/**
* Name: Ash Zahabiuon
* Date: 8/5/2024
* Assignment: Lab 5
* Youtube: https://youtu.be/jHYgZ0sjfCg
*
/**
* This program initializes UART for serial communication, sets up GPIO for
* button input, configures ADC to read analog values from a sensor, and
* transmits the ADC values over UART. It also detects button presses to
* send a specific fire command over UART when the button is pressed.
* The ADC values are constrained to 8-bit (0-255) for transmission.
*
* - UART is set up for 9600 baud communication.
* - GPIO pin P1.3 is configured as an input with a pull-up resistor for button detection.
* - ADC reads the value from channel 4 (P1.4).
* - ADC values are converted to 8-bit and transmitted over UART.
* - Top Gun plays using the controller on Com3.
*/


#include <msp430.h>

void initUART() {
    P1SEL |= BIT1 + BIT2;    // P1.1 = RXD, P1.2=TXD
    P1SEL2 |= BIT1 + BIT2;   // P1.1 = RXD, P1.2=TXD
    UCA0CTL1 |= UCSSEL_2;    // SMCLK
    UCA0BR0 = 104;           // 1MHz 9600
    UCA0BR1 = 0;             // 1MHz 9600
    UCA0MCTL = UCBRS0;       // Modulation UCBRSx = 1
    UCA0CTL1 &= ~UCSWRST;    // Initialize USCI state machine
    IE2 |= UCA0RXIE;         // Enable USCI_A0 RX interrupt
}

void UART_Write(unsigned char data) {
    while (!(IFG2 & UCA0TXIFG)); // Wait for the TX buffer to be ready
    UCA0TXBUF = data;            // Send data
}

void initGPIO() {
    P1DIR &= ~BIT3;   // Set P1.3 as input
    P1REN |= BIT3;    // Enable pull-up resistor on P1.3
    P1OUT |= BIT3;    // Set pull-up mode
}

int isButtonPressed() {
    return !(P1IN & BIT3);  // Return 1 if button is pressed
}

void initADC() {
    ADC10CTL1 = INCH_4;                    // Channel 4 (P1.4)
    ADC10AE0 |= BIT4;                      // Enable ADC input on P1.4
    ADC10CTL0 = SREF_0 + ADC10SHT_2 + ADC10ON; // Vcc & Vss as reference, 16 x ADC10CLKs, ADC ON
}

unsigned int readADC() {
    ADC10CTL0 |= ENC + ADC10SC;            // Sampling and conversion start
    while (ADC10CTL1 & ADC10BUSY);         // Wait for conversion to complete
    return ADC10MEM;                       // Return conversion result
}

int debounceButton() {
    if (isButtonPressed()) {
        __delay_cycles(1000); // Delay to debounce
        if (isButtonPressed()) {
            return 1;
        }
    }
    return 0;
}

void main(void) {
    WDTCTL = WDTPW + WDTHOLD;    // Stop WDT
    initUART();
    initGPIO();
    initADC();

    int buttonPressed = 0;

    while (1) {
        unsigned int adcValue = readADC();
        if (adcValue > 255) adcValue = 254; // Handle 10-bit to 8-bit conversion
        UART_Write(adcValue);               // Send ADC value

        // Fire command in a separate loop with debounce
        if (debounceButton()) {
            if (!buttonPressed) {
                UART_Write(255);           // Send fire command
                buttonPressed = 1;         // Mark button as pressed
            }
        } else {
            buttonPressed = 0;             // Reset button press state when button is released
        }
    }
}