#include <string.h>
#define D0 0
#define D1 1
#define D2 2
#define D3 3
#define D4 4
#define D5 5
#define D6 6
#define D7 7
#define E 8
#define RS 9

#define LEFT 0
#define RIGHT 1

uint8_t cursorPosition = 0;

void setup()
{
  //set all pins to output
  for (int i = 0; i <= 10; i++)
  {
    pinMode(i, OUTPUT);
    digitalWrite(i, LOW);
  }
  
  initDisplay();
  setCursor(0, 0);
  writeString("Witam wszystkich zebranych");
  
  
  // Experimenting with the arduino registers
  // Set the data direction of the onboard LED
  *((uint8_t*)0x24) = 0b00100000;
}

void initDisplay()
{
  clearDataBus();
    
  //set 8 bit mode, 2-line display, 5*8  font
  digitalWrite(D7, LOW);
  digitalWrite(D6, LOW);
  digitalWrite(D5, HIGH);
  digitalWrite(D4, HIGH); // 8-bit mode
  digitalWrite(D3, HIGH); // 2 line
  digitalWrite(D2, LOW); // 5*8 character font
  
  enable();
  // display ON/OFF control
  digitalWrite(D7, LOW);
  digitalWrite(D6, LOW);
  digitalWrite(D5, LOW);
  digitalWrite(D4, LOW);
  digitalWrite(D3, HIGH);
  digitalWrite(D2, HIGH); // 1 - display on
  digitalWrite(D1, LOW); // 1 - cursor on
  digitalWrite(D0, LOW); // 0 - blink off, 1 - blink on
  
  enable();
  
  // Entry mode set
  digitalWrite(D7, LOW);
  digitalWrite(D6, LOW);
  digitalWrite(D5, LOW);
  digitalWrite(D4, LOW);
  digitalWrite(D3, LOW);
  digitalWrite(D2, HIGH);
  digitalWrite(D1, LOW); // 0 = decrement, 1 = increment
  digitalWrite(D0, LOW); // 1 = accompanies display shift
  
  enable();
  
  clearDisplay();
  
  digitalWrite(RS, HIGH);
  clearDataBus();
}

void writeChar(char c)
{
  // array to hold binary representation of the ASCII code
  int bit[8];
  
  // Convert ASCII code to binary
  for (int i = 0; i < 8; i++)
  {
    bit[i] = c % 2;
    c = c / 2;
  }
  
  // Write bits to display
  digitalWrite(D7, bit[7]);
  digitalWrite(D6, bit[6]);
  digitalWrite(D5, bit[5]);
  digitalWrite(D4, bit[4]);
  digitalWrite(D3, bit[3]);
  digitalWrite(D2, bit[2]);
  digitalWrite(D1, bit[1]);
  digitalWrite(D0, bit[0]);  
  
  // Toggle enable bit
  enable();
  cursorPosition++;
  clearDataBus();
}

void writeString(const char* str)
{ // If the text is longer than one row, than it's divided to the second one
  if (strlen(str) > 16) { 
    for (int i = 0; i < 16; i++)
    {
     writeChar(str[i]);
    }
    setCursor(1, 0);
    for (int i = 16; i < strlen(str); i++)
    {
     writeChar(str[i]);
    }

  } else {
    for (int i = 0; i < strlen(str); i++)
    {
     writeChar(str[i]);
    }
  
  }
}

void enable()
{
  // Cycle enable bit to send
  digitalWrite(E, HIGH);
  digitalWrite(E, LOW);
}

void clearDisplay()
{
  clearDataBus();
  
  digitalWrite(RS, LOW);
  
  digitalWrite(D0, HIGH);
  enable();
  
  clearDataBus();
  digitalWrite(RS, HIGH);
  
  cursorPosition = 0;
}

void shiftCursor(uint8_t shiftRight)
{
  clearDataBus();
  
  digitalWrite(RS, LOW);
  
  digitalWrite(D7, LOW);
  digitalWrite(D6, LOW);
  digitalWrite(D5, LOW);
  digitalWrite(D4, HIGH);
  digitalWrite(D3, LOW); // 0 = cursor move, 1 = display shift
  digitalWrite(D2, shiftRight); // 0 = shift left, 1 = shift right
  digitalWrite(D1, LOW);
  digitalWrite(D0, LOW);
  
  enable();
  
  if (shiftRight)
  {
    cursorPosition++;
  }
  else
  {
    cursorPosition--;
  }
  
  clearDataBus();
  digitalWrite(RS, HIGH);
}

void setRow(uint8_t row)
{
  clearDataBus();
  if (row == 1)
  {    
    for (int i = cursorPosition; i < 40; i++)
    {
      shiftCursor(true);
    }
  }
  else if (row == 0)
  {
    for (int i = cursorPosition; i >= 0; i--)
    {
      shiftCursor(false);
    }
  }
  else
  {
    return;
  }
}

void setCursor(uint8_t row, uint8_t col)
{
  uint8_t position = col;
  if (row >= 1)
  {
    position += 40;
  }
  
  while (cursorPosition != position)
  {
    if (cursorPosition < position)
    {
      shiftCursor(RIGHT);
    }
    else
    {
      shiftCursor(LEFT);
    }
  }
}

void clearDataBus()
{
  for (int i = 0; i < 8; i++)
  {
    digitalWrite(i, LOW);
  }
}

void loop()
{
  /* This is just a blink program except it
   modifyes the registers rather than using
   digitalWrite() */
  // Enable LED 
  *((uint8_t*)0x25) = 0b00100000;
  delay(500);
  // Disable LED
  *((uint8_t*)0x25) = 0b00000000;
  delay(500);
}
// made by: pio200