ATmega8 and 2×16 HD44780 LCD

Following my first article on the initial findings and results of my tests on the ATMega8, this article will show basic steps on how to connect a 2×16 characters LCD to the micro chip.

The reason for this is to have a way of debugging the microchip functionality, to output the results, the data and various other stuff. I can tell you this is a must have.

To use a minimum of I/O pins, I’ve decided to build a 4bit interface with the LCD. The hard part was to write the code, but finally after fixing several bugs and reading a lot of HD44780 documentation, I can say that I’ve completed a nice flexible code – meaning that you can easily configure the LCD pin connection.

The wiring diagram is below:

The code interface is also attached, not much to say about it here, since it’s full of technical details and bit-wise operations, but if anyone has questions feel free to use the comments form at the bottom.
To edit some parameters like frequency or PIN connections (you can change the I/O pins used by the LCD on the ATMega), have a look in lcd.h . Zip attached:
atmega8-lcd

Function lcd_string2 is very useful for outputting text, since it supports variable parameters similar to printf. So you can use it for outputting misc content: lcd_string2(“Hello World! %d\npocketmagic.net”,i);

Here are some pictures with my LCD running:

Next thing to do is to start connecting various sensors.

Radu Motisan