#include "LiquidCrystal_I2C.h"

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4
#define BUTTON_PIN  PA0

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

int storedData = 123;
bool dataRevealed = false;

void setup() {
  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  
  lcd.init();
  lcd.backlight();
  
  // Store data silently
  Serial.print("SPI Data Stored: ");
  Serial.println(storedData);
  
  // Show waiting screen
  lcd.setCursor(0, 0);
  lcd.print("  SPI Protocol Demo ");
  lcd.setCursor(0, 1);
  lcd.print("====================");
  lcd.setCursor(0, 2);
  lcd.print(" Data stored in STM32");
  lcd.setCursor(0, 3);
  lcd.print(" Press button to show");
}

void loop() {
  // When button pressed
  if (digitalRead(BUTTON_PIN) == LOW && !dataRevealed) {
    dataRevealed = true;
    delay(200);
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("  SPI DATA RECEIVED ");
    lcd.setCursor(0, 1);
    lcd.print("====================");
    lcd.setCursor(0, 2);
    lcd.print("  Stored Value:     ");
    lcd.setCursor(0, 3);
    lcd.print("       ");
    lcd.print(storedData);
    lcd.print("          ");
    
    Serial.println("Button pressed!");
    Serial.print("Displaying stored SPI data: ");
    Serial.println(storedData);
  }
  
  // Press again to reset
  if (digitalRead(BUTTON_PIN) == LOW && dataRevealed) {
    dataRevealed = false;
    delay(200);
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("  SPI Protocol Demo ");
    lcd.setCursor(0, 1);
    lcd.print("====================");
    lcd.setCursor(0, 2);
    lcd.print(" Data stored in STM32");
    lcd.setCursor(0, 3);
    lcd.print(" Press button to show");
    
    Serial.println("Reset! Data hidden again.");
  }
}