Bluetooth Servo Controller with Arduino & HC-05

Send an angle from your phone and watch a servo move to match. This project introduces serial Bluetooth communication in a fun, hands-on way.

What you’ll build

A wireless servo controller. The HC-05 Bluetooth module receives an angle (0–180) sent from a phone app, and the Arduino Nano drives the SG90 servo to that exact position.

Components you’ll need

Step-by-step guide

1. Set up the Arduino Nano on the breadboard with powered 5V and GND rails.
2. Wire the HC-05: VCC to 5V, GND to GND, TX to D2, and RX to D3 (use a voltage divider on RX for safety).
3. Connect the SG90 servo: red to 5V, brown to GND, and the orange signal wire to D9.
4. Upload the sketch below to the Nano.
5. On your phone, install any “Bluetooth Serial Terminal” app and pair with the HC-05 (default PIN 1234).
6. Send a number between 0 and 180 from the app and watch the servo rotate to that angle instantly.

The code

The sketch listens for a number over Bluetooth serial and moves the servo to that angle.

#include <SoftwareSerial.h>
#include <Servo.h>
SoftwareSerial bt(2,3); // HC-05 TX,RX
Servo s;
void setup(){ bt.begin(9600); s.attach(9); }
void loop(){
  if(bt.available()){
    int angle = bt.parseInt();
    if(angle>=0 && angle<=180) s.write(angle);
  }
}