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Altera_Forum
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15 years ago

Source of errors in data from SGDMA

Hello, Sorry to be back so quick but I have spent the last two days on this and am at a loss. I have an SGDMA which is reading 16 bit data from an 8bit SDRAM and streaming this to a vide...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Hello,

I have played with the timing settings of the SDRAM controller without much success.

Modifying the t_ac access time and the t_wr (data write recovery time) resulted in a greater range of erroneous values but no signifcant change in reliability.

I put SignalTap on the SDRAM data and control lines and my scope on a couple to have a look at what it was doing. (At this point I was writing a value of 185, below 255 so I could try and see why the bytes were shifting position)

The only thing that stands out to me is the waveform of the line Data0 on the scope in comparison to the clock, and that is that its rise time is equal to an entire wavelength of the clock, could this be the source of the errors?