[Sprite_tm] connects an LCD to a tiny Linux board

One of [Sprite_tm]‘s colleagues recently challenged him to connect a small LCD touch screen to a Raspberry Pi. Sadly, [Sprite_tm] has yet to take delivery of a Raspberry Pi, but he did manage to connect an LCD to a Linux board without video capabilities.

Because [Sprite_tm]‘s display has a 16-bit parallel interface, and 16 GPIO pins are hard to come by on the Carambola Linux board, a few shift registers had to be brought into the build to make the LCD work. These shift registers are connected to the Carambola board via an SPI interface; a very simple way to connect all the LCD pins to the Linux board.

Of course, there’s no way for Linux to speak to the LCD without a kernel driver; [Sprite_tm] wrote a framebuffer driver so the LCD can be used as a console, an X session, or used by any other program that can write to a framebuffer device.

Like all good driver authors, [Sprite_tm] is giving away the patch to enable SPI-ified LCD panels on the Carambola along with the shift register schematic. With any luck we’ll also see the Raspi drivers when [Sprite_tm] takes delivery of his Raspberry Pi.


  1. Hack Man says:

    SPI is a very simple way to connect all the LCD pins to the Linux board. It’s also quite slow, too.

    • Hack Man says:

      and that’s BEFORE the shift registers.

    • Sprite_tm says:

      Not necessarily. The SPI-interface on the Ralink-chip on the Carambola can run up to 50MHz, which is plenty quick. Unfortunately, it does seem to have a lot of overhead wrt setting up transfers, which slows down everything quite a bit… The Pi could do better there, iirc that chip can do a DMA-transfer to the SPI-interface which should be lots quicker.

  2. barryronaldo says:

    Dang SpriteTM you always rock it out! Don’t ever stop :)

  3. The Cageybee says:

    CGA FTW!

  4. ixbidie says:

    Sadly, the DSI Interface is directly connected to the GPU, which needs a binary blop to run properly since it’s closed source.

    However, the foundation plans to release a LCD display in the future so we can expect a driver then which would make it possible to use standard LCD displays for smartphones . Anyway, until this happens there is nothing to do but to wait.


  5. Josh Malone says:

    I’ve always made “Can it play Monkey Island?” my personal test of a machine’s usefulness. Very nice!


  6. deadlyfoez says:

    I LOVE the Monkey Island series. They are always comical and I will still play them over again every once in a while and find myself chuckling again. The Monkey Island series and Super Metroid are my all time favorite games.

  7. Aaron Bitler says:

    I love the Monkey Island!

  8. naturetm says:

    Sprite_tm, you’re a hack-factory. Always good stuff and in topics I’m interested in.

  9. Jeff says:

    what a great game. Back when games only had single player, they needed a great storyline. Unlike the same old Call of duty crap that comes out every year.

    You fight like a dairy farmer.

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