基于FPGA的verilog语言写的按键控制步进1 的输出占空比从1 到99 的脉冲波，并用两位数码管显示出脉冲波占空比，按键key10加1 ,按键key11减1 。-FPGA-based verilog language button control stepper output duty cycle of 1 from 1 to 99 of the pulse wave, and use two digital tube display pulse duty cycle, key ke