// Código original do Rodrigo
//  http://labdegaragem.com/forum/topics/frequencimetro-e-voltimetro

#include <LiquidCrystal_I2C.h>
#include <Wire.h>
LiquidCrystal_I2C lcd(0x20,20,4);
//Frequencia
long tempo, freq;
int pulsos;
boolean pulso;
//Tensão
#define resistance_R500 1000000
#define resistance_V2 10000
#define caliberation_V2 1.05
#define range500_mul (resistance_R500 / resistance_V2) * caliberation_V2
#define resistance_R2 1000
int adc_value = 0;
int voltage_peak_value = 0;
float voltage_average_value = 0;
float dc_voltage_V0 = 0;
int ac_voltage_V0 = 0;
unsigned long sample_count = 0;
void setup()
{
  pulso=HIGH;
  pinMode(2,INPUT);
  Serial.begin(9600);
}
void loop()
{
  tempo = millis();
    Serial.println(tempo);
  if(digitalRead(2)==HIGH)
  {
      if(pulso==HIGH)
      {
          pulsos = pulsos + 1;
      }
      pulso=LOW;
  }
  else
  {
      pulso=HIGH;
  }
  if(tempo%1000==0)
    freq = (pulsos/2.0);

  else;
    delayMicroseconds(10);

  voltage_peak_value = 0;
  for(sample_count = 0; sample_count < 5000; sample_count ++)
  {
      adc_value = analogRead(A1);
      if(voltage_peak_value < adc_value)
          voltage_peak_value = adc_value;
      else;
          delayMicroseconds(10);
  }
  dc_voltage_V0 = voltage_peak_value * 0.00488;
  ac_voltage_V0 = (dc_voltage_V0 / 1.414) * range500_mul;

  Serial.print("FREQUENCIMETRO: ");
  Serial.print(freq);
  Serial.print("Hz ");
  Serial.print("VOLTIMETRO: ");
  Serial.println(ac_voltage_V0);
  pulsos=0;

}