#include <Keypad.h>
#include "LiquidCrystal.h"
LiquidCrystal lcd(A0,A1,A2,A3,A4,A5);
String buf = "";
String memory = "";
int um = 1;
const byte LINHAS = 4; //4 linhas
const byte COLUNAS = 4; //4 colunas
char keys[LINHAS][COLUNAS] = 

{
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'S','0','H','D'}
};
byte rowPins[LINHAS] = {9, 8, 7, 6}; 
byte colPins[COLUNAS] = {5, 4, 3, 2}; 

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, LINHAS, COLUNAS );

String v_passcode="";

void setup()
{
  Serial.begin(9600);
  lcd.begin(16,4);
  lcd.home();
  lcd.setCursor(0,0);
  lcd.print("A --> Resistencia");
  lcd.setCursor(0,1);
  lcd.print("B --> Corrente");
  lcd.setCursor(4,2);
  lcd.print("C --> Potencia");
  lcd.setCursor(4,4);
  lcd.print("* --> Menu");

}


void loop()
{
  char key = keypad.getKey();
  
  if (key != NO_KEY){
    if (key == 'A'){
      buf = "";
      resistencia();
    }
    else if (key == 'B'){
      buf = "";
      corrente();
    }
    else if (key == 'C'){
      buf = "";
      potencia();
    }
  }
}

void resistencia() {
  int i = 0;
  char key2 = keypad.getKey();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Resistencia = ");
  lcd.setCursor(0, 1);
  lcd.print("Tensao      = ");
  lcd.setCursor(4, 2);
  lcd.print("Corrente    = ");
  lcd.setCursor(4, 4);
  lcd.print("Potencia    = ");

  while(i == 0){
    char key2 = keypad.getKey();
    if(key2 == 'H'){
      
    }
    if(key2 == 'S'){
      break;
    }
    lcd.setCursor(0, 0);
    lcd.print("Resistencia = ");
    if (key2 != NO_KEY){
      memory = key2;
      buf += key2;
      lcd.print(buf);
      
    }
  }
  setup();
}
  

void corrente() {
  int i = 0;
  char key2 = keypad.getKey();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Corrente = ");
  lcd.setCursor(0, 1);
  lcd.print("Tensao   = ");
  lcd.setCursor(4, 2);
  lcd.print("Potencia = ");

  while(i == 0){
    char key2 = keypad.getKey();
    if(key2 == 'H'){
      
    }
    if(key2 == 'S'){
      break;
    }
    lcd.setCursor(0, 0);
    lcd.print("Corrente = ");
    if (key2 != NO_KEY){
      memory = key2;
      buf += key2;
      lcd.print(buf);
      
    }
  }
  setup();
}

void potencia() {
  int i = 0;
  char key2 = keypad.getKey();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Potencia = ");
  lcd.setCursor(0, 1);
  lcd.print("Tensao   = ");
  lcd.setCursor(4, 2);
  lcd.print("Corrente = ");

  while(i == 0){
    char key2 = keypad.getKey();
    if(key2 == 'H'){
      
    }
    if(key2 == 'S'){
      break;
    }
    lcd.setCursor(0, 0);
    lcd.print("Potencia = ");
    if (key2 != NO_KEY){
      memory = key2;
      buf += key2;
      lcd.print(buf);
      
    }
  }
  setup();
}