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Altera_Forum
Honored Contributor
Honored Contributor'Pseudo-Differential I/O' Error
I'm currently designing a DDR2 controller and have gotten far enough that I'd like to implement the design and check my work. I threw it into Quartus II 9.1 and have been getting the following error concerning the pin layout.
Error: Pin "DDR2_DQS[1]" has a pseudo-differential I/O standard but does not have its complement pin. Because the output enable of the buffer is in use, the Fitter will not create a negative pin without a complement output enable path. I generate the DDR2_DQS signal, and it is my understanding that Quartus will automatically come up with its partner (which seems to have been named DDR2_DQS[1](n) ). Does anyone have any idea how to get around this problem? I've tried multiple solutions to no avail. I'm currently trying to generate both parts of the differential using a bi-direction pseudo-differential buffer megawizard, but I don't believe that will work either. Any advice would be great!2 Replies
Altera_Forumyour best best is probably to generate an Altera DDR2 core and trace the dsq and dqs_n pins back to their driver. the PHY is clear text, so you'll be able to read the RTL
- Altera_Forum
Altera's DDR3 core has explicit dqs and dqs_n pins. my guess is that the reason is mentioned in the error, "Because the output enable of the buffer is in use, the Fitter will not create a negative pin without a complement output enable path."
