15fps to 60fps video conversion

You are right, I messed up SRAM and SDRAM. OK, I could go up to 143MHz for sure.

I experimented a bit, just to make sure that what I want to achieve is actually possible (converting 15fps HDTV to 60fps HDTV).

So I directly connected VIPSuite's test pattern generator to the Clocked Video Output again. Avalon-ST frequency is 150MHz now (please take a look at the first attached drawing). The generator outputs uniform red background with one pixel thick black frame. And I have it on the display. Great.

Now, in order to prove my concept, I inserted a Frame Buffer between Test Pattern Generator and Clocked Video Output. Avalon-ST and all the other frequencies are 150MHz (SDRAM is overclocked slightly now); please take a look at the second attached drawing. Should be OK, I presume. But, no video on the display only a floating box on the black background letting me know that the frequency is out of range, that is the vertical refresh rate is 34.3Hz?? How comes? The underflow LED is on in the same time. I caught the moment underflow goes high after power up in signal tap (the third drawing). What I see is that there is underflow occurring as soon as the middle of the third output line, and the fourth line is already corrupt.

I guess I cannot lower Clocked Video Output rate much, as the display will not work for frame rates much less than 60fps. Will experiment a bit though