Sensing Current with an INA219 and Storing Data on SD Card

//ref: https://www.youtube.com/watch?v=lrugreN2K4w
#include <Wire.h>
#include <Adafruit_INA219.h>
#include <Adafruit_SSD1306.h>
// inclure aussi la librarie Adafruit_BusIO-master meme si il n'y a pas d'include ici.
#include <SPI.h>
#include "SdFat.h"
SdFat SD;

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
Adafruit_INA219 ina219;

unsigned long previousMillis = 0;
unsigned long dataAquisitionInterval_ms = 250;
const int chipSelect = 10;
float shuntvoltage = 0;
float busvoltage = 0;
float current_mA = 0;
float power_mw = 0;
float current_mAh = 0;
float power_mWh = 0;
float loadvoltage = 0;
File DataLogFile;
File CurFile;

int boot = 1;

int days;     //number of days
int hours;   //the remainder from days division (in milliseconds) divided by hours, this gives the full hours
int minutes; //and so on...
int seconds;


// Moving Average VAR1
const int VAR1_numVAR1_readings = 5;
float VAR1_readings[VAR1_numVAR1_readings];      // the readings from the analog input
int VAR1_readIndex = 0;              // the index of the current reading
float VAR1_total = 0;                  // the running total

// DEBOUNCE B1
const int B1_buttonPin = 3;    // the number of the pushbutton pin
int B1_State = LOW;         // the current state of the output pin
int B1_ActualState;             // the current reading from the input pin
int B1_LastState = LOW;   // the previous reading from the input pin
unsigned long B1_lastDebounceTime = 0;  // the last time the output pin was toggled
unsigned long B1_debounceDelay = 50;    // the debounce time; increase if the output flickers
const int ledPin = 4;      // the number of the LED pin


void setup()
{
  SD.begin(chipSelect);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  ina219.begin();

  // DEBOUNCE B1
  pinMode(B1_buttonPin, INPUT);
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

}

void loop()
{

  if (boot == 1)
  {
    CurFile = SD.open("header.txt", FILE_WRITE);
    if (CurFile)
    {
      CurFile.println("day,hrs,voltage,current_mA,power_mWh,current_mAh");
      CurFile.close();
      boot = 0;
    }
    //    B1_State = LOW;
    digitalWrite(ledPin, LOW);
  }

  // DEBOUNCE B1
  B1_StartStop_SD();
  // set the LED:
  digitalWrite(ledPin, B1_State);

  unsigned long currentMillis = millis();

  //Calculation for the Up Time
  long day = 86400000; // 86400000 milliseconds in a day
  long hour = 3600000; // 3600000 milliseconds in an hour
  long minute = 60000; // 60000 milliseconds in a minute
  long second =  1000; // 1000 milliseconds in a second

  days = currentMillis / day ;                                //number of days
  hours = (currentMillis % day) / hour;                       //the remainder from days division (in milliseconds) divided by hours, this gives the full hours
  minutes = ((currentMillis % day) % hour) / minute ;         //and so on...
  seconds = (((currentMillis % day) % hour) % minute) / second;
  //Calculation for the Up Time

  if (currentMillis - previousMillis >= dataAquisitionInterval_ms)
  {
    previousMillis = currentMillis;
    ina219values();

    //>>> writing to the card
    if (B1_State == HIGH)
    {
      DataLogFile = SD.open("DataLog.txt", FILE_WRITE);
      if (DataLogFile)
      {
        DataLogFile.print(days);
        DataLogFile.print(",");

        if (hours < 10) DataLogFile.print('0');
        DataLogFile.print(hours);
        DataLogFile.print(":");
        if (minutes < 10) DataLogFile.print('0');
        DataLogFile.print(minutes);
        DataLogFile.print(":");
        if (seconds < 10) DataLogFile.print('0');
        DataLogFile.print(seconds);
        DataLogFile.print(",");

        DataLogFile.print(loadvoltage);
        DataLogFile.print(",");
        DataLogFile.print(current_mA);
        DataLogFile.print(",");
        DataLogFile.print(power_mWh);
        DataLogFile.print(",");
        DataLogFile.println(current_mAh);
        DataLogFile.close();
      }  //>>> writing to the card
    }

    displaydata();
  }

}

void displaydata()
{
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(1);

  //first line
  display.setCursor(0, 0);

  display.print(days);
  display.print("d ");

  if (hours < 10) display.print('0');
  display.print(hours);
  display.print(":");
  if (minutes < 10) display.print('0');
  display.print(minutes);
  display.print(":");
  if (seconds < 10) display.print('0');
  display.print(seconds);
  display.print(" -> ");

  display.print(loadvoltage);
  display.print("v ");


  //second ling
  display.setCursor(0, 10);
  display.print(power_mw);
  display.print("mW ");
  display.print(abs(current_mA));
  display.print("mA");

  //third ling
  display.setCursor(0, 20);
  display.print(power_mWh);
  display.print("mWh ");
  display.print(current_mAh);
  display.print("mAh");
  display.display();
}

void ina219values()
{
  shuntvoltage = (ina219.getShuntVoltage_mV());
  busvoltage = (ina219.getBusVoltage_V());
  current_mA = MovingAVG_VAR1(ina219.getCurrent_mA());
  loadvoltage = (busvoltage + (shuntvoltage / 1000));

  // to avoid inconsistant readings, set to zero when values are below zero
  power_mw = (loadvoltage * current_mA);
  if (power_mw < 0)
  {
    current_mA = 0;
    loadvoltage = 0;
    power_mw = 0;
  }

  power_mWh = power_mWh + (power_mw       / (60 * 60) / (1000 / dataAquisitionInterval_ms));
  current_mAh = current_mAh + (current_mA / (60 * 60) / (1000 / dataAquisitionInterval_ms));

}




float MovingAVG_VAR1(float ValueToAVG)
{
  float VAR1_average = 0;                // the average
  // subtract the last reading:
  VAR1_total = VAR1_total - VAR1_readings[VAR1_readIndex];
  // read from the sensor:
  VAR1_readings[VAR1_readIndex] = ValueToAVG;
  // add the reading to the VAR1_total:
  VAR1_total = VAR1_total + VAR1_readings[VAR1_readIndex];
  // advance to the next position in the array:
  VAR1_readIndex = VAR1_readIndex + 1;
  // if we're at the end of the array...
  if (VAR1_readIndex >= VAR1_numVAR1_readings)
    VAR1_readIndex = 0;
  // calculate the VAR1_average:
  VAR1_average = VAR1_total / VAR1_numVAR1_readings;
  // send it to the computer as ASCII digits
  return VAR1_average;
}


void B1_StartStop_SD()
{ // DEBOUNCE B1
  int reading = digitalRead(B1_buttonPin);
  if (reading != B1_LastState)
    B1_lastDebounceTime = millis();
  if ((millis() - B1_lastDebounceTime) > B1_debounceDelay)
  {
    if (reading != B1_ActualState)
    {
      B1_ActualState = reading;
      if (B1_ActualState == HIGH)
        B1_State = !B1_State;
    }
  }
  B1_LastState = reading;
}