// Program for attiny3216 to measure the distance between sensor and object
// 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);

// variables
long dur;
long dist;
const int echoPin = 4; // echo pin
const int trigPin = 3; // trigger pin

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

  // begin lcd
  lcd.begin(20, 4);

  // setting up
  lcd.init();

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

  // clear screen
  lcd.clear();

  // static display
  defDisplay();

  // set pin as output
  pinMode(echoPin, INPUT);
  pinMode(trigPin, OUTPUT);

  delay(500); // take a breath
}

void loop() {

  // Request for distance sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  // get the distance
  dur = pulseIn(echoPin, HIGH);
  dist = (dur / 2) * 0.034;

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

  // time
  lcd.setCursor(12, 1);
  lcd.print("    ");
  lcd.setCursor(12, 1);
  lcd.print(dur / 2); // raw value

  // distance
  lcd.setCursor(12, 2);
  lcd.print("    ");
  lcd.setCursor(12, 2);
  lcd.print(dist);

  delay(1000);
}

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("Time");
  lcd.setCursor(11, 1);
  lcd.print(":");
  lcd.setCursor(17, 1);
  lcd.print("ms");

  lcd.setCursor(0, 2);
  lcd.print("Distance");
  lcd.setCursor(11, 2);
  lcd.print(":");
  lcd.setCursor(17, 2);
  lcd.print("cm");
}