Review of Arduino code

data_acquisition.cpp

#include <SD.h>
#define POTENTIOMETER_PIN A0

int potValue;
int previousPotValue;
bool buttonState = HIGH;
bool previousButtonState = HIGH;
bool recording = false;       // Flag to indicate whether data recording is active
unsigned long startTime = 0;  // Variable to store the start time
int rateOfChange;
const int buttonPin = 7;  // Button input pin
int data[100];            // Array to store data
int dataIndex = 0;        // Index of the next element in the array

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

  // Set button pin as input with pull-up resistor
  pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
  // Read potentiometer value
  potValue = analogRead(POTENTIOMETER_PIN);

  // Save current value
  previousPotValue = potValue;

  // Calculate rate of change
  rateOfChange = potValue - previousPotValue;

  //Current button pin value
  buttonState = digitalRead(buttonPin);

  // Save current state
  previousButtonState = buttonState;

  // Check if the button is pressed and has changed state
  if (buttonState == LOW && previousButtonState == HIGH) {
    recording = !recording;  // Toggle recording state
    if (recording) {
      startTime = millis();  // Record the start time
    }
    delay(500);  // Debounce delay
  }

  if (recording) {
    // Calculate elapsed time in seconds
    unsigned long elapsedTime = (millis() - startTime) / 1000;

    printToSerialMonitor(elapsedTime, potValue, rateOfChange);

    // Save data to a text file on the SD card
    saveDataToFile(elapsedTime, potValue, rateOfChange);
  }

  // Print potentiometer value to serial monitor for debugging 
  Serial.print("Potentiometer Value: ");
  Serial.println(potValue);

  // Store data in array
  data[dataIndex++] = potValue;

  // Check if array is full
  if (dataIndex >= 100) {
    dataIndex = 0;  // Reset index
  }

  delay(100);  // Delay between readings
}

void initializeSDCard() {
  if (SD.begin(10)) {  // Change 10 to the chip select pin you're using for the SD card
    Serial.println("SD card initialized.");
  } else {
    Serial.println("Error initializing SD card.");
    return;
  }
}

void printToSerialMonitor(unsigned long elapsedTime, int potValue, int rateOfChange) {
  // Print and save data only when recording is active
  Serial.print("(");
  Serial.print(elapsedTime);
  Serial.print("s, ");
  Serial.print(potValue);
  Serial.print(", ");


  if (rateOfChange > 0) {
    Serial.print(rateOfChange);
    Serial.print(", ");
  } else {
    Serial.print("0, ");
  }


  if (rateOfChange < 0) {
    Serial.print(-rateOfChange);
  } else {
    Serial.print("0");
  }


  Serial.println(")");
}


void saveDataToFile(unsigned long elapsedTime, int potValue, int rateOfChange) {
  // Open the data.txt file on the SD card in append mode
  File dataFile = SD.open("data.txt", FILE_WRITE);


  // If the file opened successfully, write data
  if (dataFile) {
    dataFile.print("(");
    dataFile.print(elapsedTime);
    dataFile.print("s, ");
    dataFile.print(potValue);
    dataFile.print(", ");


    if (rateOfChange > 0) {
      dataFile.print(rateOfChange);
      dataFile.print(", ");
    } else {
      dataFile.print("0, ");
    }


    if (rateOfChange < 0) {
      dataFile.print(-rateOfChange);
    } else {
      dataFile.print("0");
    }


    dataFile.println(")");
    // Close the file
    dataFile.close();
  } else {
    Serial.println("Error opening data.txt");
  }
  delay(500);
}