Lcd controller; connect 20×4 character LCD to parallel port

I use the Alix-1D motherboard for embedded applications, with Puppy Linux OS and Gambas2 visual Basic IDE. It’s very easy to connect an LCD character display to the parallel port of the motherboard. There is a PIN STRIP connector, named J14, that provides all the signals for the parallel port. In my application I used the Hitachi LM044L display connected to the board in this way:

schematic diagram of display connections

schematic diagram of display connections

  • DB7..DB0 – Data bus, connected to ‘D7..D0’ of LCD
  • /STB – Strobe, connected to ‘E’ of LCD
  • /SCI – Slct-in, connected to ‘WE’ of LCD
  • /AFD – Auto-LF, connected to ‘RS’ of LCD
  • GND – Signal ground, connected to ‘VSS’ of LCD
  • The +5V supply can be taken from pin 4 of connector J15

lcd20x4picThe downloadable file puppy_gambas_lcd.tar.gz contains the whole project folder with sources for Gambas2. This is a minimal working implementation; you have two buttons on the form: the first is for display initialization / clear, the second writes an incrementing character each time you click it, every time moving to next available LCD cursor position.