Build your radar
A presence sensor you assemble in an afternoon: an ESP32 paired with an HLK-LD2450 mmWave module, streaming live X/Y target tracking to your dashboard.
Bill of materials
| ESP32 dev board | Any ESP32 with a spare hardware UART and USB (e.g. ESP32-DevKitC). |
| HLK-LD2450 mmWave module | 24 GHz radar; tracks up to 3 moving targets with X/Y + velocity over UART. |
| Jumper wires | 4 for the sensor UART (+2 if adding an alarm). |
| USB data cable | For flashing and power (must carry data, not charge-only). |
| Buzzer or relay (optional) | For the remote-alarm action; driven from a spare GPIO. |
| Enclosure (optional) | 3D-printed mount — STL link: TODO. |
Wiring
The LD2450 speaks UART. Connect it to a hardware serial port on the ESP32. Pin numbers below are a starting point — confirm them against your board and the firmware config.
| Sensor | ESP32 | Notes |
|---|---|---|
| LD2450 VCC | ESP32 5V | Module is 5V-powered. |
| LD2450 GND | ESP32 GND | Common ground. |
| LD2450 TX | ESP32 RX (GPIO16 — confirm) | Sensor → ESP32 data. |
| LD2450 RX | ESP32 TX (GPIO17 — confirm) | ESP32 → sensor (config). |
| Buzzer/relay + | GPIO (confirm) | Optional alarm output. |
Mount the sensor upright with a clear view of the area; the dashboard treats the device as the origin with +Y pointing away from it.
Assemble & connect
- 1Wire the LD2450 to the ESP32 per the table above (double-check TX/RX aren't swapped).
- 2If you want the remote alarm, wire a buzzer or relay to a spare GPIO.
- 3Flash the firmware from the browser — no toolchain needed.
- 4Power the ESP32 and join it to WiFi (via the firmware's provisioning / captive portal).
- 5In the dashboard, add a device to get a pairing code.
- 6Enter that code on the device to pair it (it receives its own device token).
- 7Open the device dashboard — you should see live targets. Draw zones and add rules.