HD44780-AVR-library

Description:

This library is focused on providing a fast and simple way of communicating with the HD44780 controller while also providing low-level functionality to allow more control over the controller.

Note:

If this library doesn't work correctly, try redefining LCD_DELAY. This value affects time that HD44780 chip is given to process data packets (for my display it works with 1500). Amount of time that HD44780 needs is tied to clock frequency of to the chip. Theese values are specified in the datasheet on page 24.

It's either this or I fucked up something in the code.

Targets:

AVR devices

Limitations:

• Only supports 4-bit interface
• Doesn't support reading from display memory
• All pins have to be connected within a single port (PORTB, PORTD, etc..)

HD44780 LCD pinout:

Usage:

Getting started:

1. Pin configuration:

Warning: All pins have to be connected within a single port!

Create instance of PinConfig struct:

PinConfig config = {.ddr = &DDRD, .port = &PORTD, .d0 = 16, .d1 = 32, .d2 = 64, .d3 = 128, .rs = 4, .en = 8};

Values in PinConfig struct:

Assigned values must be corresponding to values of individual bits in port register:

2. Initializing the display

Call the LCD_init(PinConfig*) function with arguments:

1. pointer to an instance of the PinConfig struct

  LCD_init(&config);

Warning: If you change values in config you will also need to reinitialize the display

Display is off by default, to turn it on call LCD_on() function:

  LCD_on();

3. Printing a message:

You can prit individual characters with LCD_write_char():

  LCD_write_char('H');
  LCD_write_char('e');
  LCD_write_char('l');
  LCD_write_char('l');
  LCD_write_char('o');
  LCD_write_char(' ');
  LCD_write_char('w');
  LCD_write_char('o');
  LCD_write_char('r');
  LCD_write_char('l');
  LCD_write_char('d');
  LCD_write_char('!');

To clear the display use LCD_clear():

  LCD_clear();

To write string use LCD_write_string(char*) with arguments:

1. pointer to the string

  char greetings[] = "Hello world!";
  LCD_write_string(&greetings[0]);

4. Reference:

int LCD_init(PinConfig* config):

• Description:

  Initializes the HD44780 interface
  

• Arguments:

  1. Pointer to instance of PinConfig struct
  

• Return value: int:

  0 if success
  1 if pin verification failed (some values specified in provided config are the same or 0)
  

void LCD_instruction(uint8_t instruction):

• Description:

  Sends instruction to the display (list of instruction can be found in the datasheet on page 24)
  

• Arguments:

  1. Instruction
  

• Return value: void:

  none
  

void LCD_write_char(char character):

• Description:

  Writes one character to the display
  

• Arguments:

  1. ASCII character
  

• Return value: void:

  none
  

void LCD_clear():

• Description:

  Clears the display
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_set_cursor(uint8_t row, uint8_t collumn):

• Description:

  Sets the cursor position
  

• Arguments:

  1. row (0 or 1)
  2. collumn (0 to 40)
  

• Return value: void:

  none
  

void LCD_write_string(char* string):

• Description:

  Writes string of characters to the display
  

• Arguments:

  1. pointer to the string
  

• Return value: void:

  none
  

void LCD_write_buffer(char* buffer, uint16_t length):

• Description:

  Writes buffer to the display
  

• Arguments:

  1. pointer to the buffer
  2. length of the buffer
  

• Return value: void:

  none
  

void LCD_pulse_en():

• Description:

  Pulses the EN pin of the display 
    1. pulls the pin HIGH
    2. waits specified amount of microseconds (LCD_DELAY in HD44780/HD44780.h)
    3. pulls the pin LOW again
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_pulse_en_repeat(int repeat):

• Description:

  Calls LCD_pulse_en() specified amount of times
  

• Arguments:

  1. amount of times to repeat
  

• Return value: void:

  none
  

void LCD_show_cursor():

• Description:

  Turns on cursor on the display
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_hide_cusror():

• Description:

  Turns off cursor on the display
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_on():

• Description:

  Turns on the display
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_off():

• Description:

  Turns off the display
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_cursor_blink():

• Description:

  Turns cursor blink on
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_cursor_noblink():

• Description:

  Turns cursor blink off
  

• Arguments:

  none
  

• Return value: void:

  none
  

void LCD_home():

• Description:

  Sets cursor to the home position (0, 0)
  

• Arguments:

  none
  

• Return value: void:

  none
  

Resources:

• HD44780 datasheet
• Guide for communication