Presence sensors cost $80 a room, but an ESP32 and mmWave radar can detect your breathing for $15
Detect breathing, not just movement.
A smart home that turns off lights when occupants are still sitting on the couch is not considered smart. Presence sensors in each room, such as the Aqara Presence Sensor FP2 priced at $80 per room, can be costly. However, an ESP32 and a mmWave radar module can provide a more cost-effective solution. By utilizing ESPHome, an ESP32-C6, and an HLK-LDR2410C module, a presence sensor capable of detecting breathing can be created for around $15 per room.
PIR sensors detect movement but fail to identify when someone is still sitting or lying down. Wi-Fi sensing also suffers from the same limitation, as demonstrated by the ESPectre project, which works well for hallways but cannot determine if an individual is sleeping or sitting. Therefore, a presence sensor with the ability to detect subtle movements is required.
The ESP32-C6 board costs around $5, while mmWave radar modules like the LD2410C can be purchased for less than $10 on AliExpress. The LD2410C features standard 254mm pin headers, Bluetooth connectivity, and a larger PCB with well-spaced pins for easy connection of Dupont jumper wires. It also supports Bluetooth configuration through the HLKRadarTool app.
The sensor operates on a 24GHz radio with a range of approximately 6 meters, suitable for an office or bedroom. However, the signal weakens significantly through walls, necessitating a separate sensor for each room.
To set up the LD2410C, adjust its UART to 256000 baud and incorporate the LD2410 platform. In Home Assistant, a Presence entity and moving and still target entities are generated. Mount the module facing where you typically sit or sleep, and keep it away from fans or moving curtains to prevent false presence reports. The Bluetooth module can also identify which room a person is in, with an ESP32 functioning as a Bluetooth proxy listening for BLE advertisements from phones and watches.
Combining Bluetooth with mmWave radar enhances presence detection and allows for identification of who is present in the room.
Written by urgent.news from XDA Developers's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
