This project implements a simple alarm system using an ATtiny85 microcontroller, a door opening sensor, a relay module, a car siren, and an indicator LED. The alarm activates when the door is opened, triggering the sensor, and it can be deactivated using a switch in the power line.

• ATtiny85: Microcontroller to control the alarm system.
• Door Opening Sensor: Detects door opening and triggers the alarm.
• Relay Module: Controls the activation of the car siren.
• Car Siren: Emits sound when activated by the relay.
• Indicator LED: Provides visual feedback on alarm status.
• 12V Power Supply: Powers the entire system.
• Reset/Off Switch: Used to reset or turn off the alarm.

1. Door Opening Detection:

   • The sensor detects door opening and sends a signal to ATtiny85.
   • ATtiny85 triggers the alarm when it receives the door open signal.

2. Alarm Activation:

   • ATtiny85 activates the relay module.
   • The relay module powers the car siren.
   • Indicator LED turns on to show the alarm is active.

3. Alarm Deactivation:

   • Alarm can be deactivated using the switch in the power line.
   • Switch cuts off power to the relay and siren, turning off the alarm.
   • Indicator LED turns off to indicate alarm deactivation.

• Use loop() function to monitor door opening sensor.
• When door opens and alarm is inactive, trigger the alarm.
• Activate the relay to power the siren and turn on the LED indicator.

• Ensure correct electrical connections to avoid damage.
• Customize the project by adding SMS/email notifications or other features.