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https://github.com/ZipCPU/vgasim

A Video display simulator
https://github.com/ZipCPU/vgasim

fpga gplv3 gtkmm verilator verilog vga video video-simulator

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A Video display simulator

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README 

        
## Controller



This repository contains a couple of [Video Controller](rtl/wbvgaframe.v)s.



The original [Video Controller](rtl/wbvgaframe.v)

includes not only the [low-level framer](rtl/llvga.v), but also

a [bus controller](rtl/imgfifo.v) to read values from memory to then be

displayed on the screen.  This is the basis of a frame buffer approach to

video.  This capability is fully demonstrated via the [Verilator

based](http://zipcpu.com/blog/2017/06/21/looking-at-verilator.html) simulator.



There are now also two AXI-based cores.  The first is an [AXI-based Video

Controller](rtl/axivideo.v) that can produce either VGA or HDMI signals.  This

controller is demonstrated via a [slightly different

simulator](bench/cpp/axi_tb.cpp), including simulations for both

[VGA](bench/cpp/vgasim.cpp) and [HDMI](bench/cpp/hdmisim.cpp).

The [second AXI-based video controller will record incoming video signals to

memory](rtl/axicamera.v).  The incoming capability is [demonstrated via

a simulation](bench/rtl/axirepeater.v) to capture a piece of your screen via

an [HDMI source simulator](bench/cpp/hdmisource.cpp), [write it to an AXI-based

block RAM frame buffer memory](rtl/axivcamera.v), and then to [read it back out

again](rtl/axivdisplay.v) to feed a GTK++ window.



## Simulation



This repository also contains two basic [video simulator](bench/cpp/vgasim.cpp)

components.  The first, either [VGASIM](bench/cpp/vgasim.cpp)

or [HDMISIM](bench/cpp/hdmisim.cpp) takes video outputs from a

Verilated [design module](bench/rtl/demo.v) and displays them on your screen

as though it were the monitor the design was displaying to, and the

[second](bench/cpp/vgasource.cpp) takes a piece of your screen and creates

either [a VGA source signal](bench/cpp/vgasource.cpp) or [an HDMI source

signal](bench/cpp/hdmisource.cpp) with it.



All [video modes](bench/cpp/videomode.h)

are supported by simply creating the [simulator object](bench/cpp/vgasim.cpp)

with the appropriate mode lines, although the [memory initialization

file](bench/cpp/slide.hex) for the [outgoing demo](bench/rtl/demo.v) is

specifically formatted for a 1280x1024 screen.

The [simulator](bench/cpp/vgasim.cpp) will then create a window of that size

on any GTK enabled screen (i.e. Linux), displaying whatever image [your

design](rtl/wbvgaframe.v) is producing.



The repository also contains a [test pattern generator](rtl/vgatestsrc.v)

modeled roughly after a standard VGA pattern, although not quite the same.  As

mentioned above, there's also a frame buffered approach to drawing on the window

centered around a [wishbone enabled memory driver](rtl/imgfifo.v).  This

second capability will draw a more arbitrary image on the display.



References to VGA within this module could just as easily refer to any display.

Be careful that you match the proper polarity of the sync pulses.



## Building



There is a [master Makefile](Makefile) in this directory.  Hence, to build

this project you should be able to just clone it,

`git clone https://github.com/ZipCPU/vgasim`, run `make` in the main

directory, and then run one of the test programs, such as `main_tb`, from

within the `bench/cpp` directory.  For those that display images from the

frame buffer, such as `main_tb` or `axi_tb`, be sure to wait long enough

to see the outgoing image from the frame buffer--it takes a few seconds.



The project depends upon having both Verilator and gtkmm-3.0 installed.



## License



All of the source code in this repository is released under the

[GPLv3](https://www.gnu.org/licenses/gpl-3.0.en.html).  If these conditions

are not sufficient for your needs, other licenses terms may be purchased.