说明：  注意：只有C代码。串行驱动led显示，一个74hc595位移寄存器驱动三极管驱动led位，两个74hc595驱动led段，方式位5位x8段x2=10个数码管5分频，每次扫描时间位1.25ms
(Note: Only C code. Serial driver led display, a shift register 74hc595 drive transistor drive led, and led two drives 74hc595 paragraph, ways x8 paragraph 5-bit x2 = 10个5 sub-frequency digital tube, scan time for each bit 1.25MS)