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Altera_Forum
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14 years ago

Frame Buffer IP stops output during first frame. No EOP

Hi! I haven't found any posts describing my problem, which is : I have a Frame Buffer IP. In QSYS, it's configured to support maximum 1280x720 pixels. I actually transmit 640x480 pixels f...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
14 years ago

Some more observations. Possibly the solution:

I tried forcing the read_master_av_readdatavalid signal to '1', emulating that the RAM feeds more data to the Frame Buffer reader process. (Although it doesn't request any more data). With this readvalid kept high, the frame buffer outputs 67 more pixels, and then finally asserts EndOfPacket!

I examined the read_master interface some more, and found that at the beginning of the frame, the second burst request towards the RAM appears before the first read burst is done. I guess that the Frame buffer is expecting the RAM to deliver this data, but my home-made RAM model doesn't buffer multiple read burst requests. I guess the interface requires it, although it seems like a strange feature in a protocol...?

The attachement shows the two burst requests towards my RAM model. These requests are generated by Frame Buffer IP and some glue logic in .vho files made by QSYS.