--- Quote Start ---
Indeed there is, the 3th bit of the status Register (VCO) is constantly giving a five as output, which means the buffer is underflowing (I think).
--- Quote End ---
One thing to note is that the underflow bit of the status register is sticky. Once fired it will stay high until you clear it by writing a 1 to that bit. So to check for underflow you should poll the register every so often, clearing it after you've read it.
--- Quote Start ---
they also use the frame buffer between the alpha blender and the VCO. May be this is necessairy to output a nice stream of data. (just a thought)
--- Quote End ---
A Frame Buffer won't help in this case as the Frame Reader is effectively the read half of a Frame Buffer (it has the same functionality and is able to repeat output frames).
If the output is underflowing then the likely issue is that the Frame Reader isn't getting enough bandwidth from the memory interface. This could be because some other component is accessing the memory inefficiently e.g. a NIOS doing single random access reads and writes. Try running the NIOS from on-chip RAM or SSRAM to eliminate this cause.
Also the clock crossing bridge isn't necessary for the Frame Reader and may not be working efficiently. Remove it and change the clock on the Frame Reader's Avalon Master interface to be the ddr_sdram clock.
--- Quote Start ---
All the components in the SOPC use a 3 pixel in parallel transmission (which is not good for the NEEK VGA and LCD) and after the VCO he added some verliog code to serialize those three pixel data blocks for transmission to the MAX II on the LCD board.
--- Quote End ---
You could also use the Color Plane Sequencer VIP core to do this. It allows you to convert between colors in parallel and colors in sequence.
Gareth.
Honored Contributor
