james1095

Driving small TFTs

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This has been discussed in the past but recently I came across a nice little 4:3 aspect ratio QVGA TFT which is very easy to use with just about any FPGA project that produces a roughly SD-TV resolution image, ie most early arcade games and 8 bit computers. This is the LQ035NC111, an older but still fairly widely available display which uses a parallel RGB-dotclock interface that does not require any type of initialization sequence to work, shown here running PacMan from fpgaarcade. These displays are nearly perfect for this application due to the 4:3 aspect ratio and resolution conveniently close to most classic arcade games, they're commonly used in those cheap backup camera monitors from China. The modifications to the code are very simple, all you need to do is feed the 6MHz ena_6 to the DCLK pin, reset_h to the reset pin and RGB/Hsync/Vsync to their respective pins then tie the unused RGB inputs to ground. The photo looks really washed out but in reality the display looks quite nice with good color and reasonable contrast. The only small hassle is that these displays have no built in backlight driver so you need a boost converter capable of producing about 20V and driving 10-20mA for the LED string. I lashed it all up with an ebay breakout board but eventually I'll make something more permanent. The plan is to scale down the plans and build some tiny desktop arcade cabinets but it could also be used to build a handheld or desktop version of virtually any game, console, computer or other application that fits in the FPGA and produces a video signal.

 

If anyone hooks one of these up and has difficulty getting it going I'd be happy to help.

arcade tft

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