LCD Module to PC Parallel Port Information

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CF Mark

Disclaimer: We do not recommend connecting CFAH* series character LCD modules, CFAP* PLED/OLED modules, CFAG*/CFAX* series graphic LCD modules, CFAL series OLED graphic modules, or CFAF series TFT graphic modules to a PC's parallel port as an "end product". These displays are not "user friendly" and connecting them to a PC's parallel port is often difficult, frustrating, and can result in a "dead" display due to mishandling. These displays are intended to be designed into a finished product by an engineer--they are not designed to be a PC accessory.

That being said, there will still be plenty of hardware hackers that will do it because it can be done, and connecting the display to a parallel port can be a handy way to test or evaluate the displays. While we do not offer support for connecting these displays to a PC's parallel port, if you have decided to take the risk and do it anyway, here we do think that this utility will make the task of debugging your circuit much easier. Use at your own risk--this is entirely unsupported software.

You will have to, or you already did agree to our policies when you placed your order:

We will not support modules connected to a PC's parallel port by phone or e-mail. We will not repair or replace modules that have been connected to a PC's parallel port. You can read this forum, which is sure to have a lot of good information in it. If you cannot find the answer here, you can post a question here, and it is very likely that someone will answer the question.

OK. Now that you know where we stand, here is some information that may help you if you decide to ignore our warnings and continue on your perilous journey.

Some things to keep in mind:

#1) These modules are 100% tested. The module you had in your hand when you first opened the box was a working unit. If it stops being a working unit, something traumatic has happened to it when it was in your hands.

#2) The power supply in a PC is incredibly powerful. The modules are not. If you connect power from the PC to the module and get it wrong, the module will not stand a chance. Be 100% sure of your power connections before you connect. You will not get a second chance to hook it up correctly.

#3) 99% of the troubles involve wiring problems. If it does not work, it is your wiring. Let me say that again. If it does not work, it is your wiring.

#4) For LED backlights, you always need a current limiting resistor. This fixed resistor will be in addition to a dimming potentiometer if you use one. See the thread on backlights here.


CFAH* parallel port test program (Source included, not supported.):

CFAG* parallel port test programs (Source included, not supported. These programs are very rough, and may have incomplete or incorrect comments in them. They worked when we zipped them.):


Third-party software for graphic LCDs (powerlcd is not there anymore):

Links to third-party software:

Third-party guides:

-CrystalControl/CrystalControl2 supported wiring guide (non 40x4).
-CrystalControl/CrystalControl2 supported wiring guide (40x4).
-Overclockers Australia guide.
-Guide by Michael Sobik.
-IceHardware guide.
-EE Compendium.
Warning: The ModdersHWQ guide has no backlight current limiting resistor, and will ruin the backlight in your LCD.
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
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