When Software Meets the Physical World

An IoT system is software that has to care about physics. Batteries drain, radios interfere, walls attenuate signals, and a sensor in a ceiling might not be reachable for two years. The engineering is less about the code and more about what the code can and cannot assume.

The mesh

A single gateway cannot cover a building. A LoRa mesh lets low-power nodes relay each other's packets, so a 900-node deployment needs only a handful of gateways. Each node sleeps for minutes at a time and wakes to transmit a few bytes.

{
  "node_id": "n-0418",
  "mesh": {
    "protocol": "lorawan",
    "band": "eu_868",
    "spreading_factor": 7,
    "battery_mv": 3120,
    "hops_to_gateway": 2
  },
  "reading": {
    "temp_c": 22.4,
    "rh_pct": 48.1,
    "co2_ppm": 612,
    "ts": "2026-07-19T08:14:02Z"
  }
}

Telemetry ingestion

Thousands of nodes produce a firehose of small messages. The ingestion path buffers, deduplicates, and writes to a timeseries store where downsampled views keep queries fast even after years of data accumulate.

-- average CO2 per floor, per hour, from raw 30s samples
SELECT
  floor_id,
  date_trunc('hour', ts) AS hour,
  avg(co2_ppm)          AS avg_co2,
  max(co2_ppm)          AS peak_co2,
  count(*)              AS samples
FROM sensor_readings
WHERE ts > now() - interval '24 hours'
GROUP BY floor_id, hour
ORDER BY hour DESC, floor_id;

The sensor is cheap. The decision it enables is not. Spend the effort on the path from reading to action.— IoT Mesh

The payoff is a building that knows itself — a live floorplan drawn from its own sensors, an HVAC loop that reacts to actual occupancy, a maintenance alert before a pump fails. Software, finally, touching the world it always described.