// ********************
// voltmeter for teaching purposes at the HTL Anichstraße,
// Department of Biomedicine and Health Technology.

// To simulate different input voltage a potentiomenter is used
//Note: This code is only for understanding and learning the programming.
// Due to the complex calculation of mean values, it is not designed to be resource-efficient.
// ********************

//Import Lib for the I2C Display
#include <LiquidCrystal_I2C.h>

//I2C Adress and column and line defintion for the used LCD
#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4



// create LCD-object based on the importet Lib
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

// definte input port for voltage measurement (potentiometer)
int analogPin = 26;

// Help variables for programming to store and print the 
// analog values resp. voltage values
int analogValue = 0;
float voltageValue = 0.0;
String outputString = "";

const int numReadings = 5;
float sensorReadings[numReadings];  // Array zur Aufbewahrung der letzten Sensorwerte
int indexArray = 0;  // Index für das Array

//setup (runs once) to initialize the ports
void setup() {
  Serial.begin(115200);
  // init (start) LCD
  lcd.init();
  // Turn on the backlight on LCD.
  lcd.backlight();
  // print the Message on the LCD on the first line. 
  lcd.print ("Voltmeter v1.0");
  Serial.println("Voltmeter v1.0");
}

void loop() {
  delay(10); // this speeds up the simulation for Wokwi only
  //read the analog value and calculate the voltage
  // ESP32: ADW 3.3V input range, 10-Bit resolution
  analogValue = analogRead(analogPin);
  voltageValue = float(analogValue * 3.3 ) / 4096.0;
  // Aktualisiere das Array mit den letzten Sensorwerten
  sensorReadings[indexArray] = voltageValue;
  indexArray = (indexArray + 1) % numReadings;

  float averageVoltage = calculateMean(sensorReadings, numReadings);  // Berechne den Durchschnitt

  //print to display on the second line
  lcd.setCursor (0, 1);
  //create the outputstring: Voltage value and Unit 
  //and print to LCD and serial output
  outputString = String(averageVoltage) + "V";
  lcd.print (outputString);
  Serial.println(outputString);
  Serial.println(sensorReadings[0]);
  //wait 500ms until reading an new value
  delay(500);
}


float calculateMean(float array[], int length) {
  if (length <= 0) {
    return 0;
  }
 float sumArray = 0;
  // Sum all elements
  for (int i = 0; i < length; ++i) {
    sumArray += array[i];
  }
  // calculate mean an return
  return sumArray / length;
}