Just a dumb question...

Discussion in 'Embedded Systems and Microcontrollers' started by parkland, Apr 20, 2015.

  1. parkland

    Thread Starter New Member

    Dec 1, 2012

    This might sound really stupid, but I was just thinking earlier about how a monochrome laser projected display would be for certain instances.
    I was bored, and wasting time looking at youtube videos.
    Some amazing projects for sure.
    All of these raster scanning laser projector projects all have the x mirror and y mirror, spinning, to move the laser light across the screen, down a pixel, across the screen, down a pixel, etc, over and over to put the image on a screen.

    My question is this; for a simple cheap monochrome display, is there a simpler way to do this than super expensive electronics?
    Is there a chip or microcontroller that can just dump "1"s and "0"'s out a pin fast enough to support a high enough bit rate?

    For example, if the screen was 1920x1080, that would be 2,073,600 bits. At a 24 frame per second refresh rate, that would be 49,766,400 bits pushed from memory to an on/off pin every second.

    There would be a trigger from the x mirror position, so that top left corner is a fresh frame. From there, the video memory would dump the first 1920 bits, then wait for a y trigger signal that the y mirror is lined up to the left again.

    So the chip or microcontroller would hold a 2,073,600 bit video memory.
    If reset pin is set on, it would prepare to send data from memory location 0.
    If the horizontal pin is triggered, it would send 1920 bits of data to the laser. Next time the pin is triggered, it would send the next 1920 bits of data to the laser.
    So the reset pin would trigger from the vertical mirror, lined up at the top of the screen would start dumping the image data from memory location 0.
    The horizontal pin would be triggered by the mirror being lined up to the left of the screen.
    It would raster cast an image of whatever is in the memory.
    Also, the memory would need to be modified on the fly as well, without interrupting the video rendering.

    Is there anything that would do this, and for cheap?
    It's not like the world is crying for monochrome laser projectors or monitors, but I thought it could be a really fun and cheap.
  2. JWHassler


    Sep 25, 2013
    What you describe is exactly what laser projectors do, minus a few details.
    It would display a static image, which you would probably want to animate,so: more details.
    As for doing this "for cheap," that's engineering.
  3. parkland

    Thread Starter New Member

    Dec 1, 2012
    I was thinking of a display for embedded chips or electronics where a display isn't feasible or cost effective.
    I was especially thinking a high resolution monochrome display for editing text of a program.
    Cheap little LCD displays exist, High res LCD displays exist, but they are not something an average user would ever afford.
    Laser projectors also exist, but they are pricey also.
    Laser projection makes sense for an output screen on say, a robot, because it doesn't need to be focused like an LCD projector.

    I was just wondering if this is something that could be made easily, or is an extensive project.
    The reason I thought it could be easy and cheap, is that I am noticing a lot of cheap microcontrollers that seem capable of very fast speeds.
    For EG the parallax propeller.
    It seems like it would be cheap to spin mirrors, and use sensors to trigger the next frame and new horizontal line.
    I don't know what chip is capable of pushing data to a pin that fast though.
    My programming is pretty limited, basic variants. Although I have edited in a few other languages in the past to change a couple things.
    I know there are several chips and single board computers that use versions of basic, but I doubt any would be fast enough.
    It would be extra nice to have an ultra high resolution display, so lots of text can be shown.

    On one hand it sounds easy.
    On the other hand, it would have been done already if it was.
  4. JWHassler


    Sep 25, 2013
    Here's a muy-cheap ($20)ARM board : Teensy
    And here's a $5, 10-million-lines/sec Basic compiler for it : Coridium
    Still leaves a lot of details, though,