one roomfirmware builds
Two ESP32-S3 boards
$12–20for the pair
- One TX and one RX on the same WiFi channel
- Presence, including people sitting still
- Breathing in spaces that opted in
- Docker-pinned build, nothing else to install
hardware
what it runs on
Three tiers, from one room to a building, each with what it buys and what it cannot do. Then the campus uses the system was designed for. No tier has been built into a real room yet, so the accuracy figures below come from simulation.
hardware
Start with two boards, and add links where breathing matters. One gateway core keeps up with about 1,200 links.
robust roomsimulated
Three or four boards, two or three links
$18–40for the room
- Breathing reported 94% → 100% of the time
- Missed breathing pauses roughly halved
- k-of-n presence quorum per space
- Time-slotted transmitters (in progress)
a buildingbuilt · awaits sensors
A gateway and many rooms
Pi 5or any mini-PC
- Rust gateway: API, WebSocket, /metrics, dashboard
- About 1,200 links per core, measured
- Event log with 30-day retention
- Replay recordings through the same pipeline
The percentages in these tiers come from simulation and the link figure from a host benchmark, not from boards in a room. Board prices are for ESP32-S3 devkits; the gateway is any small Linux machine. Consumer laptops expose RSSI only, which is enough for crude motion but not for breathing.
built for a campus without cameras
Each use maps to a tier, and each tier states what it cannot do. T0 is built. The others are research or come from existing campus IT.
Lights and AC off in empty rooms
T0Room presence, including still people. The highest value at the lowest risk.
Lab lone-worker safety
T0No motion for N minutes in a lab raises an advisory alert to the warden. It does not replace procedures.
Hostel corridors at night
T0Motion only, with no identity and no camera where one would never be acceptable.
Classroom headcount
T1 · researchCounts in coarse bins, trained per room. It cannot take attendance because it does not know who anyone is.
Library free seats
T2 · researchZone level at best. Position needs a mesh, and the first simulation says it is hard.
Evacuation sweep
T4 + T0Building counts from existing access-point analytics plus per-room occupancy. At the building level it counts devices, not people.
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