Arduino Based Window Alarm Annunciator - Circuit and Code

The Arduino Based Window Alarm Annunciator operates by interfacing an Arduino Uno microcontroller with a matrix of discrete inputs and output indicators to monitor multiple security or plant conditions simultaneously. The system uses three tactile pushbutton switches (S1 through S3) connected to external connectors (CON1 through CON7) to simulate various window or sensor trigger points. When a switch changes state, the Arduino Uno processes the digital input logic according to its programmed firmware. To manage the timing of visual and audible alert sequences without halting execution, the system relies on the elapsedMillis library in the Arduino IDE. Upon detecting a tripped sensor condition, the microcontroller drives a specific sequence across a bank of seven discrete LEDs (LED1 through LED7), causing them to flash and visually indicate which zone or condition requires attention. Simultaneously, the Arduino outputs a drive signal to a piezo buzzer or hooter to generate an audible alert. Discrete resistors are integrated into the circuit to limit current through the LEDs and properly bias the pushbutton inputs, ensuring stable digital readings and protecting the hardware components from overcurrent damage.