Arduino project · Smart doors and home · Hard
Smart Room Controller
The light comes on when somebody is in the room and it is dark. The fan starts above 30 degrees. The LCD shows both values.
What you will learn
- How to combine three sensors and two loads
- How steps override each other
- How to plan a bigger program
How it works
Step 2 turns the light on with motion. Step 3 turns it off in daylight. Step 4 runs the fan when hot.
Try this next
- Add hysteresis for the fan.
- Add a manual override button.
- Add a Bluetooth control.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Caution: single-phase mains (230 V AC). The wall socket, relay contacts and load in this circuit carry mains voltage, which can kill. Work only with an adult, with the plug out of the wall, switch the LIVE wire only, fit a fuse or MCB, join Earth to metal bodies, use a closed insulated box, and have an electrician check it before you power it. In the simulator everything is safe. In real life, test with a low-voltage lamp first.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino pin (change it here) | How to wire it |
|---|
Every wire, one by one
Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.
| # | Item | Qty | Search term | Buy / compare |
|---|
The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.
In the real world
A smart room
The motion sensor, the light sensor and the temperature sensor decide when the light and the fan switch on. Watch the room follow your circuit.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.
- PIR sensor = a person in the room
- Light sensor = how bright the room is
- Relay 1 = the ceiling fan
- Relay 2 = the ceiling light