Since my server does not have a monitor, I wanted to connect an LCD. At the parallel port it is quite easy; however, an extra power supply would have been necessary, and so I came across the LCD2USB interface by Till Harbaum on the Internet. The server runs Linux and LCDproc supports this interface without any problems. I found all necessary parts in my tinkering box.

First, all components were mounted on a breadboard:

During the test run, there were some problems. The display needs a negative contrast voltage (like all LCDs with extended temperature range). Fortunately, the contrast voltage from the Atmel is regulated by PWM. So I could build a small charge pump which produces about -4 volts:

Links for the project

• Original schematic
• Link to the original website
• LCDproc website

Last update: October 2011