One panel that watches the whole room

The parts and their quirks

The alarm chain — priorities, not spaghetti

The panel has one status, and gas always wins: GAS! > Motion > All clear. A gas hit sounds the buzzer, force-starts the fan to vent, and writes the event; motion just flips the badge and logs. That priority logic is five lines:

// Alarm chain: gas beats motion; the buzzer follows the gas state, fan auto-vents.
bool gasBad = gas > 350;                      // real: calibrate to your MQ-2
if (gasBad && roomState != 2 && evlog) evlog->print("GAS/SMOKE - venting");
roomState = gasBad ? 2 : (motion ? 1 : 0);
alarmOut = gasBad;
if (gasBad) fan = true;                       // auto-vent on gas

// PIR: the module holds its output ~3 s per trigger — treat it as a window.
motion = millis() < motionUntil;

The dashboard

Two pages: Room (readings + status + log) and Control (light, fan, alarm state). The dht22 and mq2 presets pick the right widgets and ranges on their own:

dash.layout("Room", RICON_HOME);
dash.sensor("dht22", &temp, &hum);            // temp gauge + humidity metric
dash.sensor("mq2", &gas);                     // smoke/LPG gauge with the right range
dash.badge("Status", &roomState).labels("All clear", "Motion", "GAS!");
dash.led("Motion", &motion);                  // PIR state, live
evlog = &dash.log("Events", 6);

dash.layout("Control", RICON_BULB);
dash.toggle("Light", &light);                 // relay channel 1
dash.toggle("Fan", &fan);                     // relay channel 2
dash.led("Alarm", &alarmOut);                 // buzzer output
dash.beginAP("RisalDash-Room", "12345678");

The shipped example (examples/04_Templates/RoomMonitor) runs with no hardware — the fake MQ-2 occasionally “smells smoke” and the PIR fires at random, so you can watch the whole chain trip: badge → buzzer → log → fan. Then wire the real parts and delete the fakes. Every widget doubles as an MCP tool, so an AI agent can ask “is anyone in the room?” or turn the fan on — that's the AI-agent pattern.

Related builds

Only need intrusion? The shipped MotionSecurity template adds zones and an arming switch. Only gas safety? GasSafety does MQ-2 + MQ-7 with trip LEDs. Whole apartment? SmartHome scales the same pattern to scenes and rooms — this room panel is the single-room distillation of all three.