Refactor and modularize code: separate configuration, data logging, and sensor handling into distinct header and source files; update documentation and improve readability.

Author: AdzCoder

include/config.h

@@ -0,0 +1,62 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#include <DFRobot_WT61PC.h>
+
+// ============================================================================
+// DEBUG CONFIGURATION
+// ============================================================================
+
+constexpr bool DEBUG_ENABLED = false;  // Set to true for serial debugging
+
+// ============================================================================
+// PIN DEFINITIONS
+// ============================================================================
+
+namespace Pins {
+constexpr int SD_CHIP_SELECT = 17;  // SD card CS pin
+constexpr int IMU_RX = 10;          // IMU RXD connection
+constexpr int IMU_TX = 11;          // IMU TXD connection
+constexpr int TEMPERATURE = A3;     // LM35DT temperature sensor
+constexpr int PRESSURE = A2;        // MPX4115A pressure sensor
+constexpr int BUZZER = 13;          // Landing detection buzzer
+}  // namespace Pins
+
+// ============================================================================
+// SYSTEM CONFIGURATION
+// ============================================================================
+
+namespace Config {
+constexpr unsigned long BUZZER_ARM_TIME = 15000;  // Time to arm buzzer (ms)
+constexpr unsigned long LOOP_DELAY = 200;         // Main loop delay (ms)
+constexpr unsigned long LANDING_CONFIRM_TIME =
+    2000;                                    // Landing confirmation time (ms)
+constexpr unsigned long IMU_TIMEOUT = 3000;  // IMU initialization timeout (ms)
+constexpr char DATA_FILENAME[] = "flight_data.txt";  // SD card data file
+constexpr float LANDING_ACC_MIN =
+    9.0;  // Minimum acceleration for landing (m/s²)
+constexpr float LANDING_ACC_MAX =
+    12.0;  // Maximum acceleration for landing (m/s²)
+constexpr int IMU_FREQUENCY = FREQUENCY_5HZ;  // Data output frequency
+}  // namespace Config
+
+// ============================================================================
+// SENSOR CALIBRATION CONSTANTS
+// ============================================================================
+
+namespace Calibration {
+constexpr float TEMP_VOLTAGE_REF =
+    5.0;  // Reference voltage for temperature sensor
+constexpr float TEMP_SCALE_FACTOR =
+    100.0;  // LM35DT conversion factor: 100°C per volt (from 10mV/°C)
+constexpr float PRESSURE_OFFSET = 0.095;    // MPX4115A offset
+constexpr float PRESSURE_SCALE = 0.000009;  // MPX4115A scale factor
+constexpr float PRESSURE_MIN = 15000.0;  // MPX4115A minimum valid pressure (Pa)
+constexpr float PRESSURE_MAX =
+    115000.0;  // MPX4115A maximum valid pressure (Pa)
+constexpr float ALTITUDE_EXPONENT = 1.0 / 5.257;  // Barometric formula exponent
+constexpr float REFERENCE_TEMP_K =
+    15.0 + 273.15;  // Reference temperature in Kelvin
+}  // namespace Calibration
+
+#endif  // CONFIG_H

include/data_logger.h

@@ -0,0 +1,32 @@
+#ifndef DATA_LOGGER_H
+#define DATA_LOGGER_H
+
+#include <SD.h>
+
+// ============================================================================
+// GLOBAL FILE OBJECT
+// ============================================================================
+
+extern File dataFile;  // SD card file handle for data logging
+
+// ============================================================================
+// FUNCTION DECLARATIONS
+// ============================================================================
+
+/**
+ * @brief Initialize SD card and create data file with headers
+ * @return true if successful, false otherwise
+ */
+bool initializeDataLogging();
+
+/**
+ * @brief Write sensor data to SD card in CSV format
+ */
+void logDataToSD();
+
+/**
+ * @brief Print sensor data to serial monitor for debugging
+ */
+void printDebugData();
+
+#endif  // DATA_LOGGER_H

include/sensors.h

@@ -0,0 +1,99 @@
+#ifndef SENSORS_H
+#define SENSORS_H
+
+#include <Arduino.h>
+#include <DFRobot_WT61PC.h>
+#include <SoftwareSerial.h>
+
+// ============================================================================
+// SENSOR DATA STRUCTURES
+// ============================================================================
+
+/**
+ * @brief Structure to hold all sensor readings
+ */
+struct SensorReadings {
+  unsigned long timestamp = 0;  // System uptime in milliseconds
+
+  // IMU Data
+  float accelX = 0.0;          // X-axis acceleration (m/s²)
+  float accelY = 0.0;          // Y-axis acceleration (m/s²)
+  float accelZ = 0.0;          // Z-axis acceleration (m/s²)
+  float accelMagnitude = 0.0;  // Total acceleration magnitude (m/s²)
+  float gyroX = 0.0;           // X-axis angular velocity (°/s)
+  float gyroY = 0.0;           // Y-axis angular velocity (°/s)
+  float gyroZ = 0.0;           // Z-axis angular velocity (°/s)
+
+  // Environmental Data
+  float temperature = 0.0;  // Temperature (°C)
+  float pressure = 0.0;     // Atmospheric pressure (Pa)
+  float altitude = 0.0;     // Calculated altitude (m)
+};
+
+/**
+ * @brief Structure to hold system state information
+ */
+struct SystemState {
+  float referencePressure =
+      0.0;  // Ground level pressure for altitude calculation (Pa)
+  bool sdCardReady = false;  // SD card initialization status
+  bool buzzerArmed = false;  // Landing detection buzzer status
+};
+
+// ============================================================================
+// GLOBAL SENSOR OBJECTS
+// ============================================================================
+
+extern SoftwareSerial imuSerial;  // Serial connection to IMU
+extern DFRobot_WT61PC imuSensor;  // IMU sensor object
+extern SensorReadings sensors;    // Current sensor readings
+extern SystemState systemState;   // Current system state
+
+// ============================================================================
+// FUNCTION DECLARATIONS
+// ============================================================================
+
+/**
+ * @brief Read temperature from LM35DT sensor
+ * @param pin Analog pin connected to temperature sensor
+ * @return Temperature in Celsius
+ */
+float readTemperature(int pin);
+
+/**
+ * @brief Read pressure from MPX4115A sensor
+ * @param pin Analog pin connected to pressure sensor
+ * @return Pressure in Pascals
+ */
+float readPressure(int pin);
+
+/**
+ * @brief Calculate altitude from pressure differential
+ * @param currentPressure Current atmospheric pressure (Pa)
+ * @param referencePressure Ground level pressure (Pa)
+ * @return Altitude in meters
+ */
+float calculateAltitude(float currentPressure, float referencePressure);
+
+/**
+ * @brief Update all sensor readings
+ */
+void updateSensorReadings();
+
+/**
+ * @brief Check for landing condition and control buzzer
+ */
+void checkLandingCondition();
+
+/**
+ * @brief Initialize IMU sensor
+ * @return true if successful, false otherwise
+ */
+bool initializeIMU();
+
+/**
+ * @brief Initialize reference pressure for altitude calculation
+ */
+void initializeReferencePressure();
+
+#endif  // SENSORS_H

src/data_logger.cpp

@@ -0,0 +1,109 @@
+#include "data_logger.h"
+
+#include <SD.h>
+
+#include "config.h"
+#include "sensors.h"
+
+// Global file object (actual definition)
+File dataFile;
+
+/**
+ * @brief Initialize SD card and create data file with headers
+ * @return true if successful, false otherwise
+ */
+bool initializeDataLogging() {
+  pinMode(Pins::SD_CHIP_SELECT, OUTPUT);
+
+  if (!SD.begin(Pins::SD_CHIP_SELECT)) {
+    if (DEBUG_ENABLED) {
+      Serial.println(F("ERROR: SD card initialization failed!"));
+    }
+    return false;
+  }
+
+  // Create/open data file and write headers
+  dataFile = SD.open(Config::DATA_FILENAME, FILE_WRITE);
+  if (dataFile) {
+    dataFile.println();
+    dataFile.println(F("=== ROCKET FLIGHT DATA LOG ==="));
+    dataFile.print(F("Timestamp(ms),Pressure(Pa),Temperature(C),Altitude(m),"));
+    dataFile.print(F("AccelX(m/s²),AccelY(m/s²),AccelZ(m/s²),AccelMag(m/s²),"));
+    dataFile.println(F("GyroX(°/s),GyroY(°/s),GyroZ(°/s)"));
+    dataFile.close();
+
+    if (DEBUG_ENABLED) {
+      Serial.println(F("✓ Data logging initialized"));
+    }
+    return true;
+  }
+
+  return false;
+}
+
+/**
+ * @brief Write sensor data to SD card
+ */
+void logDataToSD() {
+  if (!systemState.sdCardReady) return;
+
+  dataFile = SD.open(Config::DATA_FILENAME, FILE_WRITE);
+  if (dataFile) {
+    // Write data in CSV format
+    dataFile.print(sensors.timestamp);
+    dataFile.print(",");
+    dataFile.print(sensors.pressure, 2);
+    dataFile.print(",");
+    dataFile.print(sensors.temperature, 2);
+    dataFile.print(",");
+    dataFile.print(sensors.altitude, 2);
+    dataFile.print(",");
+    dataFile.print(sensors.accelX, 3);
+    dataFile.print(",");
+    dataFile.print(sensors.accelY, 3);
+    dataFile.print(",");
+    dataFile.print(sensors.accelZ, 3);
+    dataFile.print(",");
+    dataFile.print(sensors.accelMagnitude, 3);
+    dataFile.print(",");
+    dataFile.print(sensors.gyroX, 3);
+    dataFile.print(",");
+    dataFile.print(sensors.gyroY, 3);
+    dataFile.print(",");
+    dataFile.println(sensors.gyroZ, 3);
+    dataFile.close();
+  } else if (DEBUG_ENABLED) {
+    Serial.println(F("ERROR: Failed to write to SD card"));
+  }
+}
+
+/**
+ * @brief Print sensor data to serial monitor for debugging
+ */
+void printDebugData() {
+  if (!DEBUG_ENABLED) return;
+
+  Serial.print(F("Time: "));
+  Serial.print(sensors.timestamp);
+  Serial.print(F(" | P: "));
+  Serial.print(sensors.pressure, 1);
+  Serial.print(F(" | T: "));
+  Serial.print(sensors.temperature, 1);
+  Serial.print(F(" | Alt: "));
+  Serial.print(sensors.altitude, 1);
+  Serial.print(F(" | Acc: ["));
+  Serial.print(sensors.accelX, 2);
+  Serial.print(F(", "));
+  Serial.print(sensors.accelY, 2);
+  Serial.print(F(", "));
+  Serial.print(sensors.accelZ, 2);
+  Serial.print(F("] |Mag: "));
+  Serial.print(sensors.accelMagnitude, 2);
+  Serial.print(F(" | Gyro: ["));
+  Serial.print(sensors.gyroX, 1);
+  Serial.print(F(", "));
+  Serial.print(sensors.gyroY, 1);
+  Serial.print(F(", "));
+  Serial.print(sensors.gyroZ, 1);
+  Serial.println(F("]"));
+}