Part 4 · Smart Safety¶

What you'll build

A safety system that detects two kinds of hazards — gas leaks and fire (smoke) — and immediately triggers an audible alarm. The kind of always-watching system that protects homes, schools, kitchens, and commercial buildings.

Smart-city pillar: 🚨 Protection — Public Safety & Emergency Systems Components: Fire Detector, Gas Leak Sensor, Active Buzzer Time: ~2 hours total

About the workshop's 'Smoke Sensor'

The workshop coach guide refers to a "Smoke Sensor." In your kit, this is the Fire Detector module — it senses the infrared light that flames produce, which is what real smoke alarms ultimately respond to. We use it the same way the workshop intends.

Why a smart city needs this¶

Fire alarms have saved millions of lives, but they're traditionally standalone — one alarm, one room, screaming when triggered, hoping someone hears. Smart-city public safety systems network these sensors so a single trigger anywhere can:

Notify the building's occupants and the fire department simultaneously
Cut gas supply at the source automatically
Light up evacuation routes
Show first responders exactly where the fire started before they arrive

Your project is one node of that network — sense → decide → alarm.

How the system thinks¶

┌─────────────────────────┐    ┌─────────────────────────┐
│ Read Fire Detector       │    │ Read Gas Leak Sensor    │
└──────┬──────────────────┘    └──────┬──────────────────┘
       │                                │
   ┌───▼─────────────┐         ┌────────▼────────────┐
   │ Flame detected? │── Yes ──┤                     │
   └───┬─────────────┘         │   Buzzer ON         │
       │ No                    │   (alarm sounds)    │
                               │                     │
   ┌────────────────┐          │                     │
   │ Gas detected?  │── Yes ───┤                     │
   └───┬────────────┘          └─────────────────────┘
       │ No
       ▼
   System silent, keeps watching

In IF/THEN logic:

IF flame is detected → THEN buzzer ON (alarm)
IF gas is detected → THEN buzzer ON (alarm)
IF neither → THEN buzzer OFF (silent monitoring)

What you'll learn (in this Part)¶

Work through each component lesson, then bring them together in the build:

Fire Detector — senses the infrared signature of an open flame
Gas Leak Sensor — senses combustible gases like LPG or smoke vapour
Active Buzzer — makes the loud alarm sound when triggered
Build the Smart Safety System — tie everything together

Start with the Fire Detector