fpga 串行口 接收和发送程序，采用verilong语言编写-fpga uart ，receive and send include writed by verilog language

采用Verilong编写的等精度频率计，调试成功可测频率、周期、占空比、正负脉宽。-Written using Verilog and other precision frequency meter, debugging success can be measured frequency, period, duty cycle, positive and negative pulse widths.