Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

Avalon ST Interface Help Pleaseee

Hello All, How are you?

Finally after great help from Jake and thiago on this forum , I have been able to chalk out my video out interface. But now I am having problems in interfacing my custom made Avalon ST block to the Video IP.

I use a SGDMA to send data out to the Avalon ST block which then applies colorization to the pixels coming in and spits them back out to the video IP.

I have checked everything, and still not been able to figur out what the problem is.

Firstly I Set the Colorization Block to always Convert pixels to one color, just to see if the whole process works and that i can see the color on the screen. But weirdly enough although all signals seem correct in signal Tap I am Getting 3 different colored stripes, and the image shakes from right to left.

I have checked with counters to make sure that the right amount of data is being spit out, and also checked that the f1 and f2 control packets are sent out before every video packet. I have also check to see if the start of packet and of packets synchronized.

And everything seems right, Please can some one suggest what the problem could be.

regards,

nadeem jamal

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    So would you say you are experiencing a single-pixel shift on every frame? Are the 3 colored stripes vertical or horizontal (I assume vertical). How wide are the three different color stripes? What colors are they? What color are you trying to display?

    Are you appropriately handling the ready latency of the Avalon ST interface? The video IP assumes a ready latency of 1. Meaning the valid data is expected to be presented on the clock cycle following the assertion of the ready signal.

    Jake
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    18 years ago

    Hello Jake , Thanks again for your quick response.

    Yes the three stripes are Vertical , The RGB Values I am sending are 255,128,64 and the colors are Dark Green, Dark Redish and Dark Blueish.

    Yes I have made sure that the block is rd latency of one but yet cant figure out where the problem is.

    I also checked if the sop and EOP come at the write symbols. Also checked the whether the symbols are right.

    You must be right it is shifting a pixel a frame..

    But how do i figure out where ? is there any good way of checking if my avalon st block is working correctly?

    I am just trying the Test checker block , but not to sure how it will know what data I am sending it and that whether it is right and how many symbols it should expect.

    thnking you nadeem jamal