Display through colored transparent plastic


New member

I am curious about which display I should get to be able to efficiently display through 1/8" colored (red) transparent plastic. Currently I am using a CFA632-YFB-KU display and am planning to upgrade to a 20x4 USB display. The current display requires 100% brightness and 70% contrast to show up okay through the plastic. The continuous use of the brightness that high seems to be putting a strain on the display (after about a month the brightness now has a minor unevenness across the display).

Is there a better choice for displaying through this material?
How about the backlit, yellow text on black? Would the "FSTN Positive" and "STN Negative, Blue" make a difference? (what exactly does that mean?)

Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.


New member
Those do look really clear with no bleeding of the background and the red text would obviously shine through the plastic.

Although, as you mentioned, using them is a big step up from a USB connected display controlled through LCDSmartie.

First is the question if I would be even able to connect it to my motherboard, which has the potential connectors:

  • GPIO (8-bit): Digital I/O connector. Pins: 8 for I/O, 2 grounds, VCC, and +12V.
  • IrDA: Supports SIR. Pins: VCC and Ground, IRRX, and IRTX
  • RS232/422/485: Standard serial/COM port header.

Which of these is possible to control the LCD with?

How easy is it program each one? (I am comfortable with C programming and system calls).

Will I need special drivers to be able to communicate with it? Or how do those GPIO and IrDA ports work? (I just barely get how COM ports work so bear with me...). (I would need this to work in Windows at the moment, but Linux probably one day).

Can any of these provide the necessary power for the backlight? (Obviously not the COM, but the IrDA and GPIO both seem to have some voltage associated with them). Otherwise I guess I would solder on a cable to attach to the molex connectors from the power supply (I am doing something similar for another little thing in my custom case).

Are there any 4 line models of these nice red guys?

If I can't get this to work I may just cut a hole out for the LCD, but the front of my case won't be awesomely flush or have a consistent color scheme.

CF Tech

Connecting these to a parallel port is possible, but can be difficult, please refer to this thread:


We do not have a 4-line red display that is FFSTN.

As far as software, what do you want the display to do? For general system monitoring there is CC2, LCD Smartie etc. Do you need to do something specific?

If you really want red, possibly the best option we have is the CFA-631:

That is going to be easier on the software and interface side of things. Could your design use an LCD in a 3.5 drive bay?
Last edited:


New member
I did find an interesting page on how to make a USB controller for any HD44780 compatible LCD:


It uses the 4-bit system. I do have some experience with electronics, and have a number of friends who would be able to help me as I work on that. The USB controller is then completely compatible with LCD Smartie (and all the other software packages). It even does backlight control. I also would probably have quite a bit of fun building it.

I am building a completely custom case and have no space for something the size of a 3.5" bay, nor do I have any need/want for the buttons.

The reason for red is it will be displaying through red, and hopefully transmit more effectively through red then does the yellowish color of the current module. The flush front of the case is a very nice effect.

So the question I need to answer is:
Should I get the 20x2 with FFSTN or the 20x4 with just STN (http://www.crystalfontz.com/product/CFAH2004A-RMI-JT)?

That pure black background is quite nice. I think I am leaning towards that option.

CF Tech

Maybe 2 pieces of 20x2 FFSTN?

I think the 20x2 FFSTN looks enough better that I would choose it over the 20x4 STN.


New member
Yeah. It does look really clear. For now I will just go with a single 20x2 display.

One question I have about it though. As I have been designer a controller for it, I am confused by the backlight pins for CFAH2002Y-RDI-ET. There are two sets of pins, and the numbering for them is weird. Do I have to apply 5V to each set of pins, or will one set suffice? What would happen if I applied different backlight "settings" (PWM) to each?