一、 设计任务
1. 抢答器同时供 8 名选手或 8 个代表队比赛，分别用 8 个按钮 S0 ~ S7 表示。
2. 设置一个系统清除和抢答控制开关 S，该开关由主持人控制。
3. 抢答器具有锁存与显示功能。即选手按动按钮，锁存相应的编号，并在 LED 数码管上显示，同时扬声器发出报警声响提示。选手抢答实行优先锁存，优先抢答选手的编号一直保持到主持人将系统清除为止。
4. 抢答器具有定时抢答功能，且一次抢答的时间由主持人设定（如 30 秒）。当主持人启动"开始"键后，定时器进行减计时，同时扬声器发出短暂的声响，声响持续的时间 0.5 秒左右。
5. 参赛选手在设定的时间内进行抢答，抢答有效，定时器停止工作，显示器上显示选手的编号和抢答的时间，并保持到主持人将系统清除为止。
6. 如果定时时间已到，无人抢答，本次抢答无效，系统报警并禁止抢答，定时显示器上显示 00。
二、设计方案
1.设计分析
抢答器具有锁存、定时、显示和报警功能。即当抢答开始后，选手抢答按动按钮，锁存器锁存相应的选手编码，同时用 LED 数码管把选手的编码显示出来，并且开始抢答时间的倒计时，同时用 LED 数码管把选手的所剩抢答时间显示出来。而在选手按键抢答以及抢答时间倒计时到时的时候都有报警以提醒主持人和选手。抢答时间设定 30 秒。接通电源后，主持人将开关拨到“清除”状态，抢答器处于禁止状态，编号显示器灭灯，定时器显示设定时间；主持人将开关置“开始”状态，宣布“开始”抢答器工作。定时器倒计时。选手在定时时间内抢答时，抢答器完成：优先判断、编号锁存、编号显示、扬声器提示。当一轮抢答之后，定时器停止、禁止二次抢答、定时器显示剩余时间。如果再次抢答必须由主持人再次操作“清除”和“开始”状态开关。
目录
一、设计任务·······································································································2
二、设计方案·······································································································2
1.设计分析········································································································································2
2.系统框图········································································································································3
三、单元电路设计································································································3
1.抢答电路········································································································································3
2.定时电路········································································································································5
3.报警电路········································································································································7
4.时序控制电路································································································································8
四、八路抢答器总电路图及工作流程··································································9
1.总电路图········································································································································9
2.工作流程······································································································································10
五、总结·············································································································10
六、参考文献·····································································································11
仿真文件
电路multisim文件.zip
(2.78 MB, 售价: 2 E币)
完整文档
八路抢答器设计报告.pdf
(631.33 KB, 售价: 3 E币)
最终电路中的抢答电路由于在默认情况下显示7,原因是由于编码器在不编码的时候输出全为高导致,所以又做个改进的电路.原理一样.只是用两片8-3编码构成了16-4编码.可以跳过0号.即:选手编号变为1-8号,而不是原来的0-7号.
倒计时电路中控制到00时候停止计时,有的人用的是高位产生借位信号时候反回一信号使计时停止,但是本人没有仿真成功.所以采用了图中接法.原理很简单,但是连线较多.
关于47和48,事实48完全可以代替47,但是本人仿真的时候也没有成功.7断a和k都试过了.百度了一下,很多人也遇到了此情况.故用47.
秒脉冲 不是很稳定.在仿真的时候可用一信号发生器代替.
关于报告中的J3开关,已经被我去掉,与j2合并在一起了.可以不必理会.
所有电路仅供参考
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