#include <Wire.h>
#include <SD.h>

#define LOG_FILE_NAME "altitude.log"
#define LOG_INTERVAL 300 // Log interval in milliseconds
Adafruit_BMP280 bmp; // Create BMP280 object

File logFile; // Create log file object
float maxAltitude = 0.0; // Initialize maximum altitude variable

void setup() {
    Serial.begin(9600); // Start serial communication
    if (!bmp.begin(0x76)) { // Initialize BMP280 with I2C address 0x76
    Serial.println("Could not find a valid BMP280 sensor, check wiring!");
    }
    while (1);
      }
      if (!SD.begin(10)) { // Initialize microSD card with pin 10
      Serial.println("Could not initialize SD card, check wiring!");
      }
    logFile = SD.open(LOG_FILE_NAME, FILE_WRITE); // Open log file for writing
    logFile.println("Time,Altitude"); // Write header to log file
    logFile.close();
  }

void loop() {
  static unsigned long lastLogTime = 0; // Initialize last log time variable
  unsigned long currentTime = millis(); // Get current time in milliseconds
  float temperature = bmp.readTemperature(); // Read temperature in Celsius
  float pressure = bmp.readPressure() / 100.0; // Read pressure in hPa
  float altitude = bmp.readAltitude(1012.7); // Read altitude in meters relative to sea level
  // Update maximum altitude
  if (altitude > maxAltitude) {
  maxAltitude = altitude;
  }
  
  // Log altitude every 0.3 seconds
  if (currentTime - lastLogTime >= LOG_INTERVAL) {
  logFile = SD.open(LOG_FILE_NAME, FILE_WRITE); // Open log file for writing
  logFile.print(currentTime / 1000.0); // Write time in seconds
  logFile.print(",");
  logFile.println(altitude); // Write altitude
  logFile.close();
  lastLogTime = currentTime; // Update last log time
  }
  delay(100); // Wait for 0.1 second before reading again
}