Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Some links on this page are affiliate links: if you buy through them we may earn a commission, at no extra cost to you.
Short answer: this project combines a Carenuity C3-Mini ESP32-C3 board with an HLK-LD2410C 24 GHz radar module to detect radar-derived presence without a camera or microphone. A prepared demonstration may take about three minutes, but a first build normally takes longer because it requires soldering, assembly, Android setup, testing, and—if required—Home Assistant integration.
What this project builds
The project, published by Timothy Mwala on Hackster.io on April 11, 2024, is a small, low-voltage presence-sensing prototype. Its main parts are:
- A Carenuity C3-Mini based on the ESP32-C3
- An HLK-LD2410C 24 GHz radar sensor
- A radar sensor adapter
- A USB-C data cable and power source
- An Android phone running the HLK configuration app
The radar module emits and receives radio energy and evaluates movement in its detection area. The ESP32-C3 supplies power, connectivity, and a platform for later automation. The Android app is used to configure or inspect the radar module over Bluetooth. The original project also mentions Home Assistant, but it does not include a complete firmware package, ESPHome configuration, pinout, or Home Assistant setup.
This is a sensor that reports radar-detected activity or presence. It does not identify a person, count occupants, prove that a room is empty, or provide a certified security system.
#1 Best Overall
- WWZMDiB 5 Pcs PIR Sensor: When a human body enters the sensing range, the temperature difference between the body and the background causes a voltage change in the pyroelectric device. After amplification and comparison, the voltage signal is output.
- Voltage：DC 4.5-20V
- Detection Angle: <110 ° cone angle Lens size
- Detection range: 3-7 meters (10-23 feet)(adjustable)
- Two triggering modes: H: The output signal is maintained as long as a person is present. L: Triggered once with each change.
Why use mmWave instead of an ordinary motion sensor?
A passive infrared (PIR) sensor generally responds when a warm body moves across its field of view. That makes PIR inexpensive, simple, and power-efficient, but a person sitting still may eventually stop triggering it.
A 24 GHz millimeter-wave radar module can respond to much smaller movement, including movement associated with a stationary person. Results depend heavily on sensor placement, distance settings, sensitivity, reflections, and the surrounding room. “Presence” therefore means a configured radar signal is being detected—not guaranteed detection of every occupant.
| Technology | Strengths | Limitations |
|---|---|---|
| PIR | Low cost, low power, straightforward setup | May miss a person who remains still |
| 24 GHz mmWave | Can detect small movement and stationary occupants; works in darkness | More sensitive to reflections, placement, clutter, and configuration |
| Camera | Provides visual context and identification | Privacy, lighting, security, bandwidth, and processing concerns |
| Wi-Fi CSI | Can sense occupancy without a camera, microphone, or dedicated radar module | More experimental and dependent on the network and environment |
A separate project called ESPectre uses Wi-Fi channel-state information on ESP32 hardware. It is not the method used here.
Who should build it?
This is a good fit for a beginner who can solder and wants to experiment with ESP32 hardware, privacy-conscious occupancy sensing, smart lighting, or Home Assistant.
It is not the right choice if you need a finished, certified security product; battery operation without additional engineering; a no-tools installation; or safety-critical occupancy monitoring. The documented configuration path also depends on an Android phone, so iPhone-only users may not be able to follow it exactly.
Parts and tools
| Item | Purpose | Before you start |
|---|---|---|
| Carenuity C3-Mini | ESP32-C3 controller and connectivity | Confirm whether headers are already installed |
| HLK-LD2410C | 24 GHz presence radar | Confirm the exact module variant and voltage requirements |
| Radar adapter | Provides a convenient connection between the radar and controller | Check header type and orientation |
| USB-C data cable | Power and, where applicable, data communication | A charge-only cable may prevent flashing or serial communication |
| Android phone | Runs the HLK app over Bluetooth | Install the app and enable Bluetooth before testing |
| Soldering iron and solder | Installs the headers | Not needed if boards arrive pre-soldered |
| Power source | Provides regulated low-voltage USB power | Do not connect mains voltage directly |
A breadboard and jumper wires are useful as a fallback if the adapter is unavailable. During the first test, do not attach a relay or mains-powered load.
Rank #2
- Support NO(Normal Open) and COM, not support NC( Normal Close). it normally work together with another master device( control device or a professional power unit) to trigger relay
- Max mounting height:3-4M;Detection Area:4m(W)x2m(D)
- Technology:24G Microwave abd microprocessor
- Detection mode: Movement
- When walk close to door, it will detect person and trigger to open lock automatically. High-sensitivity, quick and accurate response. Specially apply in commercial, industrial and demanding of automatic access area.
What “three minutes” really means
The title is best understood as a quick demonstration claim, not a complete first-time build promise. The Hackster page requires soldering and labels its instructions as one hour, which is a more realistic expectation for a beginner.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problems- Prepared demonstration: with pre-soldered boards, the correct wiring, an installed app, and a ready power source, observing the detector may take only a few minutes.
- First build: allow extra time for identifying parts, soldering headers, checking wiring, assembling the boards, installing the app, pairing over Bluetooth, and correcting mistakes.
- Smart-home installation: firmware, Wi-Fi reporting, Home Assistant entities, automations, enclosure work, and room-specific tuning are separate stages.
Before assembly
- Verify that the board is the Carenuity C3-Mini or obtain documentation for any replacement board.
- Check whether the C3-Mini and radar adapter already have headers.
- Confirm the radar module’s voltage requirements and adapter orientation.
- Use a known data-capable USB-C cable.
- Prepare a regulated USB power source.
- Install the HLK Android app from Google Play if it is currently available for your phone.
- Keep the initial test at low voltage and disconnect all external loads.
Do not infer the C3-Mini pin mapping from another ESP32 board. The original Hackster page refers to an image for breadboard wiring but does not provide a complete textual pinout. Exact connections should be checked against the C3-Mini and HLK-LD2410C documentation before power is applied.
Documented assembly and first test
The source project describes this sequence:
- Solder long female headers to the C3-Mini.
- Solder male headers to the radar adapter.
- Mount the HLK-LD2410C on the adapter.
- If the adapter is unavailable, use a breadboard and jumper wires following a verified wiring diagram.
- Enable Bluetooth on the Android phone.
- Open the HLK configuration app.
- Power the assembled device through USB.
- Observe the sensor’s response while moving through the detection area.
- Remain still for a period and check whether the presence indication remains active.
- Walk away and observe how long the sensor takes to return to an unoccupied state.
Start with the electronics on a non-conductive surface. Inspect for solder bridges, reversed connectors, loose headers, and exposed conductors before connecting power.
Configuration and placement
Radar performance is determined as much by installation as by the module. Aim the sensor at the area you want to automate, not at the largest possible space.
- Keep fans, moving curtains, plants, doors, and rotating equipment out of the detection zone where possible.
- Be aware that furniture, metal, walls, and room geometry can create reflections or dead zones.
- Limit the detection distance so a doorway or adjacent room does not keep the target room marked occupied.
- Test the final orientation rather than relying only on a bench test.
- Use a non-metallic enclosure if the sensor must be enclosed; a metal enclosure may shield or distort the radar.
Begin with conservative sensitivity and a small detection area. Then test walking, sitting, standing still, opening doors, running fans, operating HVAC equipment, and moving pets. Leave the sensor in its final position for several hours or days before connecting it to lights, HVAC controls, or notifications.
PC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteHome Assistant: what is and is not documented
The Hackster project says the sensor can be integrated with Home Assistant, but it does not document a reproducible integration. It does not supply firmware, ESPHome YAML, MQTT topics, entity names, discovery instructions, or a verified wiring table.
Rank #3
- Operating voltage range: DC 4.5-20V
- Quiescent Current: <50uA Trigger: L can not be repeated trigger/H can be repeated trigger(Default repeated trigger)
- Delay time: 5-200S(adjustable) the range is (0.xx second to tens of second)
- Board Dimensions: 32mm*24mm
- Angle Sensor: <100 ° cone angle Lens size sensor:Diameter:23mm(Default)
A complete smart-home implementation needs three distinct layers:
- Local sensing: the radar module detects activity.
- Device reporting: firmware on the ESP32 sends a state over Wi-Fi, MQTT, ESPHome, or another supported method.
- Automation: Home Assistant uses the reported state for lights, alerts, dashboards, or HVAC rules.
Do not treat the Android app as proof that cloud connectivity is required. It is described as a Bluetooth configuration tool, while normal operation and Home Assistant reporting depend on the firmware and integration chosen.
For a simple occupancy automation, use a delay and an “occupied” condition rather than switching equipment instantly on every state change. Also test what happens when Wi-Fi, the ESP32, or the power supply fails.
Common problems
The board does not power on
Try a known-good regulated USB supply and a different cable. Inspect the headers and adapter orientation. Disconnect the radar and external accessories, then test the controller by itself. Stop immediately if a component becomes hot.
The phone cannot find the sensor
Confirm Bluetooth is enabled, the app is compatible with the phone, and the device is powered. Android permissions and app availability can change over time. The source project does not establish the app’s current compatibility or interface.
The radar powers up but reports no presence
Check the wiring and supply voltage, then test at a closer distance. Verify that the radar is not shielded by the enclosure or blocked by furniture. Review the configured distance and sensitivity settings.
Rank #4
- Motion sensor audio player detection range is up to 13ft(4m), 120° view angle. It will trigger the sound remind you when someone or animals enter and move in the monitored area.
- Music files can be customized, Download MP3 or WAV music files by computer. (Recommend the Windows 7 ) MP3 audio files playback, single track or multiply play.This product only supports USB data cable to replace voice, not TF card.The card slot is for decoration only.(Part of the audio has been downloaded for the initial product, if you need to change it, please connect to the computer to replace the audio)
- Indoor festival music decorations ,halloween and christmas party fun music,entrance door greeting, driving animals soundbox or alert. Install front doors, window frames, driveways, and anywhere you want to be playing music to motion.
- Customize your chimes, your MP3 sound file will playback automatically after the PIR sensor detects movement. sounds as you wish! Included mounting screws, ball mounting accessories, USB cable
- Operates with 3 AAA batteries (Not Included) and optional to be plugged in DC5V (USB Cable Included) for external power supply. (If you have any questions about the product, please contact us immediately and we will reply you within 24 hours.)
The detector stays occupied
Look for fans, curtains, HVAC vibration, pets, reflections, or activity beyond the intended room. Reduce the detection area or sensitivity and retest in the final location.
The detector misses a person
Check orientation, range limits, blocked radar, an overly narrow zone, and timeout behavior. A weak-reflection position or incorrect wiring can also produce false negatives.
Home Assistant cannot see the device
First prove that the sensor works locally. Then verify the firmware, Wi-Fi connection, transport method, entity configuration, and discovery settings independently. The original project does not provide enough information to troubleshoot a complete Home Assistant installation step by step.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Safety and privacy
Keep the prototype as a low-voltage electronics project. Never connect mains voltage directly to the ESP32 or radar module. If the sensor eventually controls a lamp, use an appropriately rated, enclosed relay or a certified smart plug. Mains wiring requires separate electrical-safety knowledge and should not be added casually to a beginner quick-start.
Radar is camera-free and microphone-free, but it still produces information about people’s presence. Tell occupants when occupancy sensing is installed, protect the device and network, and avoid using it as a medical monitor, emergency system, or sole intrusion alarm.
Free tools Windows power users keep installed
One-click scans. No signup required.
Alternatives
PIR sensor
Choose PIR when low cost, low power, and simple movement detection matter more than detecting someone sitting still. A PIR-plus-mmWave combination can improve responsiveness in some rooms, but it adds hardware and tuning.
Best Value
- IS335 WIRED PIR Motion Detector, 40' x 56' by Honeywell
Other LD2410-family modules
LD2410 variants and related modules differ in wiring, sensitivity, range, outputs, and tracking features. A comparable example uses a digital presence output and UART for richer data such as target distance and signal strength. Its example assigns UART to GPIO16 and GPIO17, presence to GPIO4, relay control to GPIO5, and serial communication to 115200 baud. Those assignments belong to that specific ESP32 example and must not be copied to the Carenuity C3-Mini without verification. See the referenced LD2410 implementation.
DFRobot C4001
The C4001 family offers longer-range options, including versions described as 12 m and 25 m models. That range is excessive for many rooms and can make zoning and false-positive control harder. See the comparative C4001 guide and DFRobot’s official site for current product information.
Wi-Fi CSI sensing
ESPectre uses changes in Wi-Fi channel-state information rather than a dedicated radar module. It is a separate, more experimental approach.
Recommended Free Tools
Ready-made hardware
Readers who value predictable installation over soldering can consider a finished sensor such as the Apollo Automation MSR-2. A ready-made unit may provide a better enclosure and simpler Home Assistant path, but it removes much of the educational and customization value of building the detector yourself.
Verdict
This is a worthwhile beginner electronics project if the goal is to learn how an ESP32 and 24 GHz radar module work together. It offers a privacy-conscious way to experiment with occupancy-based lighting, workspace automation, and notifications.
It is not honestly a complete three-minute build for most first-time makers. Treat three minutes as the best-case demonstration time; budget longer for soldering, wiring checks, configuration, tuning, and smart-home integration. If reliability, enclosure quality, support, and immediate Home Assistant operation matter more than learning, a finished presence sensor is usually the better choice.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Leave a Reply