DQ and DQS pins

[Altera_Forum]

Hello everybody, 

 I would like to know which are the functions of these pins and why are some dedicated pins inside the banks of the fpga.  In a hw design, is it necessary to attach the ssram/ddr data pins to the dq/dqs pins in the banks of the fpga?  Many thanks.

[Altera_Forum]

Hi, 

 DDR memories have to use dedicated pins for data and strobes => dq/dqs.  SRAM is more tolerant and you don't have to use these pins.  Check "external memory interface handbook" (emi.pdf) document if you want to use DDR. The last chapter is a tutorial for DDR.  You can also check altera development kit schematics (choose a kit with similar components) to understand external needs (pull up/down...).

[Altera_Forum]

Hi, 

 I think the exact answer depends on the device family you use. But the short recommendation is: Use the "predefined" pins, otherwise Quartus might give you errors when using I/Os for DDR (even when there is no real physical reason inside the FPGA that prevents the pins from using them as DDR-I/O).  Regards,  Thomas