Here I will describe how to make your own parallel to LCD circuit. It is a fairly simple process. I have also included a schematic of the circuit, I will explain how to read the schematic below. If you have any question's or comments, or find this tutorial usefull.. let me know... magikh0e A.T ihtb d0t org. - IHTB
h0eLCD Schematic - PNG - Eagle SCH Format
Reading the schematic is moslt fairly simple, some of the confusingness may be cause by the wire layout. A simple connected wire looks as follows
. UnConnected wires that may cross & not connect will look like
. Molex connector:
Note: Do not follow the picture much as far as what goes where, I did things a bit backwards from the instructions, specifically the pic shows reversed 5v+ and 5v-.
Part's needed:
1 Paralell cable - Use any old printer cable, just chop the end off the plugs into the printer.
1 LCD - I used a 2x16 HD44780 compatible LCD 1 100 ohms resistor 1/4watt 1 10k potentiometer (optional) 1 male DB25 connector 1 male molex connector, I used a 3 prong y-splitter molex cable. Multimeter (optional, makes life much easier (; ) Tape and/or Shrink tubing
Now that you have all the required parts, it is time for some hax0ring. Begin by chopping off the printer plug end of your parallel port. I did the pain staking way of mapping out the pins and cables by using the multimeter to test connectivity.
I suggest that you wire each end by hand, this will be much easier especially if you do not have a multimeter...
Step 1: Take your male DB25 connector and solder some 22 or 24 gauge wire to pins 1 through 9, 14, 16 and then 18 through 25. Note: If you are making your own cable make it long enough to reach where you wish to install it. If you are using a printer cable that you chopped up, use the multimeter to find the correct wire for each pin. Step 2: Once you have soldered on all of your wires to the correct pins, double check your work and then we can proceed to connecting them to your LCD display. Step 3: Take the wires from pins 1 through 9 of the DB25 connector, and solder them to pins 6 through 14 on the LCD. Refer to the schematic or your LCD's data sheet for the proper pin layout. Step 4: Remove the yellow & black wire next to it from the molex connector. Wrap these up with some tape or shrink tubing so no wires are left exposed. Step 5: Use the top left mounting hole for your 5v+ source. The top right mounting hole wille be for the ground. IMPORTANT Note: make sure you use the RED 5v+ wire from the molex connector into the 5v+, if you use the yellow wire say goodbye to your LCD (;. Now connect the black wire to the ground mounting hole. Step 6: On the LCD solder a wire from pin 2 then connect connect it to the left mounting hole for 5v+. The solder a wire from pins 1 & 3 and connect them to ground. Step 7: Almost there! Now take all of those wires from the DB25 connector pins 19-25 and twist them all together really tight. The wrap another single wire and solder or crimp them together, solder this single wire into the right mouting hole for ground. Step 8: On the right side of the LCD there is 2 small pin's. Some are labeled A/C, others A/K. Connect C or K with a 10ohms resistor into ground. Step 9: Connect a wire from A into the left mounting hole for 5v+. Step 10: Tape all the wires up so there is no exposed wiring, power down your computer and connect up to the power supply and the parallel port. If all goes well when you power your computer on, the LCD screen lights up and display's a series of boxes.
- Mods - Adjustable Backlight Brightness: This can be accomplished by replacing the 10ohm resistor from pin 16 of the LCD with a variable resistor 'potentiometer' Adjustable Contrast: This can be accomplished by using the optional 10k variable resistor 'potentiometer' to pin 3 of the LCD.
- Software - lcd4linux - http://ssl.bulix.org/projects/lcd4linux/"> lcdproc - http://lcdproc.org/