利用ISE生成MIG IP后,然后将example_design中的文件来进行综合,translate过了,map出现了一个问题?
LIT:600 - IOBUFDS symbol "u_ddr2/u_ddr2_top_0/u_mem_if_top/u_phy_top/u_phy_io/gen_dqs[0].u_iob_dqs/gen_dqs_iob_ddr2.u_iobuf_dqs" (output signal=u_ddr2/u_ddr2_top_0/u_mem_if_top/u_phy_top/u_phy_io/gen_dqs[0].u_iob_d qs/dqs_ibuf) does not have IOSTANDARD specified. Map is unable to generate a default IOSTANDARD for IOBUFDS, one has to be explicitly provided.dqs_ibuf
官方的解决方案:
Map is unable to assign default IOSTANDARDs for differential I/O because IOBUFDS symbols are expanded differently depending on the IOSTANDARD involved, and this happens upstream of the point where default IOSTANDARDs are assigned. It is necessary for the user to always assign IOSTANDARDs to IOBUFDS symbols.