本文举例说明了如何用软件实现脉宽调制(PWM)，如何将该设计转换成一个可以在FPGA中运行的逻辑块，并能利用存储器映射I/O接口通过软件完成对该逻辑块的控制。- the paper illustrates how to use software pulse width modulation (PWM), how can the design into a run in the FPGA logic blocks, and can use memory mapped I/O Interface completion of the logic block through software control.