某些简单异步计数器的设计,可以分析编码表和波形图,定出各触发器激励端及时钟信号的连结方式,从而得出逻辑图。但对于一些复杂的问题,用这种拼凑法设计就比较困难。作者认为可采用时钟覆盖法设计,其设计方法就是借助于卡诺图(简称 K 图),选择最佳时钟信号得到最简激励函数。下面对所用五个步骤逐个加以说明:第一步:确定 N 进制计数器的级数 n,即所用触发器个数。N 与 n 之间应满足关系式 2~(n-1) Some simple asynchronous counter design, you can analyze the code table and waveform, determine the trigger end of each trigger and the clock signal connection, resulting in a logic diagram. However, for some complicated problems, it is difficult to design with this patchwork method. The authors believe that the clock coverage method can be used to design, the design method is to use the Karnaugh map (K), select the best clock signal to get the most simple incentive function. The following five steps used to illustrate one by one: The first step: to determine the number of N-ary counter n, that is, the number of triggers used. N and n should satisfy the relationship between 2 ~ (n-1)