一个倒数计时的模块，以秒为单位，可以根据需要修改晶振频率-A countdown of the module, in seconds, you can modify the crystal frequency needed

VHDL语言写的串口发送、接收程序，根据晶振和相应的波特率修改分频器就可以实现！-Written in VHDL serial send, receive, process, according to crystal and the corresponding baud rate divider changes can be achieved!

基于fpga的数字频率计，verilog编写，可修改闸门宽度0.1s/1s/10s，可测频率1hz~1mhz，包含整个工程，内部分频模块为了仿真方便改小了，后面注释为50mhz晶振下的分频值，可根据需要自行修改-Fpga-based digital frequency meter, verilog prepared to modify the gate width 0.1s/1s/10s, measurable frequency 1hz ~ 1mhz, contains the entire