Arduino project · Buttons and switches · Easy
Bluetooth Phone LED Control
Use three ON/OFF button pairs in a phone app to switch three LEDs.
What you will learn
- How a phone sends single letters to the Arduino
- How a voltage divider protects a 3.3 V pin
- How to latch an output
How it works
The phone app sends a character for each button. The helper turns the character into a number. Each ON button sets an LED and each OFF button clears it, so the LED keeps its state.
Try this next
- Add a fourth LED for the next ON/OFF pair.
- Send a reply to the phone with Serial.
- Use a slider to dim an LED.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
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
Remote-controlled lamps
Press a key or a remote button. The matching lamp in the real room switches on or off.
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.
- Keypad / IR remote / phone = the controller
- LEDs = the lamps