/*
  Arduino Mega code to read a slide potentiometer (pot1), map its value to 0-99, display the two-digit 
  number on two 7-segment displays (sevseg1, sevseg2) driven via two 74HC595 shift registers (sr1, sr2),
  and to control three LEDs (led1, led2, led3) so that:
    •  0 <= value <= 33   --> only led1 lights up.
    • 34 <= value <= 66   --> led1 and led2 light up.
    • 67 <= value <= 99   --> led1, led2, led3 light up.
  
  Each state is maintained for 2 seconds.
*/

#include <Arduino.h>
#include <Servo.h>  // Included as allowed, though not used here.

// Pin definitions for potentiometer.
const int potPin = A0;  

// LED pins.
const int led1Pin = 22;
const int led2Pin = 23;
const int led3Pin = 24;

// 74HC595 pins for sevseg1 (tens digit)
const int sr1DataPin = 2;
const int sr1ClockPin = 3;
const int sr1LatchPin = 4;

// 74HC595 pins for sevseg2 (ones digit)
const int sr2DataPin = 5;
const int sr2ClockPin = 6;
const int sr2LatchPin = 7;

// Seven-segment digit patterns for common anode (active LOW):
// Each pattern is organized as: Bit0=A, Bit1=B, Bit2=C, Bit3=D, Bit4=E, Bit5=F, Bit6=G, Bit7=DP.
const byte sevenSegDigits[10] = {
  0xC0, // 0 : 0b11000000, segments A-F on, G off, DP off.
  0xF9, // 1 : 0b11111001, only segments B and C on.
  0xA4, // 2 : 0b10100100
  0xB0, // 3 : 0b10110000
  0x99, // 4 : 0b10011001
  0x92, // 5 : 0b10010010
  0x82, // 6 : 0b10000010
  0xF8, // 7 : 0b11111000
  0x80, // 8 : 0b10000000
  0x90  // 9 : 0b10010000
};

void setup() {
  // Initialize serial (optional for debugging)
  Serial.begin(9600);
  
  // Set LED pins as OUTPUT.
  pinMode(led1Pin, OUTPUT);
  pinMode(led2Pin, OUTPUT);
  pinMode(led3Pin, OUTPUT);
  
  // Turn off LEDs initially.
  digitalWrite(led1Pin, LOW);
  digitalWrite(led2Pin, LOW);
  digitalWrite(led3Pin, LOW);
  
  // Set shift register pins as OUTPUT.
  pinMode(sr1DataPin, OUTPUT);
  pinMode(sr1ClockPin, OUTPUT);
  pinMode(sr1LatchPin, OUTPUT);
  
  pinMode(sr2DataPin, OUTPUT);
  pinMode(sr2ClockPin, OUTPUT);
  pinMode(sr2LatchPin, OUTPUT);
  
  // Initialization: Set both 7-seg displays to "00".
  updateSevenSegDisplay(0, 0);
}

void loop() {
  // Read the analog value from pot1.
  int analogVal = analogRead(potPin);
  
  // Map the potentiometer value (0-1023) to a two-digit value (0-99).
  int mappedVal = map(analogVal, 0, 1023, 0, 99);
  
  // Calculate tens and ones.
  int tens = mappedVal / 10;
  int ones = mappedVal % 10;
  
  // Update seven-segment displays.
  updateSevenSegDisplay(tens, ones);
  
  // Update the LED status based on mapped value.
  updateLEDs(mappedVal);
  
  // For debugging, print the values.
  Serial.print("Analog: ");
  Serial.print(analogVal);
  Serial.print(" Mapped: ");
  Serial.println(mappedVal);
  
  // Maintain the current state for 2 seconds.
  delay(2000);
}

// Function that sends the 7-segment code to each display by using the appropriate 74HC595 shift register.
void updateSevenSegDisplay(int tens, int ones) {
  // Update sevseg1 (tens digit) via sr1.
  byte tensPattern = sevenSegDigits[tens];
  digitalWrite(sr1LatchPin, LOW);
  // Use shiftOut to send data to the shift register.
  shiftOut(sr1DataPin, sr1ClockPin, MSBFIRST, tensPattern);
  digitalWrite(sr1LatchPin, HIGH);   // Latch the data
  
  // Update sevseg2 (ones digit) via sr2.
  byte onesPattern = sevenSegDigits[ones];
  digitalWrite(sr2LatchPin, LOW);
  shiftOut(sr2DataPin, sr2ClockPin, MSBFIRST, onesPattern);
  digitalWrite(sr2LatchPin, HIGH);
}

// Function to update the LED states according to the rules.
void updateLEDs(int value) {
  if (value >= 0 && value <= 33) {
    digitalWrite(led1Pin, HIGH); // ON
    digitalWrite(led2Pin, LOW);  // OFF
    digitalWrite(led3Pin, LOW);  // OFF
  }
  else if (value >= 34 && value <= 66) {
    digitalWrite(led1Pin, HIGH);
    digitalWrite(led2Pin, HIGH);
    digitalWrite(led3Pin, LOW);
  }
  else if (value >= 67 && value <= 99) {
    digitalWrite(led1Pin, HIGH);
    digitalWrite(led2Pin, HIGH);
    digitalWrite(led3Pin, HIGH);
  }
}