A. Connection diagram of a LCD module |
This is the original description by Nils Färber from src/lcd/lcd/driver/README. I adjusted the drawing to clarify the short cut between terminals 5 and 1 on the LCD module.
--------------- snip ----------------- 25 pole LCD SUB D Panel Pin --------------------------- 18-25 GND --+ GND 1 --+--- \ Connect to R/W 5 --+ +5V 2 ------ / Gameport 1 EN 6 2 DB1 7 3 DB2 8 4 DB3 9 5 DB4 10 6 DB5 11 7 DB6 12 8 DB7 13 9 DB8 14 14 RS 4
Pin 3 on the LCD is the LCD driver control voltage input, i.e. contrast regulation. My display shows very good contrast when wired directly to GND. Other display may need a real driver current. You can use a variable resistor (>= 20 kOhm) to do it like this
+5V ---+ / \ <--+ / | \ | GND ---+ +--- VL (Pin 3 - driver input)
The PC game port offers several +5V lines that can be used as power supply. You can use
DB15 pins 1,8,9 or 15 for +5V 4,5 or 12 for GND
But please try to verify this for your hardware because some soundcards may carry additional signals like a Midi port on those lines. A floppy or harddisk power connector serves also as power supply. Here use the red wire (+5V) and the black wire (GND). CAUTION: The yellow wire carries +12V which would toast your display immediately and may also damage your parallel port!
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