/*
12 hour clock
12, 1 hour leds
12, 5 min leds
Start clock at 12 noon or 12 midnight

Hardware: Atmega8 with 8mhz crystal

This is working well and pretty easy to undertand how the code works.

Sketch uses 810 bytes (2%) of program storage space. Maximum is 32256 bytes.
Global variables use 54 bytes (2%) of dynamic memory, leaving 1994 bytes for local variables. Maximum is 2048 bytes.

*** USE THIS FINISHED VERSION ***
*** IF NOT USING RGB OR TIME SET ***
*/

#define F_CPU 8000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

// --- Hour LED Pins (PORTD: PD2–PD5) ---
#define P0 PD2
#define P1 PD3
#define P2 PD4
#define P3 PD5

// --- Minute LED Pins (PD6, PD7, PB0, PB1) ---
#define Q0 PD6
#define Q1 PD7
#define Q2 PB0
#define Q3 PB1

// --- LED Mappings: 12 LEDs per group, high_pin, low_pin ---
const uint8_t hour_leds[12][2] = {
  {P0, P1}, {P1, P0}, {P0, P2}, {P2, P0},
  {P0, P3}, {P3, P0}, {P1, P2}, {P2, P1},
  {P1, P3}, {P3, P1}, {P2, P3}, {P3, P2}
};

const uint8_t minute_leds[12][2] = {
  {Q0, Q1}, {Q1, Q0}, {Q0, Q2}, {Q2, Q0},
  {Q0, Q3}, {Q3, Q0}, {Q1, Q2}, {Q2, Q1},
  {Q1, Q3}, {Q3, Q1}, {Q2, Q3}, {Q3, Q2}
};

volatile uint32_t seconds = 0;
uint8_t hour = 0;
uint8_t five_minute_index = 0;

// === Timer1 Initialization ===
void timer1_init() {
  TCCR1A = 0;               // Normal mode
  TCCR1B = (1 << WGM12);    // CTC mode 4, OCR1A = TOP
  TCCR1B |= (1 << CS12);    // Prescaler 256
  OCR1A = 31250;            // Compare match at 1 second
  TIMSK1 |= (1 << OCIE1A);  // Compare match interrupt
  sei();                    // Enable global interrupts
}

// === Reset all pins to Hi-Z ===
void reset_hour_pins() {
  // Set as Inputs
  DDRD &= ~((1 << P0) | (1 << P1) | (1 << P2) | (1 << P3));
  // Set as 0, no pullup
  PORTD &= ~((1 << P0) | (1 << P1) | (1 << P2) | (1 << P3));
}

void reset_minute_pins() {
  DDRD &= ~((1 << Q0) | (1 << Q1));
  PORTD &= ~((1 << Q0) | (1 << Q1));

  DDRB &= ~((1 << Q2) | (1 << Q3));
  PORTB &= ~((1 << Q2) | (1 << Q3));
}

// === Light 1 of 12 Hour LEDs ===
void light_hour_led(uint8_t index) {
  reset_hour_pins(); // All pins Hi-Z

  uint8_t high = hour_leds[index][0];
  uint8_t low  = hour_leds[index][1];

  DDRD |= (1 << high) | (1 << low);
  PORTD |= (1 << high);
  PORTD &= ~(1 << low);
}

// === Light 1 of 12 Minute LEDs ===
void light_minute_led(uint8_t index) {
  reset_minute_pins(); // All pins Hi-Z

  uint8_t high = minute_leds[index][0];
  uint8_t low  = minute_leds[index][1];

  // === Set HIGH pin ===
  if (high == PB0 || high == PB1) {
    DDRB |= (1 << high);
    PORTB |= (1 << high);
  }
  else {
    DDRD |= (1 << high);
    PORTD |= (1 << high);
  }

  // === Set LOW pin ===
  if (low == PB0 || low == PB1) {
    DDRB |= (1 << low);
    PORTB &= ~(1 << low);
  }
  else {
    DDRD |= (1 << low);
    PORTD &= ~(1 << low);
  }
}

// === Timer ISR: Fire every second ===
ISR(TIMER1_COMPA_vect) {
  seconds++;

  // Every hour
  if (seconds % 60 == 0) { // 3600, use 60 for testing
    hour++;
    if (hour >= 12) hour = 0;
  }

  // Every 5 minutes
  if (seconds % 5 == 0) { // 300, use 5 for testing
    five_minute_index++;
    if (five_minute_index >= 12) five_minute_index = 0;
  }
}

// === Main Loop ===
int main(void) {
  timer1_init();
  reset_hour_pins();
  reset_minute_pins();

  while (1) {
    light_hour_led(hour);
    _delay_ms(3);

    light_minute_led(five_minute_index);
    _delay_ms(3);
  }
}