Arduino Video Display Shield

An Arduino video display shield with integrated framebuffer and analog video output.

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This Arduino shield will make an end to your 1st project being an LED to be flashed. Now you are able to connect a display (which we are all hooked to anyways) and generate a virtual LED that is going to blink in every color you have ever dreamed of.
Now seriously, the Arduino family of compatible boards is lacking a solid hardware support option to display images, animations or video. This board provides an analog composite video display with integrated frame buffer memory accessible through SPI or parallel bus. It will not display 4K video but somebody will hack it to run Doom, Joust or Ultra-Cricket. PAL, NTSC and VGA output formats are supported, resolution is up to 640x480 with reduced color count.
Design data will be published once I have a working prototype, I believe open source can only win if a certain level of quality is present. There are too many projects of unknown state dumped into repositories all over the place.

The heart of this design is the VLSI VS23S010LC-L chip. It is a 1 Megabit SPI SRAM with Serial and Parallel Interfaces and Integrated Video Display Controller, which outputs a composite video signal.

Possible video resolutions, PAL and NTSC modes might be exclusive depending on the mouted crystal (4.433618MHz or 3.579545MHz):

The chip has a 3.3V interface, so a level shifter logic is required, which is done by a MC74LVX50 buffer, which is able to handle SPI Mbps speed better that a simple FET based level shifter. A 512Kbit EEPROM for bitmaps and character memory is added, but is probably too slow for effective operation. On a suggestion of [kbdhog] the next version will have a SPI flash chip for speed and memory size. Now I am dreaming of SPI DMA, which just gave me an idea of a small PLD and a parallel flash memory to implement that.

A video opamp is available for improved signal strength when a longer cable is used, but might be bridged for testing purpose.

The circuit on the bottom left of the schematic is used to fill the 10cm x 10cm PCB space and left to the reader to figure out its functionality. ;-) I will end up with ~780 copies of this circuit which will last a lifetime or they might show up on Tindie.

  • 1 × VLSI VS23S010-L 1 Mbit SPI/8-Bit Parallel Bus SRAM with Video Display Controller
  • 1 × TI OPA362 Video op-amp
  • 1 × NCP1117-3.3 Linear voltage regulator 3.3V out
  • 1 × 24C512 I2C EEPROM 512Kbit
  • 1 × 74LVX50 Hex driver non-inverting 5V tolerant inputs

View all 10 components

  • 2 Prototypes

    MagicWolfia day ago 0 comments

    2 boards are populated with all components (except the Arduino headers on one of them). One is build up with PAL crystal, the other with a NTSC version. Also only the PAL version has the additional video driver installed, it is just bridged on the other board. Initial test showed the 3.3V power rail OK and no smoke got released.

    Things to note:

    • The KiCAD Arduino shield footprint has connector through holes that are very small for regular pin headers. I almost got a press-fit connection. The extra long female headers have thinner pins and are OK.
    • All other footprints that I grabbed from the KiCAD libraries turned out to be correct (maybe I was just lucky ;)
    • Testpoints are very helpful.
    • I like silkscreen that is large enough to read without microscope.

    Now the programming begins, SPI communication first and then configuration of the video output. Then the fun starts with image display functions and porting Doom. 

  • PCBs are in

    MagicWolfi05/28/2017 at 01:50 0 comments

    Finally the bare PCBs arrived from DirtyPCBs today. This time it took the full 8 weeks, which is OK. That is what they say with the slow shipping order. The quality is very good as usual. They even managed to put a solder dam between the pads of the 0.5mm QFP footprint. This will make hand soldering super simple. And they do panels if you put multiple designs on the board by yourself. They do nice thin slots and next time I will try mousebites for even easier separation. Now I am off to the soldering iron.

    The little board is an in-line current source (* 78), which will be documented in its own project.

  • Todo list

    MagicWolfi05/07/2017 at 16:51 0 comments

    As the project page does not have a Todo list feature, I will try to "re-use" a project log for this. Starting now and editing later:

    - Add 3D models for missing components in KiCAD design (RCA conn, SOT23-6 opamp,HC49 crystal)

    Rev 02:

    - Add SPI flash

    - Add some LEDs (power rails, monitor detect, SPI activity)

    - Add button or jumper to enable test mode

  • Virtual debuging

    MagicWolfi04/17/2017 at 02:12 0 comments

    If you look at things long enough, mistakes get noticed. I just updated the schematic with a 512Mbit EEPROM (not a bug) and replaced the 74LVC07 driver with a 74LVX50. The LVC07 would have the 5V tolerant inputs for the signal from Arduino to the video chip which I was looking for, but is an open-drain driver which does not really help with SPI signals. So I replaced it with the 74LVX50 which has the same package and pinout. Easy fix when the parts are not ordered yet.

View all 4 project logs

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kbdhog wrote 04/11/2017 at 14:03 point

If I may offer a little idea: Since you already have SPI driving this board, perhaps add a nice sized SPI-flash chip (2mbits?). This can be used to store character fonts, icons, even entire bit-maps. Thereby removing that storage burden from the Arduino's memory space. The SPI-flash would be loaded once (via RS232 serial commands?) and then maybe you can have a write-protect jumper as well... making the contents somewhat "permanent".

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MagicWolfi wrote 04/12/2017 at 21:17 point

Thanks, kdbhog. The I2C EEPROM on the board was planned to be for this purpose, I just used a small 24c 64 as placeholder, the biggest I can use is a 512Kbit. You are absolutely right, an SPI flash chip would give much larger storage and higher performance. I will add this for the next rev. Boards should arrive in 2-6 weeks, stay tuned, there will be updates. Cheers

  Are you sure? yes | no

kbdhog wrote 04/11/2017 at 02:38 point

Very often, 640x480, or NTSC/PAL, are *just enough*. Especially for diagnostic screen output, or simple control systems. I like it! I look forward to seeing this work.

  Are you sure? yes | no

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