#include <LiquidCrystal_PCF8574.h>

LiquidCrystal_PCF8574 lcd(0x27);

#define pin_I0 4

#define pin_I1 5

#define pin_I2 6

#define pin_I3 7

#define I0 digitalRead(pin_I0)

#define I1 digitalRead(pin_I1)

#define I2 digitalRead(pin_I2)

#define I3 digitalRead(pin_I3)

#define Q0 19

#define Q1 18

#define Q2 10

#define Q3 3

char texto[] = "digital I/O";

byte pin_state_high[] = {

  0b00000,

  0b11111,

  0b11111,

  0b11111,

  0b11111,

  0b11111,

  0b11111,

  0b00000

};

byte pin_state_low[] = {

  0b00000,

  0b11111,

  0b10001,

  0b10001,

  0b10001,

  0b10001,

  0b11111,

  0b00000

};

void display_update() {

  lcd.setCursor(0, 0);

  lcd.print(texto);

  lcd.setCursor(0, 1);

  lcd.print("I: ");

  lcd.write(I0);

  lcd.write(I1);

  lcd.write(I2);

  lcd.write(I3);

  lcd.setCursor(0, 2);

  lcd.print("   0123");

  lcd.setCursor(0, 3);

  lcd.print("Q: ");

  lcd.write(digitalRead(Q0));

  lcd.write(digitalRead(Q1));

  lcd.write(digitalRead(Q2));

  lcd.write(digitalRead(Q3));

}

void setup() {

  // put your setup code here, to run once:

  pinMode(pin_I0, INPUT);

  pinMode(pin_I1, INPUT);

  pinMode(pin_I2, INPUT);

  pinMode(pin_I3, INPUT);

  pinMode(Q0, OUTPUT);

  pinMode(Q1, OUTPUT);

  pinMode(Q2, OUTPUT);

  pinMode(Q3, OUTPUT);

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

  lcd.createChar(0, pin_state_low);

  lcd.createChar(1, pin_state_high);

  delay(200);

  lcd.setBacklight(255);

}

void loop() {

  // put your main code here, to run repeatedly:

  digitalWrite(Q0, I0);

  digitalWrite(Q1, I1);

  digitalWrite(Q2, I2);

  digitalWrite(Q3, I3);

  display_update();

}