// REQUIRES the following Arduino libraries:
// - Adafruit GFX graphics core lib: https://github.com/adafruit/Adafruit-GFX-Library
// - Adafruit OLED mono displays lib: libray https://github.com/adafruit/Adafruit_SSD1306
// - SoftwareSerial : bluetooth

/* tutos et références
   https://www.e-techno-tutos.com/2021/03/10/bluetooth-hc-05/
   https://www.youtube.com/watch?v=eDKbRlADvA0
   https://www.carnetdumaker.net/articles/faire-un-tachymetre-avec-une-carte-arduino-genuino-pour-lire-la-vitesse-de-rotation-dun-ventilateur-de-pc/
*/

#include "time.h"

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SoftwareSerial.h>
#include <Wire.h>

#define BUTTONPIN      2                        // Digital IO pin connected to the button.

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library.
// On an arduino UNO or Nano:       A4(SDA), A5(SCL)
#define SCREEN_WIDTH 128                        // OLED display width, in pixels
#define SCREEN_HEIGHT 64                        // OLED display height, in pixels
#define OLED_RESET    -1                        // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C                     //< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Mapping Arduino Digital ports to Bluetooth Serial
#define BT_TX 10
#define BT_RX 11

#define DEBOUNCE 3                              // debounce latency in ms
// const int IR_distance = A0;                  // analog input
#define IR_detection_pin 3                      // digital input   12
unsigned long elapsed_time, elapsed_time4min, elapsed_time4sec, start_time4min, start_time4sec;
volatile int NbRPMin = 0;
volatile int NbRPSec = 0;
int NbRPM = 0;
int prevNbRPMin = 0;
int nCoeff = 1;

volatile unsigned long IR_time;
volatile unsigned long IR_last_time = 0;

volatile unsigned long periode = 0;             // comptage retour info ventilo

word Median_filter(word t);                     // filtre lissage sur 5 mesures comptage-tours

// SoftwareSerial BT_Serial(BT_TX, BT_RX);      // declaring second serial port.

void setup() {
   // Serial.begin(115200);

   // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
   if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x32
      Serial.println(F("SSD1306 allocation failed"));
      for(;;); // Don't proceed, loop forever
   }

   // Show initial display buffer contents on the screen --
   // the library initializes this with an Adafruit splash screen.
   display.display();
   delay(1000);

   // initialize the pushbutton pin as input:
   //pinMode(BUTTONPIN, INPUT);
   //pinMode(BUTTONPIN, INPUT_PULLUP);
   // Uno and Nano : interruptions only on D2 and D3
   // attachInterrupt(digitalPinToInterrupt(BUTTONPIN), onButtonD2Event, RISING);

   // initialize IR pins
   // pinMode(IR_detection_pin, INPUT);
   pinMode(IR_detection_pin, INPUT_PULLUP);
   attachInterrupt(digitalPinToInterrupt(IR_detection_pin), onInfraRedD3Event, RISING);

   start_time4min = start_time4sec = millis();
}

//void onButtonD2Event() {
//   nCoeff = nCoeff < 6 ? ++nCoeff : 1;
//}

void onInfraRedD3Event() {
   //IR_not_detected = digitalRead( IR_detection_pin);
   // 1 no detection
   // 0 detection
   // Serial.println(IR_not_detected);
   IR_time = millis();
   if (IR_time - IR_last_time > DEBOUNCE)       // temporisation x millisecondes pour éviter de compter trop vite :-)
   {
      ++NbRPMin;
      ++NbRPSec;
      IR_last_time = IR_time;
   }
}

void loop(){

   display.cp437(true);                         // Use full 256 char 'Code Page 437' font
   display.clearDisplay();                      // Clear the buffer

   display.setTextColor(SSD1306_WHITE);         // Draw white text
   display.setTextSize(1);                      // Normal 1:1 pixel scale
   display.setCursor(0,0);                      // Start at left-top corner
   display.println(F("Revolutions / minute"));

   // affichage compptage nombre de tours comptés pendant cette minute
   display.setCursor(0, 56);
   //display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
   display.print(nCoeff * NbRPMin);

   // affichage compptage nombre de tours comptés minute précédente
   //display.setCursor(64, 56);
   //display.print(F("Coeff * "));
   //display.print(nCoeff);
   display.setCursor(50, 56);
   display.print(nCoeff * prevNbRPMin);

   // affichage comptage secondes
   display.setCursor(116, 56);
   display.print(int((elapsed_time4min - start_time4min) / 1000));

   // affichage vitesse moyenne calculée en tours/minute
   display.setTextSize(3);
   display.setCursor(32, 20);
   display.print(nCoeff * NbRPM);

   display.display();

   elapsed_time4min = elapsed_time4sec = millis();
   elapsed_time = elapsed_time4sec - start_time4sec;
   // comptage nombre de tours sur une seconde extrapolés à la minute
   if (elapsed_time > 1000) {
      NbRPM = Median_filter(NbRPSec * 1000.0 * 60 / elapsed_time);
      start_time4sec = elapsed_time4sec;
      NbRPSec = 0;
   }
   // remise à zéro du comptage sur la minute
   if ((elapsed_time4min - start_time4min) > 60000) {
      start_time4min = elapsed_time4min;
      //Serial.println(NbRPMin);
      prevNbRPMin = NbRPMin;
      NbRPMin = 0;
   }
}