#include <Wire.h>

#define trig 23
#define echo 18
float distancia;
float duracion;
float metros;

byte conf[] = {3, 3, 3, 2, 2, 8, 0, 14, 0, 1, 0, 6};
byte tiempos[] = {15, 5, 1, 1, 1, 1, 1, 1}; //15, 5, 1, 1, 1, 1, 1, 1
bool rw = 0;
bool rs;
bool LED = 1;
byte pcf_addr = 0x27;

char mens1[] = "CESAR ROJAS 7-8 ";
char mens2[] = "Distancia:";

void sendnibble(byte n, byte l, byte w, byte s) {
  byte dato = (n << 4) | (l << 3) | 0x04 | (w << 2) | s;
  Wire.beginTransmission(pcf_addr);
  Wire.write(dato);
  Wire.endTransmission();
  dato = dato & 0xfb;
  Wire.beginTransmission(pcf_addr);
  Wire.write(dato);
  Wire.endTransmission();
}

void sendbyte(char n) {
  byte dat = n >> 4;
  sendnibble(dat, LED, rw, rs);
  sendnibble(n, LED, rw, rs);
}

void setup() {
  Serial.begin(115200);
  pinMode(trig,OUTPUT);
  pinMode(echo,INPUT);

Wire.begin();
  rs = 0;
  for (char i = 0; i <= 11; i++) {
    delay(tiempos[i]);
    sendnibble(conf[i], LED, rw, rs);
  }
  rs = 1;
  for (char i = 0; i < 16; i++) {
    sendbyte(mens1[i]);
  }
  updateDisplay();
  rs = 0;
  sendbyte(0xC0);
  rs = 1;
  for (char i = 0; i < 10; i++) {
    sendbyte(mens2[i]);
  } 
}

  void loop(){   
  digitalWrite(trig,HIGH);
  delayMicroseconds(1000);
  digitalWrite(trig,LOW);
  duracion=pulseIn(echo, HIGH);
  distancia=(duracion*0.034)/2;
  delayMicroseconds(500);
  metros=distancia/100;

  rs = 0;
  sendbyte(0xca); //0x88
  rs = 1;
  updateDisplay();
  }

void updateDisplay() {
  char mets[10]; 
  sprintf(mets,"%.3fM", metros);
  for (char i = 0; i < 9; i++) {
    sendbyte(mets[i]);
  }
}