/**
* Name: Ash Zahabiuon
* Date: 7/17/2024
* Assignment: Lab 4
* Youtube: https://youtu.be/AsoatPVCDps
*
/**
* This program:
* When ran, pressing the button cycles through different states:
* 1. System armed: GREEN LED on.
* 2. Tripwire triggered: RED LED on, alarm sounds for 15 seconds or until reset.
* 3. System disarmed: GREEN LED off, RED LED off, alarm off.
* Pressing the button:
* - Arms the system if disarmed.
* - Disarms the system if armed.
* - Resets the alarm if it is active.
*/


#include <msp430.h>
#include <stdbool.h>

// Define button and LED pins
#define ARM_BUTTON_PIN BIT3 // P1.3
#define RED_LED_PIN BIT0    // P1.0
#define GREEN_LED_PIN BIT6  // P1.6

void initGPIO() {
    // Stop watchdog timer
    WDTCTL = WDTPW | WDTHOLD;

    // Set the buzzer pin (P2.2) as output
    P2DIR |= BIT2;
    P2SEL |= BIT2; // Select Timer_A output

    // Set the trigger pin (P2.1) as output and echo pin (P1.1) as input
    P2DIR |= BIT1; // TRIG
    P1DIR &= ~BIT1; // ECHO

    // Set the arm button pin (P1.3) as input
    P1DIR &= ~ARM_BUTTON_PIN;
    P1REN |= ARM_BUTTON_PIN; // Enable pull-up/down resistor
    P1OUT |= ARM_BUTTON_PIN; // Set pull-up resistor

    // Set the LED pins as output
    P1DIR |= RED_LED_PIN;    // Set P1.0 (RED LED) to output direction
    P1DIR |= GREEN_LED_PIN;  // Set P1.6 (GREEN LED) to output direction

    // Initialize LEDs to off
    P1OUT &= ~RED_LED_PIN;
    P1OUT &= ~GREEN_LED_PIN;
}

void initTimer() {
    // Configure Timer_A for PWM on P2.2 (TA1.1)
    TA1CCR0 = 1000 - 1;           // PWM Period
    TA1CCTL1 = OUTMOD_7;          // CCR1 reset/set
    TA1CCR1 = 500;                // CCR1 PWM duty cycle
    TA1CTL = TASSEL_2 + MC_1;     // SMCLK, up mode

    // Configure Timer_A for ultrasonic sensor
    TA0CCTL0 = CCIE;            // Enable interrupt
    TA0CCR0 = 50000;            // Set timer count
    TA0CTL = TASSEL_2 + MC_1;   // SMCLK, up mode
}

void setPWMDutyCycle(unsigned int dutyCycle) {
    TA1CCR1 = dutyCycle; // Set PWM duty cycle
}

void triggerUltrasonic() {
    P2OUT |= BIT1; // Set TRIG pin high
    __delay_cycles(10); // Wait for 10us
    P2OUT &= ~BIT1; // Set TRIG pin low
}

unsigned int measureDistance() {
    unsigned int duration;

    // Send trigger pulse
    triggerUltrasonic();

    // Wait for echo start
    while (!(P1IN & BIT1));

    // Measure echo duration
    TA0CTL |= TACLR; // Clear timer
    TA0CTL |= MC_2; // Continuous mode
    while (P1IN & BIT1);
    duration = TA0R; // Read timer value
    TA0CTL &= ~MC_2; // Stop timer

    // Calculate distance in cm (assuming 1 MHz clock)
    unsigned int distance = (duration / 58);
    return distance;
}

bool isButtonPressed() {
    if (!(P1IN & ARM_BUTTON_PIN)) { // If button is pressed
        __delay_cycles(50000); // Debounce delay
        if (!(P1IN & ARM_BUTTON_PIN)) { // If button is still pressed
            return true;
        }
    }
    return false;
}

void delaySeconds(unsigned int seconds) {
    while (seconds--) {
        __delay_cycles(1000000); // Assuming 1 MHz clock, 1 second delay
        if (isButtonPressed()) {
            break;
        }
    }
}

int main(void) {
    initGPIO(); // Initialize GPIO
    initTimer(); // Initialize Timer

    bool armed = false;
    unsigned int armedDistance = 0;
    bool buttonPreviouslyPressed = false;
    bool alarmActive = false;

    while (1) {
        if (isButtonPressed()) {
            if (!buttonPreviouslyPressed) {
                armed = !armed;
                if (armed) {
                    // Measure initial distance when armed
                    armedDistance = measureDistance();
                    P1OUT |= GREEN_LED_PIN; // Turn on GREEN LED when armed
                } else {
                    alarmActive = false;
                    setPWMDutyCycle(0); // Turn off the buzzer
                    P1OUT &= ~GREEN_LED_PIN; // Turn off GREEN LED when disarmed
                }
                buttonPreviouslyPressed = true;
            }
        } else {
            buttonPreviouslyPressed = false;
        }

        if (armed && !alarmActive) {
            unsigned int currentDistance = measureDistance();
            if (abs(currentDistance - armedDistance) > 10) { // Significant change detected
                setPWMDutyCycle(750); // Sound the alarm
                P1OUT |= RED_LED_PIN; // Turn on RED LED when alarm is active
                alarmActive = true;
                delaySeconds(15); // Keep the buzzer on for 15 seconds or until reset
                alarmActive = false;
                setPWMDutyCycle(0); // Turn off the buzzer
                P1OUT &= ~RED_LED_PIN; // Turn off RED LED after alarm
            }
        } else {
            setPWMDutyCycle(0); // Turn off the buzzer when disarmed or alarm is not active
        }

        __delay_cycles(100000); // Delay between measurements
    }
}