[参]基于FPGA的DDS实现
基本参照
http://www.eetree.io/doc/stepfpgadds20k
verilog基本语法
https://blog.csdn.net/zhangshuaiisme/article/details/78993582
always块的使用
https://blog.csdn.net/kebu12345678/article/details/81332093
基于小脚丫（FPGA开发板）和旋转编码器的LED控制
https://www.cirmall.com/circuit/2704/基于小脚丫（FPGA开发板）和旋转编码器的LED控制#/details
小脚丫step FPGA旋转式编码开关
http://www.cirmall.com/bbs/forum.php?mod=viewthread&tid=45184&highlight=小脚丫?mod=viewthread&tid=45184&highlight=小脚丫