Smartphone Actuation: Remote Bluetooth Deadbolt

Standard RFID systems require you to carry a specific blue token in your pocket. The Bluetooth Smartphone Door Lock uses the device you are already holding. It leverages the HC-05 radio module alongside a heavy mechanical linkage to build a completely wireless deadbolt system triggered natively by a button on your Android screen.

Reading the Serial Bluetooth String (HC-05)

The hardware relies entirely on the HC-05 Bluetooth Transceiver.

1. The Connection: The HC-05 is wired to the Uno's RX/TX pins (or SoftwareSerial via pins 10, 11).
2. You pair your Android phone to the HC-05 in the Android Settings app.
3. You open a custom MIT App Inventor app or a generic "Bluetooth Terminal" app.
4. When you push the massive "UNLOCK" image on the phone screen, the app transmits the character U or a password string like open123!.
5. The Arduino runs a listening loop: if (Serial.available()) { char command = Serial.read(); }.

The Servo Kinematic Interlock

If the Arduino perfectly receives the password, it must actuate the heavy lock.

• The Wrong Approach: Using a tiny blue SG90 servo. The deadbolt friction will completely snap the plastic gears.
• The Execution: You mount a heavy MG996R Metal Gear Servo using a custom 3D printed bezel directly over the interior manual thumb-turn of the deadbolt locking mechanism.
• if (command == 'U') { lockServo.write(180); }
• The massive torque of the torque servo physically grips the brass thumb-turn and violently twists it 180 degrees, throwing the heavy steel deadbolt back into the door frame! The door is open!

Access Control Loadout

• Arduino Uno/Nano.
• HC-05 or HC-06 Bluetooth Module for short-range radio telemetry.
• MG996R High-Torque Servo Motor.
• An Android Mobile Phone running a generic Bluetooth terminal app or custom API.
• A 12V 2Amp Wall Adapter or massive 18650 Battery Pack (The servo attempting to twist a rusted deadbolt will draw a massive 1.5 Amp current spike!).