Wi-Fi sensing for Home Assistant
Turn Wi-Fi devices into
presence sensors.
TOMMY uses Channel State Information (CSI) from Wi-Fi packets to detect motion and presence through walls. Everything runs on your local network.
Install
Prepare two devices and the server.
Acquire two ESP32 devices
You need at least 2 ESP32 boards per zone. Any of the supported variants work, as long as they are all on the same Wi-Fi band (2.4GHz or 5GHz).
Opens Home Assistant Supervisor and pre-fills the TOMMY repository.
Zones
Define a zone by placing devices.
A zone is the space between the devices you assign to it. Put two devices at opposite ends of a room and the zone covers that room. Place them further apart and the zone covers more.
Because Wi-Fi passes through walls, furniture, and floors, a zone is not limited to a single room. Detection covers everything between the devices, so one zone can cover multiple rooms, an entire floor, or reach between floors to cover a whole house.
Protocol
Mesh of devices, listening to each other.
Two or more ESP32 devices in a zone continuously exchange small Wi-Fi packets on 2.4 GHz or 5 GHz. The receiving device extracts Channel State Information (CSI) from each packet: a per-subcarrier description of how the signal was affected on its way through the room.
When a body enters the space between devices, CSI shifts in characteristic ways. Direct-path obstruction weakens line-of-sight. Multipath reflections change as the body adds and removes reflection surfaces. Doppler shifts from moving body parts perturb the frequency response. Even the rise and fall of a chest during breathing is enough to perturb the signal.
Detection
Motion or presence.
Each zone runs in one of two detection modes. Motion detection works on any supported device. Presence detection adds stationary occupancy, including breathing and micro-movements, but requires specific hardware and configuration.
Walking, hand movements, sitting down, getting up. Supported on all devices and configurations.
Adds stationary detection through breathing and micro-movements. Optimal: ESP32-C5 on 5 GHz, 4+ devices, High Performance mode. Capable: ESP32-C6 on 2.4 GHz, 2+ devices, Conservative or Performance mode.
Detection Mode
Performance
Tune sensitivity against network impact.
Performance mode controls how aggressively devices transmit. Higher modes capture faster movements and micro-movements like breathing, at the cost of more Wi-Fi traffic.
Minimizes network interference. May miss fast movements like quick entries or typing. Recommended for most users.
Increased transmission rate. Captures fast movements and micro-movements like running, breathing and keyboard typing. May cause Wi-Fi interference. Only recommended with ESP32-C5 on 5 GHz.
Highest transmission rate. Maximum sensitivity. May cause Wi-Fi interference. Only recommended with ESP32-C5 on 5 GHz.
Performance Mode
Higher modes increase sensitivity and Wi-Fi traffic.
Boundary
Keep detection inside the zone.
Wi-Fi signals pass through walls and reflect off surfaces, so motion from neighboring rooms can leak into a zone. Boundary mode isolates detection to the area you actually care about.
Strict boundary control. Reduces false positives from outside the zone. May miss motion at zone edges.
Reliable detection within zones with minimal leakage. The default choice for most rooms.
Captures all motion within the zone, including edges. May detect motion outside the intended zone.
Manually adjust how individual device pairs contribute to detection. For complex layouts.
Visualizer
See what TOMMY sees.
The Signal Visualizer in the dashboard streams the live CSI analysis from every device pair in a zone. Walk through the zone and watch the signal respond in real time. Use it to verify coverage, debug placement, and confirm a zone behaves the way you expect.
Home Assistant Integration
Each zone is a native motion sensor entity.
Install via HACS or as a custom component. Point the integration at your TOMMY instance over MQTT. Each zone you create in the TOMMY dashboard appears automatically as a motion sensor entity, syncing in real time as you add, rename, or remove zones.
INTEGRATION
ENTITIES
Matter Integration
Pair with any Matter controller.
Each zone can also be exposed over Matter as an occupancy sensor. Generate a QR code from the dashboard and pair it with Apple Home, Google Home, SmartThings, Home Assistant, or any other Matter-compatible controller. Setup codes are also provided for manual entry and re-pairing.
Matter pairing
Setup code
1234-567-8910
Hardware
Bring your own ESP32.
TOMMY runs on any ESP32 variant, but the C5 is the recommended choice. It's the only variant with 5 GHz support, which is required for the best presence detection.
2+ devices per zone, diminishing returns after 4. Minimum 1 m apart.
Boards with external antennas outperform those with PCB antennas.
Videos
See it in action.
Walkthroughs from the Home Assistant community. Setup, zone configuration, and use in real homes.
Pricing
Start free. Buy when you're ready.
Detection pauses 1 minute every 2 minutes.
- 1 zone
- Unlimited devices
- Home Assistant integration
- Matter integration
- Community support
- 1 zone
- Unlimited devices
- Uninterrupted detection
- Home Assistant integration
- Matter integration
- Community support
Presence detection requires compatible hardware. See docs.
Commercial use is not permitted under the standard license. If you're looking to deploy TOMMY in a commercial context, get in touch at info@tommysense.com with a short description of your use case.
Things worth knowing.
All sensing data is processed on your network. The only outbound traffic is a periodic license check and optional online device discovery, which can be replaced with mDNS or manual discovery.
See a complete breakdown of network communication →A few projects do Wi-Fi or RF-based sensing, each with different tradeoffs in hardware, ecosystem, and capabilities. We've written detailed breakdowns of how TOMMY compares.