LCD  1.0
HD44780 compatible lcd driver for Xmega devices
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LCD Documentation


This documents the lcd library to use HD44780U-based text displays with Atmel Xmega devices. This library is based on the lcd library from Peter Fleury ( for the ATmega devices.

This library is suitable for four different io modes:

There are defines for these four modes:

In 8 bit mode all 8 data pins must be connected to one 8-pin port of the Xmega. In 4 bit mode all 4 data pins must be connected to one port of Xmega, but the 4 data lines may be connected to any pin of that port and in any order. The header file lcd.h contains macro definitions that can be for that purpose.

The control lines RS, E and R/W can connected to any pin of any port of the Xmega.

Be careful using the busyflag. Most alfanumeric displays are 5 Volt devices. Xmega's are not 5 Volt tolerant. When using the busyflag, information is also send from the LCD to the Xmega. So you can damage your Xmega.


To use this lcd library:


Wim Dolman (
Latest version can be found here:


This library is free software. You can redistribute it and/or modify it. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY.