Skip to content

Louadria/VideoBus

Repository files navigation

VideoBus

Verification Components for VideoBus interface. VideoBus is a simple protocol to stream video using fval (frame valid) / lval (line valid) / dval (data valid). It is commonly used to connect rather simple video blocks in a pipe. The signals are derived from the CameraLink standard, which is rather common in industrial cameras. (See: https://www.imagelabs.com/wp-content/uploads/2010/10/CameraLink5.pdf Chapter 2)

Although it is related to VSync, HSync, DataEnable video, there are no real video timings involved. I.e., there is no front porch, back porch, blanking video.

The library onsists of VideoBusRx for receiving, VideoBusTx for transmitting, and a bitmap logger for visual inspection. An example testbench is included to show how one might use these VCs, using a simple passthrough DUT. Furthermore, the library has a configurable number of data streams, in case multiple pixels are sent per cycle.

Below is an example of how a 4x4 image may be transmitted over a single data stream. timing diagram of clk/fval/lval/dval/data

When using multiple data streams, multiple sequential pixels are sent simultaneously. Below is an example of how the same 4x4 image may be transmitted over 2 data streams. timing diagram of clk/fval/lval/dval/data1/data2

Notice that the timing regarding the fval/lval/dval signals is not strict. For example, this would still be a valid transmission of the same 4x4 image: timing diagram of clk/fval/lval/dval/data1/data2 with non-strict timing

To this regard, the VideoBusTx VC has 3 model options which can be configured:

  1. FVAL_GUARD_CYCLES: number of cycles between successive frames
  2. LVAL_GUARD_CYCLES: number of cycles between successive lines
  3. DVAL_GUARD_CYCLES: number of cycles between lval high -> dval high / dval low -> lval low

These are all set to 1 by default, resulting in the timing as shown in the first 2 Figures.

Compile OSVVM and run the tests


If you are using Aldec’s Rivera-PRO or Siemen’s QuestaSim/ModelSim do the following.

  • Step 1: Create a directory named sim that is in the same directory that contains the OsvvmLibraries directory.
  • Step 2: Start your simulator and go to the sim directory.
  • Step 3: Do the following in your simulator command line:
source ../OsvvmLibraries/Scripts/StartUp.tcl
build  ../OsvvmLibraries
build  ../OsvvmLibraries/VideoBus/RunAllTests.pro

The last command will automatically recompile the ./src directory, and then run all the tests in ./testbench. The received frames will be logged as .bmp images in sim/bmp_logs/bmp_frame_X.

About

No description, website, or topics provided.

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published