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目 录 引言 paper51.com
一、系统简介············································································································ 1 http://www.paper51.com 1.1明确待设计系统的功能要求············································································ 1 paper51.com
1.2要实现系统的逻辑功能··················································································· 1 内容来自论文无忧网 www.paper51.com 1.3拟定数字系统的总体方案················································································ 1 copyright paper51.com 二、芯片的功能介绍································································································· 1 paper51.com 2.1 74LS161芯片的功能······················································································· 1 内容来自论文无忧网 www.paper51.com
2.274LS192芯片的功能······················································································· 3 copyright paper51.com 2.3 系统其它部件介绍························································································· 4 内容来自论文无忧网 www.paper51.com
内容来自www.paper51.com 三、系统的实现原理································································································· 5 http://www.paper51.com 3.1器件的选用····································································································· 5 copyright paper51.com 3.2系统工作原理································································································· 6 http://www.paper51.com 四、数字电路设计过程中的注意事项········································································· 6 内容来自论文无忧网 www.paper51.com 4.1导线和芯片的检测·························································································· 6 copyright paper51.com
4.2实验线路连接过程及注意事项········································································· 6 copyright paper51.com
4.3功能调试及实现····························································································· 6 copyright paper51.com 4.4焊接过程及注意事项······················································································ 6 copyright paper51.com 参考文献 内容来自www.paper51.com 致谢 http://www.paper51.com
引言 内容来自论文无忧网 www.paper51.com 篮球比赛是根据运动队在规定的比赛时间里得分多少来决定胜负的, 因此, 篮球比赛计分就显得十分重要，并且在比赛过程中需及时向观众显示各种比赛信息，以便观众对所进行的比赛有一个清楚的了解。早期一般使用灯泡制作显示屏来显示信息，但灯泡寿命短，用其制作的显示屏可靠性差。近年来LED显示有了重大发展，发光二极管具有寿命长、工作电压低等特点，用其制作很受人们的青睐，且便于随带,为在室外举行比赛提供极大地方便，能方便地实施计时暂停,保证了计时的准确性和灵活性，可以较好地用于篮球、排球、乒乓球等球类比赛时计分,具有广泛的适用范围。 copyright paper51.com 一、系统简介 内容来自www.paper51.com 1.1明确待设计系统的功能要求 paper51.com
根据篮球比赛的实际情况，有得1分、2分和3分的情况，还有减分的情况，电路要具有加、减分及显示功能。 内容来自论文无忧网 www.paper51.com 用2片四位二进制加法计数器74LS161分别组成二进制、三进制计数器，控制加2分、3分的计数脉冲。3片十进制可逆计数器74LS192组成的加、减分计数器用于总分累加，最多可计999分，显示译码器用于显示得分。 内容来自www.paper51.com
开始计分时，按一下复位钮S，使计数器74LS192和74LS161全部清零。以2分球为例：当进一个2分球时，按一下2分按钮，使LD=0，计数器74LS161(2)预置1110，Q3Q2Q1Q0通过或门输出1，使与门2分打开，让另分计数脉冲通过，同时使74LS161(2)的T端为1，并且经过非门2输出0，使LD=1,这时74LS161（2）开始计数，计2个脉冲后，Q3Q2Q1Q0状态为0000，使或门输出为0，封锁与门2，阻止第3个以后的加分脉冲通过 ，同时使74LS161的T端为0，使计数器保持状态不变，并通过非门2输出1，使与非门2打开，完成了计2分过程，等待下一次2分按钮按下。计3分同理，计1分更为简单。 copyright paper51.com
1.2要实现系统的逻辑功能 copyright paper51.com “篮球计分显示器”应实现三点基本逻辑功能：第一：清零功能，由计分员控制，当一场比赛开始时，清除显示器上的所有信号；第二：计数功能，应能实现加1、2、3分或减1、2、3分的功能；第三：保持功能，当加分完成后，计数器保持状态不变。 http://www.paper51.com
1.3 拟定数字系统的总体方案 内容来自论文无忧网 www.paper51.com 1、清零功能：在常见的触发器中，RS触发器的主要功能是置位(置“1”)与复位(置“0”或清"0" ), T触发器和JK触发器都带有清除端CLR，它们的功能比较灵活，可实现RS触发器的功能，也可以相互转换，因此选用T触发器或JK触发器都可以满足此功能。 内容来自论文无忧网 www.paper51.com
2、加分功能：通过74LS161连接到74LS192的CP+上，实现加法功能。 copyright paper51.com 3、减分功能：通过74LS161连接到74LS192的CP-上，实现减法功能。 内容来自论文无忧网 www.paper51.com 4、显示功能：通过三片74LS192的输出连接到数码显示器上，使之能从000---999分或999---000分。 copyright paper51.com
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