LD2411S Human Presence Sensor
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Overview
About LD2411S Human Presence Sensor
The LD2411S is a 24GHz mmWave radar sensor designed for human presence detection. It features both motion and micro-motion detection capabilities, with a detection range of up to 6 meters. The sensor includes Bluetooth functionality, allowing for configuration and firmware updates via the HLKRadarTool app. However, due to its unique UART communication protocol, it is not widely compatible with standard libraries. For more information on the LD2410 series, see LD2410.
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LD2411S Specifications
Complete technical specification details for LD2411S Human Presence Sensor
📊 Technical Parameters
LD2411S Pinout
The **LD2411S** is a 5-pin 24GHz mmWave radar with Bluetooth and micro-motion detection:
Visual Pinout Diagram
Pin Types
Quick Tips
**Interface**: UART (115200 baud),📡 **Technology**: 24GHz FMCW radar,👤 **Detection**: Motion + micro-motion (breathing detection),📏 **Range**: Up to 6 meters
**Field of View**: ±45° detection angle,🎯 **Precision**: ±5cm positioning accuracy,⚡ **Power**: 5V only (OUT signal is 3.3V logic),📱 **Bluetooth**: Integrated BLE for HLKRadarTool app configuration
**Protocol**: Custom UART protocol (not compatible with standard LD2410 libraries),🔧 **Custom Component**: Use github.com/Chreece/LD2411S-ESPHome,💡 **OUT Logic**: 3.3V compatible, safe for ESP32 GPIO
Pin Descriptions
| Pin Name | Type | Description | Notes |
|---|---|---|---|
1 VIN | Power | Power input | 5V DC regulated power supply |
2 GND | Power | Ground connection | |
3 TXD | Communication | UART transmit | Sends data from sensor (connect to ESP32 RX) |
4 RXD | Communication | UART receive | Receives commands (connect to ESP32 TX) |
5 OUT | Communication | Digital presence output | 3.3V HIGH when presence detected (optional) |
Wiring LD2411S to ESP32
To interface the **LD2411S** with an **ESP32** for human presence detection via UART:
Visual Wiring Diagram
Connection Status
Protocol
Pin Connections
| LD2411S Pin | Connection | ESP32 Pin | Description |
|---|---|---|---|
1 VIN Required | 5V | Power supply (5V regulated) | |
2 GND Required | GND | Ground | |
3 TXD Required | GPIO16 (RX2) | Sensor transmit to ESP32 receive | |
4 RXD Required | GPIO17 (TX2) | Sensor receive from ESP32 transmit | |
5 OUT Optional | GPIO18 | Digital presence output (optional) |
**UART2**: Use UART2 on ESP32 (GPIO16/17 are default UART2 pins)
**Baud Rate**: 115200 bps - must match in firmware configuration
**Power**: Requires 5V regulated supply (OUT signal is 3.3V logic)
**TX/RX**: Connect sensor TXD to ESP32 RX, sensor RXD to ESP32 TX
**OUT Pin**: 3.3V logic level, safe for direct ESP32 GPIO connection
**Custom Protocol**: Requires custom ESPHome component (github.com/Chreece/LD2411S-ESPHome)
**Bluetooth**: Disable BLE in firmware if using UART (may conflict)
**Configuration**: Use HLKRadarTool app for BLE configuration
**Micro-motion**: Capable of detecting breathing and micro-movements
LD2411S Troubleshooting
Common issues and solutions to help you get your sensor working
Common Issues
Issue: The ESP32 receives no data from the sensor.
Ensure correct wiring: swap TX and RX if needed, and confirm baud rate is set to 115200. Verify power is supplied at 5V.
Issue: The sensor does not detect presence even when someone is in range.
Check detection parameters using the HLKRadarTool app. Ensure UART communication is functioning correctly.
Issue: Sensor intermittently detects presence or fails to maintain detection.
Adjust detection thresholds using the HLKRadarTool app. Reposition sensor to minimize obstructions.
Issue: UART component in ESPHome reports failure to initialize.
Verify UART pins are correct, baud rate is 115200, and no other component is using the same UART bus.
Debugging Tips
Use the Serial Monitor to check for error messages and verify the sensor's output. Add debug prints in your code to track the sensor's state.
Use a multimeter to verify voltage levels and check for continuity in your connections. Ensure the power supply is stable and within the sensor's requirements.
Additional Resources
LD2411S Programming Examples
Ready-to-use code examples for different platforms and frameworks
As of now, there is no official Arduino library available for the LD2411S sensor. Due to its unique UART communication protocol at 115200 baud, existing LD2410 libraries are incompatible. Developers interested in integrating the LD2411S with Arduino are advised to refer to the sensor's datasheet and implement custom UART communication handling based on the provided protocol specifications.
The LD2411S sensor is not currently supported by the official ESPHome LD2410 component due to its different UART protocol and baud rate of 115200. However, there is a custom ESPHome component available that provides preliminary support for the LD2411S. You can find this custom component at Chreece/LD2411S-ESPHome. Please note that this is a community-developed solution and may require additional configuration and testing.
Currently, there is no official PlatformIO library available for the LD2411S sensor. Developers aiming to integrate the LD2411S with PlatformIO should refer to the sensor's datasheet and implement custom UART communication handling based on the provided protocol specifications.
At present, there is no official MicroPython library for the LD2411S sensor. Due to its unique UART communication protocol at 115200 baud, existing LD2410 libraries are incompatible. Developers interested in integrating the LD2411S with MicroPython are advised to refer to the sensor's datasheet and implement custom UART communication handling based on the provided protocol specifications.
Wrapping Up LD2411S
The ESP32 LD2411S Human Presence Sensor is a powerful Human Presence sensor that offers excellent performance and reliability. With support for multiple development platforms including Arduino, ESP-IDF, ESPHome, PlatformIO, and MicroPython, it's a versatile choice for your IoT projects.
Best Practices
For optimal performance, ensure proper wiring and follow the recommended configuration for your chosen development platform.
Safety First
Always verify power supply requirements and pin connections before powering up your project to avoid potential damage.
Ready to Start Building?
Now that you have all the information you need, it's time to integrate the LD2411S into your ESP32 project and bring your ideas to life!
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