#include <LiquidCrystal.h>
#include <Wire.h>

// lcd(RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(3, 4, 5, 6, 7, 8);
// Input pin 2 (INT0)

byte car_q[8] = {B00000,B00000,B01101,B10011,B10011,B01111,B00001,B00001};
byte e_aigu[7] = {B00010,B00100,B01110,B10001,B11111,B10000,B01110};
byte virgule[8] = {B00000,B00000,B00000,B00000,B00000,B01100,B00100,B01000};
byte pts[7] = {B00000,B00000,B01100,B01100,B00000,B01100,B01100};

void setup() 
{
  lcd.createChar(1, car_q);
  lcd.createChar(2, e_aigu);
  lcd.createChar(3, virgule);
  lcd.createChar(4, pts);
  
  lcd.begin(16, 2);
  lcd.setCursor(1, 0);
  lcd.print("Fr\2\1. secteur\4");
}

volatile unsigned long startTime;
volatile unsigned long endTime;
volatile unsigned long count;

void trigger()
{
  attachInterrupt(0, start, RISING);
}

void start()
{
  startTime = micros();
  attachInterrupt(0, pulse, RISING);
}

void pulse()
{
  endTime = micros();
  count++;
}
float getFrequency(unsigned int sampleTime)
{
  count = 0;
  attachInterrupt(0, trigger, RISING);  
  delay(sampleTime);
  detachInterrupt(0);
  
  if (count == 0)
  {
    return 0;
  }
  else
  {
    return float(1000000 * count) / float(endTime - startTime);
  }
}
float lastFreq = 0;
//-----------------------------------------------
void loop()
{
  float freq = 0;
  float period = 0;  

  if (lastFreq > 5000 || lastFreq == 0)
  {
    freq = 1000 * getFrequency(1000);
  }
  lastFreq = freq;
  
  unsigned int Hz = (freq / 1000);
  unsigned int mHz = freq - (Hz * 1000);

  lcd.setCursor(0, 1);
  {
    lcd.print("  ");
    print3digit(Hz, ' ');
    lcd.print("\3");
    print3digit(mHz, '0');
  }
  lcd.print(" Hz");
}
//-----------------------------------------------

void print3digit(int n, char leadingchar)
{
  if (n <100)
  {
    lcd.print(leadingchar);
  }  
  if (n <10)
  {
    lcd.print(leadingchar);  
  }
  lcd.print(n);
}