Camera writing images to SDRAM, and needs to output to VGA monitor real time

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1.) How can we solve that issue / sdram contention?

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You need to add arbitration logic. If you are using Qsys/SOPC Builder, it will do this automatically for you; otherwise, write it yourself.

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2.) Um the vga , when it requests for the pixel values, the values needs to be there immediately. The problem is we are using SDRAM and in order to read a value from a given address, itt akes around a few clock cycles or latency I am afraid it will be complicated

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You need to add an appropriately sized buffer (FIFO) to both your camera writing and VGA reading components [or elsewhere in the design]. You need to efficiently write/read the SDRAM using burst transactions.

An underrun condition on the VGA (or an overrun condition on the camera) is a critical problem and you should be sure to have status bits to indicate the condition has occurred.