Breathing life into an old LCD

panel

Out of the depths of a junk drawer, [Alex]’s friend pulled out an old monochrome LCD display. This is an older low-resolution display from ancient electronics that unfortunately doesn’t have its own controller chip. No worries, though, because with the help of an FPGA [Alex] figured out how to drive this display.

On the back of this display are eight Hitachi LCD drivers, six column shifters and two row shifters, allowing the LCD to display a 256×128 pixel image. Without an LCD controller, though, [Alex] couldn’t just send a static image to the LCD. Instead, he had to continuously refresh the display just like a VGA monitor.

With the help of a 1500-page PDF titled Hitachi LCD Controller/Driver LSI Data Book, [Alex] was able to dump pixels into the ICs on the display with the help of a Papilio One FPGA board. A lot of work just to display the beautiful [Lena], but she wouldn’t have it any other way.

10 thoughts on “Breathing life into an old LCD

  1. Good stuff! I have a couple of LCDs that I want to try this sort of thing with. One’s out of a very old, scrapped Gould instrument of some sort, and the other’s out of a Psion 3a organiser (with a broken FPC).

    1. I did something similar using a microcontroller. The trick is to use a DMA-capable SPI peripheral to send an entire frame to the display. The DMA end of stream interrupt just starts a new DMA transfer so the screen is continuously refershed.
      As the interface to those displays (at least, mine) isn’t SPI, but 4-bit parallel I used some glue logic to partially deserialize the data stream, and generate VSYNC and HSYNC.
      It’s documented here: http://www.webalice.it/fede.tft/spi_as_lcd_controller/spi_as_lcd_controller.html, and I’ve submitted it to hackaday a while ago, but for some reason it wasn’t featured.

  2. You know, I’d really like to see a tutorial or something on how to use old LCD screens for your own purposes. I’m sure we all have a lot of old cellphones lying around with perfectly useable screens in them. I can never bring myself to throw them away.

  3. Dang kids these days and their fancy FPGAs. This particular panel looks like it already has the traces for a Hitachi CPU interface controller on the back, likely an HD61830 or the like. A GWS for the driver chips yields http://mazsola.iit.uni-miskolc.hu/ftp/unix/lcddabo.pdf as the 7th hit. The chips might be hard to find but one could maybe be cannibalized, or just find a cheap 256×128 panel that already has one, they are common.

    The 61830 can be driven by a PIC or a 6502 rather than requiring an FPGA. I don’t want to diminish the hack status of this post, but it seems people these days want to just throw hardware at a problem rather than consider the original design.

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