计数器在数字电路中的应用

Applications of counter in digital circuits

计数器是典型的时序逻辑电路,也是数字系统中使用最多的时序逻辑器件。为了更好地理解和扩展集成计数器件的性能和用途,达到举一反三、灵活运用的目的。以中规模集成计数器74LS192为例,选用两片74LS192构成预置数的三十进制递减计数器,计数器十位接成三进制,计数器个位接成十进制,完成30s递减计时;另外,选用一片74LS192和一片输出低电平有效的3-8线译码器CT74LS138构成顺序脉冲发生器。通过以上实例的方法,得到了计数器不但具有传统的计数定时功能之外,还可用作顺序脉冲发生器的结论。

The counter is a typical sequential logic circuits, and a sequential logic device mostly used in digital systems. In order to better understand and expand the performance of integrated devices, draw inferences about other cases from one in- stance, and realize the purpose of flexible application, taking an integrated counter 74LS192 as an example, two 74LS192 counters were selected to form a three-decimal down counter with preset number. The counter accesses decade into the ternary connected as a decimal, to complete 30 s decreasing timing. In addition, a 74LS192 and a decoder CT74LS138 were selected to constitute a sequential pulse generator. By the method of the above instances, the counter has the function of traditional counting timer, and can also be used as a pulse generator.