利用计数器设计延时函数，通过四个led灯的闪烁，可以直观观察延时时长，fpga器件cyclone iv LCMXO2-1200HC-4TG144CR1,在demo板上作简路图(Using the counter to design the delay function, through the flashing of four LED lights, we can observe the delay time directly, FPGA device cyclone IV LCMXO2-12