FPGA Driver For PSP Screen

Friends are constantly giving us their old electronics. We love it because our junk box is a never-ending pile of possibilities. We’re really starting to amass a collection of LCD screens that are not easily interfaced and this project gives us some hope for the future. [Philip] has been posting about using an FPGA as a driver for a replacement PSP LCD screen.

Many projects source cell phone LCD screens that have their own driver chip that can be addressed over SPI for use with a simple microcontroller. More complicated screens need a more involved control scheme and this is where the Field Programmable Gate Array takes over. [Philip] lays out the steps he’s using to implement his controller, from setting up the correct voltage levels, to planning for coordinate addressing, and even some of his follies with reverse current. We think this would be a great way to introduce yourself to FPGA projects.

20 thoughts on “FPGA Driver For PSP Screen

  1. seems complicated. i dont understand why they dont just build the screens with a vga/hdmi/dvi interface. considering how most laptops have a vga port too, the must have a controller. if the screen were a vga interface, they could use alot less circuitry and lower the cost.

  2. @googfan: I think you’ve hit on the exact reason why they use a non-standard interface: it’s cheaper. On this screen, for example, if you read part 2 of series 1, you’ll see that the interface is just about the cheapest digital interface for video you could imagine including the following parallel signals: Red(8), Green(8), Blue(8), clock(1), vsync(1), hsync(1), screen on/off(1).

    The VGA spec includes decoding analog voltages into colors, which would involve some ADCs on the screen side. The DVI spec would require using differential signaling at a much higher clock rate (read more sophisticated electronics).

    In addition, you couldn’t simply reuse the DVI or VGA driver you have on your laptop. You’d need a second or else you could only use one display at a time. If you’re adding a second driver chip, you might as well optimize your chip to send data making your screen as cheap as possible to manufacture.

  3. @tw

    yes, i think you could re-use the driver because for most consumers, all they want is an output to an external display. they normally don’t want an “extension” of their desktop. that really wouldn’t make sense for a laptop because you’d have to carry around another monitor…

  4. @googfan

    Why would you use an analogue *legacy* interface for a display that is a: natively digital b: doesn’t require to be driven by hardware with such an interface. Also do you realise how expensive high speed ADCs/DACs are? I doubt there would be any cost lowering from using VGA on a display that doesn’t CRT type technology.

    About running displays in parallel.. if the display is “dumb”, i.e. it just sits on the bus, reads what’s there, and sticks it on the display there’s no reason why you couldn’t have two displays sitting on the same bus and displaying the same thing. You would have problems with displays with an embedded controller because the communication is two-way,.. but you could probably fudge that too if you tried.

    @anyone who cares

    You probably don’t need an “FPGA” to drive a PSP screen, you could probably get away with a micro that has enough pins and a fast enough clock to throw pixel data at the screen.. preferably a micro with some external address/data bus exposed so that you can add some cheap ram for your display data. Using an FPGA is nice though because you can build yourself some really nice custom “hardware” like in the good ole days of the Amiga etc.. though you could just drive the display with the PSP :/

  5. I’ve been using the USBD480 from lcdinfo.com, a FPGA driven PSP screen with though panel for over a year now. This display is capable of 90fps (16bit) too. Few pics here: mylcd.sourceforge.net/libmylcd/usbd480/ and program snapshots: mylcd.sourceforge.net/lcdmisc/

  6. This page kinda seems like amateur hour from what I can see. The backlight circuit is lousy.

    I’ve done FPGA-LCD a bunch of times, so maybe I’m jaded, but there’s also too much basic electronics stuff.

    As far as driving a PSP screen, it’s pretty easy (LV TTL parallel data and syncs) and the best choice is probably one of the many ARM based SoCs with LCD screen driver outputs (Freescale i.MX, Atmel AT91, Marvell PXA, TI OMAP, etc). These have dedicated screen DMA hardware and no need to mess with FPGA.

  7. I’m new to this site, and this project interests me, but I cannot figure out how to see the actual project. All I can see is the comments….

    Can someone give me a one-time boost?


  8. Is this project dead too? I noticed the blog is now locked down as well Joe.

    I really want to create some sort of handheld device using the PSP screen but the 30-pin close pitch connector scares me.

    A breakout or FPGA driver board would be amazing…

    Anyone with news or related projects please leave a comment.

    — Rob R.

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