LCD unit driven by a computer parallel port

From uCtrl
This page is kept for historical interest. It may document projects or methods that are obsolete and/or no longer relevant. The information here is not kept up-to-date.

I'm not using this module anymore, there are much easier ways to connect an LCD these days.
PLD on top of the TV

Information

Very simple module connected directly to the computer parallel port. The LCD display is powered by 5V, and has and internal fuse. The backlight is lit constantly. The contrast can be regulated with the variable resistor. The LCD display is driven and controlled by LCD Smartie, multiple screens alternate to show more information then the display can fit. I use it for song played on the computer, temperatures, voltages etc.

I/O

LCD pin Name Description Centronics pin DB25 pin
1 Vss GND 19 Arrow right.png 30 18 Arrow right.png 25
2 Vcc 5V n/a n/a
3 VLc Contrast (to a 10k variable resistor) n/a n/a
4 RS Register Select 31 16
5 R/W Read/Write (to GND) n/a n/a
6 E Enable 1 1
7 D0 Data 2 2
8 D1 Data 3 3
9 D2 Data 4 4
10 D3 Data 5 5
11 D4 Data 6 6
12 D5 Data 7 7
13 D6 Data 8 8
14 D7 Data 9 9
15 VB+ Backlight (120 ohm to 5V) n/a n/a
16 VB- Backlight (to GND) n/a n/a

Images

Screen shots

Schematic drawing

Parallel-port-to-lcd-circuit-v4lkpq.png

Parts list

Qty. Part
1 Capacitor, aluminium electrolytic, 10 µF, 25V
1 Capacitor, aluminium electrolytic, 47 µF, 25V
1 Capacitor, ceramic, 1 nF, 100V
1 Capacitor, metallized polyester foil, 0.01 µF
1 Centronics, chassi, 36-pin
1 Enclosure, plastic (Alu. lid), 110x70x49mm
1 Fuse 5x20 mm, 200 mA, fast-acting
1 Fuse holder, open, PCB, 5x20mm
1 Fuse holder, open, PCB, Protective cover
1 LCD display, dot matrix, 16x2, LED green
32 cm2 PCB, stripboard, 100x160mm, 160cm2
1 Power jack, panel, 2.1mm, plastic housing
1 Resistor, carbon film, 0.25W, 120 Ω, 5%
9 Spacer, round unthreaded, 3mm, Ø6mm, Delrin
16 Straight pin header, female, Single row, 2.54mm
16 Straight pin header, male, Single row, 2.54mm
1 Trimmer, carbon, 10 kΩ, horizontal

Resources