/*
 * Project: Single Button Timer for PIC12F508 using HI-TECH C
 * Compiler: HI-TECH C for PIC10/12/16 (v9.70 or similar)
 * Environment: MPLAB IDE v8.xx
 * MCU: PIC12F508
 * Oscillator: Internal 4MHz
 */
 
#include <htc.h>
 
// Configuration fuses are set using __CONFIG() macro in HI-TECH C.
// __CONFIG(CPDIS & WDTDIS & IntRC & MCLRDIS); // Example config line
 
// Define the pins using the header file's standard register names
#define RELAY_PIN  GP2
#define BUTTON_PIN GP3
#define LED_30MIN  GP0
#define LED_45MIN  GP1
#define LED_60MIN  GP4
 
// Time definitions in minutes
#define TIME_30M 30
#define TIME_45M 45
#define TIME_60M 60
 
// Global variables
// Use 'volatile' for variables changed within a timing loop
volatile unsigned char timer_options[] = {TIME_30M, TIME_45M, TIME_60M};
volatile unsigned char current_time_index = 0;
volatile unsigned long time_remaining_seconds = 0;
volatile unsigned char button_press_counter = 0;
volatile unsigned char is_pressed = 0;
volatile unsigned char timer0_tick_count = 0;
volatile unsigned char timer_running = 0;
 
void InitMCU(void) {
    // Configure I/O pins: GP3 input, others output
    TRIS = 0b00001000; // GP3 is input (1), others are outputs (0)
 
    // Set initial output states
    GPIO = 0x00;
    RELAY_PIN = 0;
 
    // OPTION register configuration for Timer0 polling:
    // T0CS=0 (internal clock Fosc/4)
    // PSA=0 (prescaler assigned to Timer0)
    // PS2:PS0 = 111 (1:256 prescaler)
    // GPPU=1 (Enable weak pull-ups on GPIO, assuming MCLRE is off)
    OPTION = 0b01000111;
}
 
// Function to update the indicator LEDs
void UpdateLEDs(void) {
    LED_30MIN = 0;
    LED_45MIN = 0;
    LED_60MIN = 0;
 
    if (current_time_index == 0)      LED_30MIN = 1;
    else if (current_time_index == 1) LED_45MIN = 1;
    else if (current_time_index == 2) LED_60MIN = 1;
}
 
// Main loop function to handle the timer overflow check
void TimerService(void) {
    // Check if Timer0 overflowed (T0IF flag in INTCON register)
    if (INTCONbits.T0IF) {
        INTCONbits.T0IF = 0; // Clear the flag
        // TMR0 register does not need a full reload for this approach
 
        timer0_tick_count++;
 
        // We need about 61 overflows for 1 second (~16.4ms per tick)
        if (timer0_tick_count >= 61) {
            timer0_tick_count = 0;
            // 1 second has passed
            if (timer_running && time_remaining_seconds > 0) {
                time_remaining_seconds--;
                if (time_remaining_seconds == 0) {
                    // Timer finished, turn off relay
                    RELAY_PIN = 0;
                    timer_running = 0;
                }
            }
        }
    }
}
 
// Function to handle button presses and state
void ButtonService(void) {
    // Simple Debounce and Press Detection
    if (BUTTON_PIN == 0) { // Button is pressed (LOW)
        if (!is_pressed) {
            is_pressed = 1;
            button_press_counter = 0; // Start counting duration
        } else {
            // Count how long it's pressed (using the 16.4ms ticks)
            if (button_press_counter < 255) {
               button_press_counter++;
            }
        }
    } else { // Button is released (HIGH)
        if (is_pressed) {
            is_pressed = 0;
 
            // Determine if short or long press
            // Threshold for long press is roughly 1 second (approx 61 ticks)
            if (button_press_counter < 61) { 
                // Handle Short Press: Start/Stop the timer
                if (!timer_running) {
                    // Start time is minutes * 60 seconds
                    time_remaining_seconds = (unsigned long)timer_options[current_time_index] * 60;
                    RELAY_PIN = 1; // Turn relay ON
                    timer_running = 1;
                } else {
                    // Stop the timer if running
                    time_remaining_seconds = 0;
                    RELAY_PIN = 0;
                    timer_running = 0;
                }
            } else {
                // Handle Long Press: Change the timer function
                if (!timer_running) { // Only change time if not running
                    current_time_index++;
                    if (current_time_index >= 3) {
                        current_time_index = 0;
                    }
                    UpdateLEDs();
                }
            }
            button_press_counter = 0; // Reset counter
        }
    }
}
 
void main(void) {
    InitMCU();
    UpdateLEDs(); // Set the initial LED state (30 min)
 
    while (1) {
        TimerService();
        ButtonService();
    }
}
 

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