标签：HUD IOSTANDARD TERM 50 约束 UCF dram NET mcb3
1、注释使用#或//，而非verilog中的/* */
2、周期时钟约束
NET "sysclkin_50M" TNM_NET = "CLK_IN1";
TIMESPEC "TS_CLK_IN1" = PERIOD "CLK_IN1" 50.0 ns HIGH 50%;
NET "sysclkin_50M" CLOCK_DEDICATED_ROUTE = FALSE;
NET "sysclkin_50M" IOSTANDARD = LVCMOS33 ;
NET "sysclkin_50M" LOC = "AB13" ;//"Y13" ;
第一条约束定义时钟sysclkin_50M驱动的所有同步器件为一个分组，即CLK_IN1；
第二条约束定义CLK_IN1时钟组其周期为50ns，即20MHZ,占空比为50%，波形产生第一个点评为高电平。
第三条特殊时钟约束：CLOCK_DEDICATED_ROUTE，当时钟从普通IO输入非时钟网络引脚输入时，FPGA会产生报警，若想要忽略并继续工作定义该条约束即可
第四条约束定义管脚电器类型为LVCMOS33
第五条约束定义管脚位置，即将sysclkin_50M约束到管脚AB13上
3、约束辅助电压VCCAUX电压值
CONFIG VCCAUX=3.3;
4、ddr约束
NET "mcb3_dram_dq[*]" IN_TERM = NONE;
NET "mcb3_dram_dqs" IN_TERM = NONE;
NET "mcb3_dram_dqs_n" IN_TERM = NONE;
NET "mcb3_dram_udqs" IN_TERM = NONE;
NET "mcb3_dram_udqs_n" IN_TERM = NONE;
以上几条是用来约束内部阻抗的，此处内部阻抗为无
NET "mcb3_dram_dq[*]" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_a[*]" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_ba[*]" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_dqs" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_udqs" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_dqs_n" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_udqs_n" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_ck" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_ck_n" IOSTANDARD = DIFF_SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_cke" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_ras_n" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_cas_n" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_we_n" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_odt" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_dm" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_dram_udm" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_rzq" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
NET "mcb3_zio" IOSTANDARD = SSTL18_II |OUT_TERM = UNTUNED_50;
以上几条用来对信号进行约束，IOSTANDARD 约束电气标准，
OUT_TERM约束为非ip core建议匹配，约束外部阻抗，强制要求匹配阻抗为50Ω
标签：HUD,IOSTANDARD,TERM,50,约束,UCF,dram,NET,mcb3 来源： https://www.cnblogs.com/gaoyong-512/p/10613806.html
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