/*
 * ============================================================
 *  16×2 LCD Display with I2C Module (PCF8574T) — Sample Sketch
 *  Tishvi Electronics | guide.tishvi.com
 * ============================================================
 *  Wiring (I2C — only 4 wires!):
 *    LCD Module GND → Arduino GND
 *    LCD Module VCC → Arduino 5V
 *    LCD Module SDA → Arduino A4
 *    LCD Module SCL → Arduino A5
 *
 *  I2C Address: 0x27  (PCF8574T default)
 *               0x3F  (PCF8574AT — try this if 0x27 does not work)
 *
 *  Library required — install via Arduino IDE Library Manager:
 *    LiquidCrystal_I2C  (search: "LiquidCrystal I2C" by Frank de Brabander)
 *
 *  What this sketch does:
 *    1. Initialises the LCD and turns on the backlight
 *    2. Displays a welcome message on two rows
 *    3. After 2 seconds, starts a live uptime counter (HH:MM:SS)
 *    4. Demonstrates cursor control and text clearing
 * ============================================================
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// ── Display Configuration ────────────────────────────────────
// LiquidCrystal_I2C(i2c_address, columns, rows)
// Try 0x3F if your display stays blank with 0x27
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);

  // ── Initialise LCD ──────────────────────────────────────
  lcd.init();
  lcd.backlight();          // Turn on backlight

  Serial.println("16x2 LCD I2C — Tishvi Sample Sketch");
  Serial.println("LCD initialised.");

  // ── Welcome Screen ──────────────────────────────────────
  // Row 0 (top row)
  lcd.setCursor(0, 0);
  lcd.print("  TISHVI  DOCS  ");

  // Row 1 (bottom row)
  lcd.setCursor(0, 1);
  lcd.print(" LCD I2C Ready! ");

  delay(2500);   // Show welcome for 2.5 seconds
  lcd.clear();
}

void loop() {
  // ── Live Uptime Counter ─────────────────────────────────
  unsigned long totalSec = millis() / 1000;
  unsigned int  hours    = totalSec / 3600;
  unsigned int  minutes  = (totalSec % 3600) / 60;
  unsigned int  seconds  = totalSec % 60;

  // ── Row 0: Label ───────────────────────────────────────
  lcd.setCursor(0, 0);
  lcd.print("Uptime:         ");

  // ── Row 1: HH:MM:SS ────────────────────────────────────
  lcd.setCursor(0, 1);

  // Zero-pad each component to 2 digits
  if (hours   < 10) lcd.print("0");
  lcd.print(hours);
  lcd.print(":");
  if (minutes < 10) lcd.print("0");
  lcd.print(minutes);
  lcd.print(":");
  if (seconds < 10) lcd.print("0");
  lcd.print(seconds);
  lcd.print("  Tishvi ");

  // Also log to Serial Monitor
  Serial.print("Uptime: ");
  if (hours < 10) Serial.print("0");
  Serial.print(hours);
  Serial.print(":");
  if (minutes < 10) Serial.print("0");
  Serial.print(minutes);
  Serial.print(":");
  if (seconds < 10) Serial.print("0");
  Serial.println(seconds);

  delay(1000);   // Update every second
}