Detect people who are sitting still, and even their breathing, with ESP32 + 24/60 GHz radar
PIR sensors have a well-known problem: if you sit still, the lights go off. Millimetre-wave (mmWave) radar fixes that. It picks up micro-movements like breathing. Paired with an ESP32 and ESPHome, it has become one of the most popular maker upgrades of the last two years.
How it works
A mmWave module sends out a radio chirp at 24 GHz or 60 GHz and measures what comes back. Signal processing on the module turns those reflections into presence, distance, motion and, on the better modules, breathing and heart rate. Your ESP32 just reads the results over UART.
The modules worth knowing
- Seeed MR60BHA2 (60 GHz). This one detects breathing and heartbeat up to about 1.5 m and presence up to 6 m. The kit comes with a XIAO ESP32-C6 and pre-flashed ESPHome firmware, so it shows up in Home Assistant with no code. Good for sleep and wellbeing projects.
- Seeed MR60FDA2 (60 GHz). This is the fall-detection sibling, for elder-care builds.
- Hi-Link LD2410C (24 GHz). It’s cheap and tiny, and it’s the standard choice for “is someone in this room?” ESPHome supports it natively, with configurable distance gates.
- Hi-Link LD2450 (24 GHz). It tracks several people and reports X/Y positions, so you can do zone-based automations like “someone is at the desk” or “someone is on the sofa”.
Tips from real builds
- Mounting matters. Radar goes through thin plastic but not metal. Aim it away from fans, curtains and aquarium pumps.
- Tune the distance gates. Most false triggers come from gates set too far. Start short and increase slowly.
- Combine sensors. Radar plus a PIR, or radar plus a door sensor, gives you fast and reliable presence.
- Watch the power. Radar modules draw steady current, so they’re mains-powered sensors, not coin-cell ones.
Project ideas
- Lights that stay on while you read.
- A sleep tracker that doesn’t need a wearable.
- An office occupancy dashboard.
- A fall alert for an older relative, sent to your phone.
Bottom line
mmWave + ESP32 + ESPHome is the easiest big upgrade you can make to a smart home this year.
