Telemetry and display

Sensors are sampled every 20 seconds. The LCD immediately displays the latest sample. Every 10 minutes, firmware averages the sampling window (about 30 readings), recomputes AQI from averaged concentrations, and uploads one record. The first upload is attempted shortly after boot.

{
  "pms_data": { "pm1_0": 5, "pm2_5": 12, "pm10_0": 18, "provider": "pms5003" },
  "aqi": 57,
  "temperature_data": { "temperature": 31.2, "humidity": 64.5, "heat_index": 36.8, "provider": "dht22" },
  "location": { "lat": 24.8607, "lon": 67.0011, "provider": "mobile" }
}

The request goes to {BACKEND_BASE_URL}/data with X-Device-ID and X-Device-Key. Location is omitted when coordinates are unset. Uploads are skipped when Wi-Fi is down, credentials are missing, or readings are incomplete; the next scheduled tick retries.

Display

Right and Left cycle through three flicker-free, fixed-width screens:

1. AQI category and PM2.5 concentration
2. Temperature, heat index, and humidity
3. Wi-Fi/IP plus last upload status and age

Settings and Boot buttons are disabled on the reference pinout. The display’s AQI category uses the US EPA bands.