finalproject.c

/*
program: finalproject.c
author: firstName lastName
date: July 30 2026
purpose: Home Security System simulation using the DeviceAlpha board
*/

#include <stdio.h>
#include "deviceAlpha.h"

/* system states */
#define STATE_DISARMED	0
#define STATE_ARMED	1
#define STATE_ALARM	2

/* user-defined function prototypes */
void waitForStartCommand(void);
void initializeSystem(void);
void waitForButtonRelease(int button);
void runArmingCountdown(void);
void activateAlarm(void);
void resetSystem(void);

int main(void)
{
	int currentState = STATE_DISARMED;	/* current state of the system */
	int systemRunning = 1;			/* 1 = keep running, 0 = exit */

	/* step 1: validated start prompt (only 'Y' or 'y' is accepted) */
	waitForStartCommand();

	/* step 2: initialize the board and show the ambient temperature */
	initializeSystem();

	/* step 3: main state machine loop */
	while (systemRunning)
	{
		switch (currentState)
		{
			case STATE_DISARMED:
				if (GetPushButtonState(PB1) == PRESSED)
				{
					/* start the arming sequence */
					waitForButtonRelease(PB1);
					runArmingCountdown();
					currentState = STATE_ARMED;
				}
				else if (GetPushButtonState(PB4) == PRESSED)
				{
					/* exit is only allowed while disarmed */
					waitForButtonRelease(PB4);
					printf("Exiting the Home Security System. Goodbye!\n");
					systemRunning = 0;
				}
				break;

			case STATE_ARMED:
				if (GetPushButtonState(PB2) == PRESSED)
				{
					/* simulated motion detection -> alarm */
					waitForButtonRelease(PB2);
					printf("Motion detected! ALARM activated!\n");
					activateAlarm();
					currentState = STATE_ALARM;
				}
				else if (GetPushButtonState(PB3) == PRESSED)
				{
					/* disarm before any motion was detected */
					waitForButtonRelease(PB3);
					resetSystem();
					currentState = STATE_DISARMED;
				}
				else if (GetPushButtonState(PB4) == PRESSED)
				{
					/* cannot exit while the system is armed */
					waitForButtonRelease(PB4);
					printf("System is ARMED! Please disarm the system (PB3) before exiting.\n");
				}
				break;

			case STATE_ALARM:
				if (GetPushButtonState(PB3) == PRESSED)
				{
					/* disarm stops the alarm and resets everything */
					waitForButtonRelease(PB3);
					resetSystem();
					currentState = STATE_DISARMED;
				}
				else if (GetPushButtonState(PB4) == PRESSED)
				{
					/* cannot exit while the alarm is active */
					waitForButtonRelease(PB4);
					printf("ALARM is active! Please disarm the system (PB3) before exiting.\n");
				}
				break;
		}

		Wait(50);	/* small pause between button polls (debounce) */
	}

	return 0;
}

/*
 * waitForStartCommand
 * Keeps prompting until the user enters 'Y' or 'y'.
 * Any other input (wrong letter, number, empty line) is rejected.
 */
void waitForStartCommand(void)
{
	char startCharacter = '\0';
	int extraCharacter;
	int validStart = 0;

	while (!validStart)
	{
		printf("Enter 'Y' to start the Home Security System: ");
		startCharacter = (char)getchar();

		/* clear the rest of the input line */
		if (startCharacter != '\n')
		{
			extraCharacter = getchar();
			while (extraCharacter != '\n' && extraCharacter != EOF)
			{
				extraCharacter = getchar();
			}
		}

		if (startCharacter == 'Y' || startCharacter == 'y')
		{
			validStart = 1;
		}
		else
		{
			printf("Invalid input! You must enter 'Y' or 'y' to start.\n");
		}
	}
}

/*
 * initializeSystem
 * Turns every component off, shows the current temperature on the
 * 7-Segment display for a short time, then clears the display and
 * reports that the system is in the idle (disarmed) state.
 */
void initializeSystem(void)
{
	double currentTemperature;

	SetLEDState(YELLOW_LED, OFF);
	SetLEDState(GREEN_LED, OFF);
	SetLEDState(RED_LED, OFF);
	SetBuzzerState(BUZZER, OFF);

	currentTemperature = GetTemperature(TEMPERATURE_SENSOR);
	printf("Current temperature: %.2f degrees Celsius\n", currentTemperature);
	DisplayDoubleValue(currentTemperature, 2);

	Wait(2000);	/* let the user observe the ambient temperature */
	ClearSevenSegmentDisplay();

	printf("System is DISARMED. PB1 = arm, PB4 = exit.\n");
}

/*
 * waitForButtonRelease
 * Busy-waits until the given push button is released, so one physical
 * press is handled exactly once.
 */
void waitForButtonRelease(int button)
{
	while (GetPushButtonState(button) == PRESSED)
	{
		;	/* wait for the release */
	}
}

/*
 * runArmingCountdown
 * Shows a 3 second countdown on the 7-Segment display while blinking
 * the YELLOW led, then turns the GREEN led on (system armed).
 */
void runArmingCountdown(void)
{
	int countdownSecond;
	int blinkNumber;

	printf("Arming the system...\n");

	for (countdownSecond = 3; countdownSecond >= 1; countdownSecond--)
	{
		DisplayIntValue(countdownSecond);

		/* two yellow blinks per second (4 x 250 ms = 1 second) */
		for (blinkNumber = 0; blinkNumber < 2; blinkNumber++)
		{
			SetLEDState(YELLOW_LED, ON);
			Wait(250);
			SetLEDState(YELLOW_LED, OFF);
			Wait(250);
		}
	}

	DisplayIntValue(0);
	SetLEDState(GREEN_LED, ON);
	Wait(500);
	ClearSevenSegmentDisplay();

	printf("System is ARMED. PB2 = motion event, PB3 = disarm.\n");
}

/*
 * activateAlarm
 * Intrusion detected: RED led on and BUZZER on. The alarm stays active
 * until the user disarms the system with PB3.
 */
void activateAlarm(void)
{
	SetLEDState(GREEN_LED, OFF);
	SetLEDState(RED_LED, ON);
	SetBuzzerState(BUZZER, ON);
}

/*
 * resetSystem
 * Disarms the system: all LEDs off, buzzer silenced, display cleared.
 * The system returns to the idle (disarmed) state.
 */
void resetSystem(void)
{
	SetLEDState(YELLOW_LED, OFF);
	SetLEDState(GREEN_LED, OFF);
	SetLEDState(RED_LED, OFF);
	SetBuzzerState(BUZZER, OFF);
	ClearSevenSegmentDisplay();

	printf("System DISARMED. PB1 = arm, PB4 = exit.\n");
}