I'm using the Altera SD Card IP Core with Nios II, and I have a few questions regarding the timing constraints. The Doc says : --- Quote Start --- Finally, it is important to set Tco and Tsu constraints for the SD card ports. Both parameters should be set to not more than 10ns. Should the parameters be omitted during design compilation, it is possible that the core may malfunction. --- Quote End --- But should I affect constraints to the 4 sd card output ports (including the clk one)? And what will be my reference clock for that, the clk input pin (50Mhz) or as I have seen on some thread, the sd card clock output port? Thanks a lot for the help!