 0.75 m | source Section 7 Table 2, p.14 |
| Ambient temperature | -40 C to 85 C | source Section 7 Table 2, p.14 |
| Module size | 7 mm x 35 mm; 5 pin holes at 1.27 mm spacing, 0.6 mm diameter, pins not fitted by default | source Section 4.1, p.7 |

## Power

| | Value | Source |
|---|---|---|
| Supply | 5 V DC, capacity above 200 mA | source Section 7 Table 2, p.14 |
| Current | 79 mA average | source Section 7 Table 2, p.14 |

## Pinout

Pinout is from the Hi-Link manual for the bare module; the listing may add its own header, which is not documented.

| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| 1 OUT | Target status output: high when a human is detected, low when none | 3.3 V level | | source Section 4.2 Table 1, p.7 |
| 2 UART_Tx | Serial Tx pin | 3.3 V level | | source Section 4.2 Table 1, p.7 |
| 3 UART_Rx | Serial Rx pin | 3.3 V level | | source Section 4.2 Table 1, p.7 |
| 4 GND | Power ground | 0 V | | source Section 4.2 Table 1, p.7 |
| 5 VCC | Power input | 5 V | | source Section 4.2 Table 1, p.7 |

## Build with it
Project ideas for the HLK-LD2410B 24 GHz radar. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

- [Desk presence display](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20desk%20presence%20indicator%20that%20shows%20occupied%20or%20empty%20on%20an%20OLED%20using%20an%20ESP32%20and%20a%2024%20GHz%20radar%20presence%20sensor): Sensor powered at 5 V with its 3.3 V OUT read directly by the ESP32. Radar senses people: use only where occupants know and consent.
- [Room occupancy chime](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20doorway%20chime%20that%20beeps%20when%20a%20radar%20sensor%20detects%20someone%20entering%20using%20an%20Arduino%20Uno): Uno reads the 3.3 V OUT pin and supplies the sensor 5 V. Use in your own space with occupants' consent.
- [Presence timer on an LCD](https://app.soldr.ai/?prompt=I%20want%20to%20build%20a%20presence%20timer%20that%20shows%20minutes%20of%20occupancy%20on%20a%2016x2%20I2C%20LCD%20using%20an%20Arduino%20Uno%20and%20a%20radar%20presence%20sensor): Uses only the OUT pin, so the high-speed UART is not needed. Tell people in the room it is in use.

## Common mistakes

- Feeding the module 3.3 V: the manual specifies a 5 V supply (capacity above 200 mA), while the OUT and UART levels are 3.3 V ([source](https://drive.google.com/drive/folders/16zI-fium_BZeP08EyQke0rWp0BJTMvw3))
- Using the wrong baud rate: the serial port defaults to 256000 baud, 1 stop bit, no parity ([source](https://drive.google.com/drive/folders/16zI-fium_BZeP08EyQke0rWp0BJTMvw3))
- Expecting finer than 0.75 m distance steps: distance resolution is 0.75 m ([source](https://drive.google.com/drive/folders/16zI-fium_BZeP08EyQke0rWp0BJTMvw3))

## Not covered by the official source

- Manual V1.04 (2022); the separate serial protocol document is not covered here.
- Section 1 text says the farthest sensing distance is 5 m; Table 2 says 0.75 m to 6 m. Table 2 is used.

## Sources

- [link](https://drive.google.com/drive/folders/16zI-fium_BZeP08EyQke0rWp0BJTMvw3) (Shenzhen Hi-Link HLK-LD2410B User Manual V1.04, 2022-6-29, 17 pages; the maker's own download folder linked from the product page [link](https://www.hlktech.net/index.php?id=1094); file 'HLK LD2410B Life Presence Sensing Module Manual V1.04.pdf')