Interfacing attiny2313 AVR with HD44780 LCD

We will use an attiny2313 AVR microcontroller to display strings on an HD44780 LCD (4-bit mode).

482 bytes of flash written. Using internal oscillator.

## Connections

+-----------------------------------+----------------+
|            HD44780 LCD            | attiny2313 MCU |
+-----------------------------------+----------------+
| PIN 1 (GND)                       |                |
| PIN 2 (+5V)                       |                |
| PIN 3 (contrast/GND)              |                |
| PIN 4 (reg select)                | PIN 2 (PD0)    |
| PIN 5 (R/W)                       | PIN 3 (PD1)    |
| PIN 6 (Enable)                    | PIN 6 (PD2)    |
| PIN 7                             |                |
| PIN 8                             |                |
| PIN 9                             |                |
| PIN 10                            |                |
| PIN 11                            | PIN 12 (PB0)   |
| PIN 12                            | PIN 13 (PB1)   |
| PIN 13                            | PIN 14 (PB2)   |
| PIN 14                            | PIN 15 (PB3)   |
| PIN 15 (220 Omhs resistor to +5V) |                |
| PIN 16 (GND)                      |                |
+-----------------------------------+----------------+

## Firmware

We will include in our code the LCD library by Peter Fleury (http://homepage.hispeed.ch/peterfleury/avr-software.html#libs).

lcd.h – setting ports and 4-bit mode
line 128:

#if LCD_IO_MODE
#ifndef LCD_PORT
#define LCD_PORT         PORTB        /**< port for the LCD lines   */
#endif
#ifndef LCD_DATA0_PORT
#define LCD_DATA0_PORT   LCD_PORT     /**< port for 4bit data bit 0 */
#endif
#ifndef LCD_DATA1_PORT
#define LCD_DATA1_PORT   LCD_PORT     /**< port for 4bit data bit 1 */
#endif
#ifndef LCD_DATA2_PORT
#define LCD_DATA2_PORT   LCD_PORT     /**< port for 4bit data bit 2 */
#endif
#ifndef LCD_DATA3_PORT
#define LCD_DATA3_PORT   LCD_PORT     /**< port for 4bit data bit 3 */
#endif
#ifndef LCD_DATA0_PIN
#define LCD_DATA0_PIN    0            /**< pin for 4bit data bit 0  */
#endif
#ifndef LCD_DATA1_PIN
#define LCD_DATA1_PIN    1            /**< pin for 4bit data bit 1  */
#endif
#ifndef LCD_DATA2_PIN
#define LCD_DATA2_PIN    2            /**< pin for 4bit data bit 2  */
#endif
#ifndef LCD_DATA3_PIN
#define LCD_DATA3_PIN    3            /**< pin for 4bit data bit 3  */
#endif
#ifndef LCD_RS_PORT
#define LCD_RS_PORT      PORTD        /**< port for RS line         */
#endif
#ifndef LCD_RS_PIN
#define LCD_RS_PIN       0            /**< pin  for RS line         */
#endif
#ifndef LCD_RW_PORT
#define LCD_RW_PORT      PORTD        /**< port for RW line         */
#endif
#ifndef LCD_RW_PIN
#define LCD_RW_PIN       1            /**< pin  for RW line         */
#endif
#ifndef LCD_E_PORT
#define LCD_E_PORT       PORTD        /**< port for Enable line     */
#endif
#ifndef LCD_E_PIN
#define LCD_E_PIN        2            /**< pin  for Enable line     */
#endif

and in line 241:

#define LCD_FUNCTION_8BIT     0      /*   DB4: set 8BIT mode (0->4BIT mode) */

main.c:


/* dthlabs.com - July 22, 2017 */

#define F_CPU 1000000  // CPU frequency
#include <stdlib.h>
#include <avr/io.h>
#include <util/delay.h>
#include "lcd.h"
#include "lcd.c"

int main(void) {
  lcd_init(LCD_DISP_ON);
  lcd_clrscr();
  lcd_puts("   dthlabs.com\n");
  lcd_puts("    tech blog");
}

github repo: https://github.com/xdth/AVR_HD44780LCD

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