// Program for attiny3216 to Hall magnetic sensor and display it on 4x20 LCD liquid crystal
// created by Jans Hendry
// Universitas Gadjah Mada, Indonesia
// Kamakura Node, Japan
// fab academy MIT - 2022

// the directives/predecessor
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// create lcd as an object
// format: address, num of columns, num of rows
LiquidCrystal_I2C lcd(0x27, 20, 4);

// sensor pin
const int tp_pin = 4;

void setup() {
  // start serial
  Serial.begin(9600);

  // setting up
  lcd.init();

  // turn on backlight <- the variable resistor has been adjusted
  lcd.backlight();

  // clear screen
  lcd.clear();

  // static display
  defDisplay();

  // delay
  delay(500);
}

void loop() {
  int sdata = analogRead(tp_pin); // read analogue data 
  int sensdata = 1023 - sdata;
  //  Serial.print("Sensor reading: ");
  //  Serial.println(sensdata);

  lcd.setCursor(12, 0);
  lcd.print(sdata); // raw value

  // calculate magnetic field in B
  float vout = (sensdata / 1024.0) * 5; // voltage out
  float B = 1000 * ((2*vout/3) - 5/3);
  lcd.setCursor(12, 1);
  lcd.print((int)B);
  
  // calculate magnetic field in mB
  float MB = B / 1000; // let say mega B
  lcd.setCursor(12, 2);
  lcd.print((float)MB);
  
  delay(1000); // take a break every 1 second
}

void defDisplay() {
  lcd.clear(); // clear display

  // static text
  lcd.setCursor(0, 0);
  lcd.print("Read-out ");
  lcd.setCursor(11, 0);
  lcd.print(":");

  lcd.setCursor(0, 1);
  lcd.print("Magnetic B");
  lcd.setCursor(11, 1);
  lcd.print(":");
  lcd.setCursor(19, 1);
  lcd.print("G");

  lcd.setCursor(0, 2);
  lcd.print("Magnetic MB");
  lcd.setCursor(11, 2);
  lcd.print(":");
  lcd.setCursor(18, 2);
  lcd.print("MG");
}