Newbie: Writing to 634 LCD


New member

I am working on a project using java and am interested in using a USB port LCD 634. I've never worked with an LCD display before, and know that Java doesn't have an api that supports communication with USB yet.
What I'd like to know is how you communicate with the LCD once the driver is installed. All I need to do is send text messages to the display from my program. I want to make sure I'm going to be able to utilize the display for my project before I purchase it. Thanks in advance.
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
Last edited:
USB LCD Displays - Graphic and Character LCDs with a Keypad


New member
Even though it is USB the driver makes it a virtual COM Port. You can find out what COM port it is using via the Device Manager under Ports. I have written a method to do it programmatically in VB by Enumerating the Registry. I get it from HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\FTDIBUS\VID_0403+PID_FC09+CFB6X90MA\0000\Device Parameters\PortName

You can’t just point your code to there, as the driver version could change. So I Enumerate HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\FTDIBUS getting all the different Key’s to see which one has Mfg is equal to Crystalfontz.

This might be more info then you’re looking for, but this should give you an idea. On how to find the port you want to talk to.

To talk to the ports and send it commands is easy. There is complete documentation on what control codes to send to the device.

All the details with control codes.

Page 4 has the goodies.