ESP32 Compatible Human Presence Sensors

These are mostly 24 GHz mmWave radars, and their trick is detecting people who are sitting still - breathing micro-motion is enough - where a classic PIR only sees movement. The LD2410 family is the de-facto standard for room occupancy: cheap, well documented, and the variants mostly differ in packaging and tuning (B adds Bluetooth configuration, the LD2420 is the budget pick).

Step up when you need more than occupied-or-not: the LD2450 and RD-03D track multiple targets with position coordinates, which enables zone logic - lights only over the desk, not the whole room. The MR24HPC1 and MR24HPB1 are alternative 24 GHz modules in the same space. Nearly all of these talk UART, and placement matters more than specs: radar sees through thin walls, so aim and range-limit accordingly.