/*
 * Arduino Counter System with 7-Segment Displays, Bar Graph, and Alternating LEDs
 * 
 * This system:
 * - Displays a number from 00-99 on two 7-segment displays
 * - Shows the number's magnitude on a bar graph (tens digit + 1 segments)
 * - Alternates two LEDs every 2 seconds
 * - Increments the number every 2 seconds
 */

// Define pins for Shift Register 1 (controlling tens display)
const int sr1_dataPin = 10;   // DS pin
const int sr1_clockPin = 11;  // SHCP pin
const int sr1_latchPin = 12;  // STCP pin

// Define pins for Shift Register 2 (controlling units display)
const int sr2_dataPin = 13;   // DS pin
const int sr2_clockPin = 14;  // SHCP pin
const int sr2_latchPin = 15;  // STCP pin

// Define pins for LED Bar Graph (10 segments)
const int barGraphPins[] = {20, 21, 22, 23, 24, 25, 26, 27, 28, 29};

// Define pins for individual LEDs
const int led1Pin = 30;
const int led2Pin = 31;

// 7-segment display digit patterns for common anode displays
// Bits: ABCDEFGDP (segments are ON when bit is LOW)
const byte digitPatterns[] = {
  0b11000000, // 0
  0b11111001, // 1
  0b10100100, // 2
  0b10110000, // 3
  0b10011001, // 4
  0b10010010, // 5
  0b10000010, // 6
  0b11111000, // 7
  0b10000000, // 8
  0b10010000  // 9
};

// Variables to track system state
int currentNumber = 0;     // Current displayed number (0-99)
bool ledState = false;     // LED toggle state
unsigned long lastUpdateTime = 0;  // For timing the 2-second intervals

void setup() {
  // Initialize shift register pins
  pinMode(sr1_dataPin, OUTPUT);
  pinMode(sr1_clockPin, OUTPUT);
  pinMode(sr1_latchPin, OUTPUT);
  pinMode(sr2_dataPin, OUTPUT);
  pinMode(sr2_clockPin, OUTPUT);
  pinMode(sr2_latchPin, OUTPUT);
  
  // Initialize LED bar graph pins
  for (int i = 0; i < 10; i++) {
    pinMode(barGraphPins[i], OUTPUT);
  }
  
  // Initialize individual LED pins
  pinMode(led1Pin, OUTPUT);
  pinMode(led2Pin, OUTPUT);
  
  // Set initial state
  updateDisplay();
  updateBarGraph();
  digitalWrite(led1Pin, LOW);
  digitalWrite(led2Pin, LOW);
}

void loop() {
  // Check if 2 seconds have passed
  unsigned long currentTime = millis();
  if (currentTime - lastUpdateTime >= 2000) {
    // Increment counter
    currentNumber = (currentNumber + 1) % 100;
    
    // Update displays and LEDs
    updateDisplay();
    updateBarGraph();
    updateLEDs();
    
    // Reset timer
    lastUpdateTime = currentTime;
  }
}

// Function to update the 7-segment displays
void updateDisplay() {
  int tens = currentNumber / 10;
  int ones = currentNumber % 10;
  
  // Update tens digit on first display
  digitalWrite(sr1_latchPin, LOW);
  shiftOut(sr1_dataPin, sr1_clockPin, MSBFIRST, digitPatterns[tens]);
  digitalWrite(sr1_latchPin, HIGH);
  
  // Update ones digit on second display
  digitalWrite(sr2_latchPin, LOW);
  shiftOut(sr2_dataPin, sr2_clockPin, MSBFIRST, digitPatterns[ones]);
  digitalWrite(sr2_latchPin, HIGH);
}

// Function to update the LED bar graph
void updateBarGraph() {
  int segmentsToLight = (currentNumber / 10) + 1;  // tens digit + 1
  
  // Turn on/off appropriate number of segments
  for (int i = 0; i < 10; i++) {
    if (i < segmentsToLight) {
      digitalWrite(barGraphPins[i], HIGH); // Turn segment on
    } else {
      digitalWrite(barGraphPins[i], LOW);  // Turn segment off
    }
  }
}

// Function to toggle the LEDs
void updateLEDs() {
  ledState = !ledState;  // Toggle state
  digitalWrite(led1Pin, ledState);     // LED1 follows state
  digitalWrite(led2Pin, !ledState);    // LED2 does opposite
}