在做一个项目应用时，使用的I/O较多，应用到了74595来做扩展，但是若要挂接多片74595，势必也要多用到I/O口，为了解决这个问题，我将每2片74595做级联，然后再将级联之后的所有时钟线与数据再并联在一起（即所有的74595共用时钟与数据线，故只占用2个I/O口线），最后对每一组的锁存控制线做单独控制（在这里也相当于片选了），这样一来硬件电路得到了很大程度的简化，同时在程序上也可以共用一个74595的驱动子程序，控制不同的锁存控制线，串行数据也就送到了不同74595级联模组端口。故此对硬件与软件都有很大程度的优化。-Application to do a project, the more I/O, applied to the 74,595 to do the extension, but you want to mount multi-chip 74595, is bound to have a lot to use the I/O port, in order to solve this problem, I will be every 2 sheet 74595 do cascade, and then cascade after all the clock line and the data in parallel and then together (i.e., all 74595 communal clock and data lines, it only occupies two I/O port lines) Finally, for each group latch control lines do individually controlled (equivalent to Chip Select), so that a hardware circuit by a great degree of simplification, both procedures can also share a driving subroutine 74595, to control the type of lock inventory control line, serial data is sent to the port 74595 cascade module. As a result of the hardware and software have a large degree of optimization.