//////////////////////////////////////////////////////
// Mokhtar Zerdali 2022. ATtiny85 oled ssd1306 I2c interface
// Attiny85 PINS


#include<avr/io.h>
#include <TinyWireM.h> // I2C library
#define TINY4KOLED_QUICK_BEGIN
#include <Tiny4kOLED.h> // this library uses the same interrupt such ISR timer0_vect

//such library is compatible for I2C interface

// Oled to ATtiny85 Pins

#define SCL PB3// Oled pin D0 I/O ATtiny 85 =PB4
#define SDA PB4// Oled pin D1 I/O ATtiny 85 =PB1
int address = 0x3C;
#define DS1621_ADDR   0x48   

/////////////////////////////////////////////
#define F_CPU 8000000UL
volatile unsigned long Countclk;
volatile unsigned long Overflowprb;
volatile unsigned long Time;


//////Oled SSD1306 code////////
void Oleddisplay_setup()
{

  //pinMode(SDA, INPUT); //data  Pin input
  oled.begin(128, 32, sizeof(tiny4koled_init_128x32br), tiny4koled_init_128x32br);
  /// Two fonts are supplied with this library, FONT8X16 and FONT6X8
  oled.setFont(FONT8X16); // (FONT8X16) (FONT6X8)
  /// To clear all the memory
  oled.clear();
  oled.on();

  //oled.fill(0xFF);
   
  oled.setCursor(1, 0);
  oled.print (("ATtiny SSD1306"));
 // oled.setCursor(1, 10);
  //oled.print(F("---------------------"));

}
/////////////////////////////////////////
void setup()  // Registers configuration
{

  DDRB =  (1 << PB5) |  (1 << PB4);
  TCCR0A = 0X00; //TCCR0A to low for normal port operation and mode 0.
  TCCR0B = 0X00; //WGM02=0
  TCNT0 = 0; //initializing the counter to 0
  //TIMSK = bit (TOIE0); //|= (1 << TOIE0); //enabling overflow >255 interrupts of  timer0
  TIMSK = bit (OCIE0B); //|= (1 << TOIE0); //enabling overflow >255 interrupts from compB
  OCR0B = 0xFF; //valeur  max 255 to compare with TCNT0
  sei(); //enabling global interrupt

}

void Pulse_RB()  // pulse rate beat program
{
  Overflowprb = 0;
  TCCR0B |= (1 << CS00); //No prescaling clk
  // Mode sense of MCUCR Register to choose the adequate sense
  MCUCR = (1 << ISC01); //3/ FALLING mode sense
  //MCUCR = bit(ISC01) | bit(ISC00); //4// RISING mode sense
}

ISR (TIMER0_COMPB_vect) //Interrupt vector for Timer0 by
//comparing the register bit TCNT0 to OCR0B=0xFF
{
  {
    Overflowprb++; // count number of overflow
  }
}
// End of TIMER0_OVF_vect

void display_test()
{
oled.fill(0xFF);
  // Swap which half of RAM is being written to, and which half is being displayed
  // This is equivalent to calling both switchRenderFrame and switchDisplayFrame
  //oled.switchFrame();
  //delay(1000);
}

int main()
{
  
  Oleddisplay_setup();
  setup();
  Pulse_RB();

  while (1)
  {

    Countclk = TCNT0 + (Overflowprb << 8); //n° overflow*256
    Time = 0.000125 * Countclk; // 8MHz ; clk : 125 ns.

    oled.begin();
    oled.setCursor(1, 10) ;  // Column / Line couple
    oled.print("Clk:");
    oled.print(Time, 1);
    oled.print("ms");
PORTB = 0b00010000;
    //oled.print(millis());
  }

}