ATMega8 driving HD44780 LCD

Baby steps here folks. I've just got my Atmel ATMega8 to drive an HD44780 LCD using the 4 bit parallel interface. (Previously I've been using a serial interface which is much simpler).

All the heavy lifting is done by AVRlib, a great library with lots of helpful libraries for driving external hardware.

Beware, there is a very similarly named library AVR-Libc, which also looks good.

I'm driving the LCD in "Port interface" mode and using the 4 bit data mode. As speed isn't important for my application I've chosen to save the extra 4 dataport pins.

Here's my config from lcdconf.h:

#define LCD_PORT_INTERFACE

// Enter the parameters for your chosen interface'
// if you chose the LCD_PORT_INTERFACE:
#ifdef LCD_PORT_INTERFACE
	#ifndef LCD_CTRL_PORT
		// port and pins you will use for control lines
		#define LCD_CTRL_PORT	PORTD
		#define LCD_CTRL_DDR	DDRD
		#define LCD_CTRL_RS		2
		#define LCD_CTRL_RW		3
		#define LCD_CTRL_E		4
	#endif
	#ifndef LCD_DATA_POUT
		// port you will use for data lines
		#define LCD_DATA_POUT	PORTD
		#define LCD_DATA_PIN	PIND
		#define LCD_DATA_DDR	DDRD
		// access mode you will use (default is 8bit unless 4bit is selected)
		#define LCD_DATA_4BIT
	#endif
#endif

My wiring for the pins on the LCD circuit board is as follows:

1. Vss 0V


2. Vdd 5V


3. Contrast Pot 10K wiper


4. RS - C2


5. R/W - C3


6. Enable - C4


7. D0 No Connection


8. D1 No Connection


9. D2 No Connection


10. D3 No Connection


11. D4 - D4


12. D5 - D5


13. D6 - D6


14. D7 - D7


15. No Connection


16. No Connection

Many thanks Pascal Stang!