Through-wall presence sensor from Wi-Fi noise

An ESP32 can read Wi-Fi channel state information, and a person walking through a room disturbs it. Turn that disturbance into a presence signal a home automation system can use.

Requirements

Read CSI (or RSSI as a fallback) from an ESP32 at 10 Hz or better

Compute a rolling variance and expose a boolean "presence" with hysteresis so it does not flicker

Publish presence over MQTT with a Home Assistant discovery payload, so it appears as a binary sensor with no manual config

A calibration command that samples an empty room for 30 seconds and sets the threshold

Work on a real ESP32 or in the Wokwi simulator with a replayed CSI capture (one is provided in the repo)

Technical Notes

ESP-IDF or Arduino core, your choice. The replayed capture lets the whole task be done without a board.

Bonus Points

Distinguish "someone walked past" from "someone is sitting still"

A tiny web page on the device showing the live variance

esp32iotmqtthome-assistantsignal-processing

Advanced

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