cyclone 3 differential input and output definitions

According to the error message, the positive pin is B18, not A18. So the reason is that you assigned the wrong pin. You always need to assign the DIFFIO_xxp pin of a differential pair.

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Hi,

I will assign my signal to DIFFIO_xxp if I design from scratch. But in this

case I have to use DIFFIO_xxn to assign my signal port MYSIG. Quartus II automatically create MYSIG(n) on pin DIFFIO_xxp. If so, why the tool also

complain with Error??? It is a little strange.

Is there a option in Quartus to allow me to assign differential signal with inversion: positive port to negative pin, negative port (autogenerated by Quartus) to positive pin?

Thanks a lot !