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

// To simulate different input voltage a potentiometer is used
// ********************

//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 = "";

//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;

  //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(voltageValue) + "V";
  lcd.print (outputString);
  Serial.println(outputString);
  //wait 500ms until reading an new value
  delay(500);
}