Sharp 4LU4E LCD interface board

 

 

 

 

The Sharp 4LU4E is a 4" LCD panel with built-in NTSC and RGB video interfaces. It has a 28 pin Flat Flex Cable (pitch is 1mm) interface. I got my unit at weirdstuff.com and it had the flex cable attached.

 

After a lot of searching, I found the Sharp 4LU4E datasheet on a Chinese website (now gone).

 

The interface to this LCD is relatively simple, as long as you have an NTSC signal. The LCD needs 2 separate 8V regulated voltages, one for the control electronics, one for the backlight. According to the datasheet, these should be separately regulated supplies.  To use the RGB interface, the LCD requires a analog RGB signal at 15.7 KHz. Older CGA graphics computers and game boxes used to generate a digital RGB signal at this frequency (0 or 5v so they may work). Apparently the TRS-80 Color Computer 3, Commodore Amiga and Atari ST (maybe others too) generated an analog RGB signal at 15.7 KHz.

 

I also added the proper resistor divider chains to control Brightness, Color, Tint and Dimmer.

 

The image you see on the screen was generated by a Magnavox TB100MG9 HDTV converter using a rabbit ears antenna. These devices are perfect for generating NTSC test signals.

Next I created a circuit using Cadsoft's Eagle PCB design program and sent it to BatchPCB to get a real board. This board uses the Molex 52207-2885 ZIF FFC connector which fits perfectly with the flat cable. Here is the zip file containing the Eagle design files (schematics and board, as well as the Gerber files suitable for BatchPCB. They are somewhat unusual in the sense that the bottom files (solder side and solder mask) are not mirrored.

 

Unfortunately, I selected an incorrect component for the VGA connector so I have not tested the RGB interface yet. This will be fixed in the V2.

Also, this RGB interface will only work for NTSC frequency (15.734 kHz). Most computer generated RGB signals (VGA and better) are too fast for this display. The video signal generated by the uzebox project works perfectly on this display.

 

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