1、 电子秒表电子秒表 摘摘 要要 电子秒表是一种用数字电路技术实现时、分、秒计时的装置，无机械装置，具有较长 的使用寿命，因此得到了广泛的使用。它从原理上讲是一种典型的数字电路，其中包括了组 合逻辑电路和时序电路。本次实验所做电子式秒表由信号发生系统和计时系统构成,并具有 清零,暂停功能。由于需要比较稳定的信号，所以信号发生系统 555 定时器与电阻和电容组 成的多谐振荡器构成，信号频率为 100HZ。计时系统由计数器、译码器、显示器组成。计数 器由 74 LS160 构成，由十进制计数器组成了一百进制和六十进制计数器，采用异步进位方 式。译码器由 74LS48 构成，显示器由数码管构成。清零,
2、暂停功能由 RS 触发器构成防抖动 开关。具体过程为：由晶体震荡器产生 100HZ 脉冲信号先进入计数器，然后传入译码器，将 4 位信号转化为数码管可显示的 7 位信号，结果以“分”、“秒”、“10 毫秒”依次在数码 管显示出来。该秒表最大计时值为 59 分 59.99 秒， “10 毫秒”为一百进制计数器组成， “分”和“秒”为六十进制计数器组成。 关键词关键词：计时 精度 计数器 显示器 Abstract Electronic stopwatch is the realization of a digital circuit technology,.It can realize the h
3、our, minute, second timer.It does not have mechanical means and has a longer life, so it has been widely used. The principle is a typical digital circuit, which includes a combination logic circuit and a timing circuit. The experiments can be done by electronic stopwatch constituted by the signal sy
4、stem and timing system, and has cleared pause function. Due to the need of a more stable signal, the signal generating system is constituted by the 555 Timer with the resistors and capacitors, and the signal frequency is 100Hz. Timing system contains the counter, decoder, display. Counter 74 LS160 c
5、onstituted by the decimal counter the decimal and sexagesimal counter, which uses asynchronous binary. The decoder from 74LS48 constitute display digital tube constitute Cleared, the pause function by the RS flip-flop. Its specific process: the 100Hz pulse signal generated by the crystal oscillator
6、and first into the counter, and then the incoming decoder, a 4-bit signal is converted to 7-bit signal of the digital control can be displayed, the result by “minute“, “second“, “10 milliseconds“ turn on the digital display. The stopwatch timing is 59 minutes, 59.99 seconds, 10 milliseconds is the 150 binary counter, “minute“ and “second“ is the six decimal counter. Keyword:Timing accuracy counter display 目目 录录 一 设计任务与要求 错误错误!未定义书签。未定义书签。 二 方案设计与论证 1 三 单元电路设计与参数计算 . 6 （1）信
