ESPectre Turns ESP32 Wi-Fi Into Motion Sensor
Open-source firmware lets ESP32 boards detect movement from Wi-Fi signal changes without dedicated sensor hardware.
Updated on Nov. 6, 2026 in Semiconductors
ESPectre is firmware that detects motion by analyzing changes in Wi-Fi channel state information on ESP32 boards, removing the need for dedicated sensor hardware. It runs detection locally without sending data to the cloud.
Why it matters
The approach lets low-cost microcontrollers that already include Wi-Fi perform motion detection, which can reduce the cost and hardware required for home automation sensing. Because detection happens on the device, it avoids routing movement data through external servers.
ESPectre supports the ESP32, ESP32-S2, S3, C3, C5, and C6 boards and expects about 100 packets per second of channel state information traffic. Lightweight mode calibrates its threshold from roughly 10 seconds of quiet input, and ideal board placement falls between -40 dBm and -70 dBm signal strength.
The details
ESPectre pings the Wi-Fi gateway by default to generate the packet traffic it needs, and movement disrupts the radio route between the router and the board. The firmware offers four options: Native, ESPHome, Matter, and MicroPython, with the ESPHome component exposing entities directly in Home Assistant.
The Tech Race
ESPectre builds on the ESP32 microcontroller family, whose integrated Wi-Fi radio has long served connectivity roles but is now repurposed as a sensing channel. Its design extends the ESP32 platform beyond connectivity into home sensing, competing with dedicated PIR sensor hardware.
Home automation users can add motion detection to ESP32 boards they already own, with a colleague's build reportedly costing $5 for a Zigbee PIR setup. Because detection runs locally, motion data stays on the device rather than moving through cloud services.
The takeaway
Repurposing radios already built into low-cost boards can add sensing capability without new hardware, though users should test placement within the -40 dBm to -70 dBm signal range to get reliable results.
Further reading
Explore more on Semiconductors to see how chips like the ESP32 are reshaping connected devices.
Source note: This article includes information reported by XDA-Developers.
