// ATtiny85 - MAX7219 Dot Matrix
// https://akuzechie.blogspot.com/2022/01/attiny85-max7219-dot-matrix.html
// https://www.youtube.com/watch?v=0jKfozjTYIs

// ATtiny85 - DS1307 Real-Time Clock
// https://akuzechie.blogspot.com/2022/02/attiny85-ds1307-real-time-clock.html
// https://www.youtube.com/watch?v=o9HGWWoQkCo


//---------------------------------------
//ATtiny85 - DS1307 RTC Read Time & Date
//---------------------------------------
#include <TinyWireM.h>
//----------------------
extern "C" {void delay_ms(); void delay_us();}
//---------------------------------------------
byte read_DS1307[6];
byte numeral[] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
unsigned long millisCapture = millis(), myDelay = 30000;
boolean colon_ONOFF = false;
//===================================================================
void setup()
{
  pinMode(1, OUTPUT);
  TinyWireM.begin();
  TM1637_init();
}
//===================================================================
void loop()
{
  //write to set pointer register to seconds
  //-----------------------------------------
  TinyWireM.beginTransmission(0x68);
  TinyWireM.send(0x00);                 //point to Seconds register
  TinyWireM.endTransmission();
  //----------
  //read time
  //----------
  TinyWireM.requestFrom(0x68, 3);
  if(TinyWireM.available())
  {
    read_DS1307[0] = TinyWireM.receive(); //read seconds
    read_DS1307[1] = TinyWireM.receive(); //read minutes
    read_DS1307[2] = TinyWireM.receive(); //read hours
  }
  delay_ms();
  //--------------------------------------
  //write to set pointer register to date
  //--------------------------------------
  TinyWireM.beginTransmission(0x68);
  TinyWireM.send(0x04);                 //point to Date register
  TinyWireM.endTransmission();
  //----------
  //read date
  //----------
  TinyWireM.requestFrom(0x68, 3);
  if(TinyWireM.available())
  {
    read_DS1307[3] = TinyWireM.receive(); //read day
    read_DS1307[4] = TinyWireM.receive(); //read month
    read_DS1307[5] = TinyWireM.receive(); //read year
  }
  delay_ms();
  //----------------------------------------------------------------
  if(millis() - millisCapture > myDelay) disp_date();
  //----------------------------------------------------------------
  if((read_DS1307[2] & 0x10) >> 4 == 0)
  {
    send_byte(0xC0); send_byte(0x00); //turn OFF digit 0
  }
  else disp_digit(0xC0, ((read_DS1307[2] & 0x10) >> 4));
  //----------------------------------------------------------------
  if(colon_ONOFF == true) disp_colon(0xC1, (read_DS1307[2] & 0x0F));
  else disp_digit(0xC1, (read_DS1307[2] & 0x0F));
  //----------------------------------------------------------------
  disp_digit(0xC2, ((read_DS1307[1] & 0xF0) >> 4));
  disp_digit(0xC3, (read_DS1307[1] & 0x0F)); 
  //----------------------------------------------------------------
  byte AM_PM = read_DS1307[2] & 0x20;
  if(AM_PM == 0x20) digitalWrite(1, HIGH);
  else digitalWrite(1, LOW);
  //----------------------------------------------------------------
  delay(1000);
}
//===================================================================
void disp_date()
{
  clr_disp(); delay(500);
  //---------------------------------------------------
  disp_digit(0xC1, (read_DS1307[3] & 0x0F));
  disp_digit(0xC0, ((read_DS1307[3] & 0xF0) >> 4));
  //---------------------------------------------------
  disp_digit(0xC3, (read_DS1307[4] & 0x0F));
  disp_digit(0xC2, ((read_DS1307[4] & 0x10) >> 4));
  //---------------------------------------------------
  delay(2000);
  clr_disp(); delay(500);
  //---------------------------------------------------
  disp_digit(0xC0, 2);
  disp_digit(0xC1, 0);
  disp_digit(0xC3, (read_DS1307[5] & 0x0F));
  disp_digit(0xC2, ((read_DS1307[5] & 0xF0) >> 4));
  //---------------------------------------------------
  delay(2000);
  clr_disp(); delay(500);
  millisCapture = millis();
}
//===================================================================
void disp_digit(byte address, byte digit)
{
  send_byte(address); send_byte(numeral[digit]);
  // switch(digit)
  // {
  //   case 0: send_byte(address); send_byte(numeral[0]); break;
  //   case 1: send_byte(address); send_byte(numeral[1]); break;
  //   case 2: send_byte(address); send_byte(numeral[2]); break;
  //   case 3: send_byte(address); send_byte(numeral[3]); break;
  //   case 4: send_byte(address); send_byte(numeral[4]); break;
  //   case 5: send_byte(address); send_byte(numeral[5]); break;
  //   case 6: send_byte(address); send_byte(numeral[6]); break;
  //   case 7: send_byte(address); send_byte(numeral[7]); break;
  //   case 8: send_byte(address); send_byte(numeral[8]); break;
  //   case 9: send_byte(address); send_byte(numeral[9]);
  // }
  colon_ONOFF = !colon_ONOFF;
}
//===================================================================
void disp_colon(byte address1, byte digit1)
{
  send_byte(address1); send_byte(numeral[digit1]|0x80);
  // switch(digit1)
  // {
  //   case 0: send_byte(address1); send_byte(numeral[0]|0x80); break;
  //   case 1: send_byte(address1); send_byte(numeral[1]|0x80); break;
  //   case 2: send_byte(address1); send_byte(numeral[2]|0x80); break;
  //   case 3: send_byte(address1); send_byte(numeral[3]|0x80); break;
  //   case 4: send_byte(address1); send_byte(numeral[4]|0x80); break;
  //   case 5: send_byte(address1); send_byte(numeral[5]|0x80); break;
  //   case 6: send_byte(address1); send_byte(numeral[6]|0x80); break;
  //   case 7: send_byte(address1); send_byte(numeral[7]|0x80); break;
  //   case 8: send_byte(address1); send_byte(numeral[8]|0x80); break;
  //   case 9: send_byte(address1); send_byte(numeral[9]|0x80);
  // }
  send_byte(0xC1); send_byte(0x00);
  colon_ONOFF = !colon_ONOFF;
}
//===================================================================
void TM1637_init()
{
  send_byte(0x8F);        //command for display brightness level (max)
  send_byte(0x44);        //command for single address mode
  clr_disp();             //clear display
}
//===================================================================
void clr_disp()
{
  for(byte i=0; i<=4; i++)
  {
    send_byte(0xC0 + i);
    send_byte(0);
  }
}
//===================================================================
void send_byte(byte Rx_byte)
{
  DDRB |= (1 << PB4);     //PB4 o/p: DIO line
  DDRB |= (1 << PB3);     //PB3 o/p: CLK line
  //----------------------------------------------------------
  PORTB &= ~(1 << PB4);   //START condition
  delay_us();
  PORTB &= ~(1 << PB3);
  delay_us();
  //----------------------------------------------------------
  shiftOut(4, 3, LSBFIRST, Rx_byte); //shift out byte LSB 1st
  //----------------------------------------------------------
  DDRB &= ~(1 << PB4);    //MCU releases DIO line
  delay_us();
  PORTB |= (1 << PB3);    //9th CLK for ACK
  delay_us();
  PORTB &= ~(1 << PB3);
  delay_us();
  DDRB |= (1 << PB4);     //MCU reclaims DIO line
  delay_us();
  //----------------------------------------------------------
  PORTB |= (1 << PB3);    //END condition
  delay_us();
  PORTB |= (1 << PB4);
  delay_us();
}