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目录摘要···········································································21计算器总体方案论证·······················································
31.1计算器的设计任务和要求················································
31.2实现加减计算器的基本方法·············································32硬件电路设计·······························································
42.1系统结构图································································
42.2芯片分析··································································
42.3外部接线图································································53结果模拟与分析····························································
73.1加法电路的实现··························································
73.2减法电路的实现·························································7总结···········································································9参考文献·····································································101计算器总体方案论证·······················································
31.1计算器的设计任务和要求················································
31.2实现加减计算器的基本方法·············································32硬件电路设计·······························································
42.1系统结构图································································
42.2芯片分析··································································
42.3外部接线图································································53结果模拟与分析····························································
73.1加法电路的实现··························································
73.2减法电路的实现·························································7总结···········································································9参考文献·····································································10摘要加减法计算器,就是能够通过开关控制进行加法运算和减法运算,并利用数码管显示计算结果通过对计数器功能的认真研究和上网查了诸多方面的资料本简易加减法计数器主要由3个主要版块组成编码输入电路、加减运算电路和显示电路输入电路通过开关的闭合和开通来代表电平的高地位继而代表0和1来输入所要计算的十进制数字加减运算电路加减运算电路主要由74LS283(双全加器)的级联电路组成通过非门将原码全部转换为反码,再把74LS283输入进位置为1,然后采用个位和个位相加,十位和十位的相加的原则,将两个的个位的代码送入到一个加法器中,将进位依次传递但是加法器只可以做加法运算,不满足我们的设计要求,于是我们将减法也变成加法进行运算,运算都用补码,最后再将结果在转换为原码,通过数码管灯显示出来显示电路显示电路时通过7段显示译码器来实现的本课题通过PROTEUS仿真达到了课题的各项要求,证明了本课题真实、可靠关键词74LS238;74LS47;数码管;计算器1计算器总体方案论证
1.1计算器的设计任务和要求任务完成一个简易加减计算器的设计要求:
(1)用于两位以下十进制数的加减运算
(2)以合适方式显示输入数据及计算结果
1.2实现加减计算器的基本方法该方案由三个模块组成编码输入电路、加减运算电路和显示电路通过开关J1——J8接不同的高低电平来控制输入端所置的两个一位十进制数,译码显示器U10和U13分别显示所置入的两个数数A直接置入四位超前进位加法器74LS283的A4——A1端,74LS283的B4——B1端接四个2输入异或门四个2输入异或门的一输入端同时接到开关S1上,另一输入端分别接开关J5——J8,通过开关J5——J8控制数B的输入当开关S1接低电平时,B与0异或的结果为B,通过加法器74LS283完成两个数A和B的相加当开关J1接高电平时,B与1异或的结果为B非,置入的数B在74LS283的输入端为B的反码,且74LS283的进位信号C0为1,其完成S=A+B(反码)+1,实际上其计算的结果为S=A-B完成减法运算由于译码显示器只能显示0——9,所以当A+B9时不能显示,我们在此用另一片芯片74LS283完成二进制码与8421BCD码的转换,即S9
(0110)2时加上6
(0110)2,产生的进位信号送入译码器U15来显示结果的十位,U14显示结果的个位由于减法运算时两个一位十进制数相减不会大于10,所以不会出现上述情况,用一片芯片U14即可显示结果2硬件电路设计
2.1系统结构图系统的结构图如图
2.1所示图
2.1系统结构图
2.2芯片分析全加器74LS283的逻辑图如图
2.2所示图
2.274LS283引脚图二进制计算中,主要采用74ls283来实现功能,其中的异或门来控制加减计算,当异或门控制信号等于0时,电路执行加运算,当异或门控制信号为1时,电路执行减运算全加器74LS283的逻辑功能是将输入端口A1~A
4、B1~B4的输入数据作为二进制的数码进行相加,并把运算的结果在输出端口S1~S4输出C4是来至低位的进位,而CO是高位进位的输出BCD七段译码器74LS47简介如图
2.3所示图
2.374LS47引脚图BCD七段译码器74LS47的逻辑功能是将输入端ABCD的输入在七段反码A~G上显示若ABCD=0,则输出显示为
02.3外部接线图该电路运用了BCD七段译码器74LS47芯片和全加器74LS283芯片,同时,电路图中也大量的使用与门、非门、与非门和异或门在这些元器件的重复使用过程中也就自然的达到了课程设计所要求的结果后经仿真证实了该电路设计的合理性与正确性系统外部接线图如图
2.4图
2.4系统外部接线图3结果模拟与分析
3.1加法电路的实现用两片4位全加器74LS183和门电路设计一位8421BCD码加法器由于一位8421BCD数A加一位数B有0到18这十九种结果而且由于显示的关系当大于9的时候要加六转换才能正常显示如模拟电路图
3.1该加法电路实现的功能是24+79=103图
3.1加法电路
3.2减法电路的实现该电路功能为计算A-B若n位二进制原码为N原,则与它相对应的补码为N补=2n-N原,补码与反码的关系式为N补=N反+1,A-B=A+B补-2n=A+B反+1-2n因为B1=B非,B0=B,所以通过异或门74LS86对输入的数B求其反码,并将进位输入端接逻辑1以实现加1,由此求得B的补码加法器相加的结果为A+B反+1,如模拟电路图
3.2该减法电路实现的是79-24=55图
3.2减法实现电路总结从本次课程设计的过程中,我发现自己学到了很多东西,实现加强了已经学到的关于电路、数电的知识在课程设计的过程中更重要的是我明白了合作对于一个团体的重要意义经过两个礼拜的努力,终于幸不辱命,把这个简易加减计算器做了出来,功能也基本上满足了课程任务书的要求另外在本次课程设计中发现自己的很多不足,最明显的感触就是,课堂上学的东西要与实践联系起来还是有一段距离,但自己也学到了很多东西,严谨的科学态度对于一个搞工程的人来说是很重要的,一件优秀的工业设计不仅考验一个设计师的才干和智慧,同时也更加决定一个企业的生存和市场竞争在以后的学习中我们要理论联系实际,自己能动手的多动手去做,古人的智慧“纸上得来终觉浅,绝知此事要躬行”是没有错的还有在以后的学习中,我们面对困难要迎难而上,相信只要努力去做,就一定能成功参考文献
[1]张克农、宁改娣等.数字电子技术基础(第二版)[M].高等教育出版社.
[2]胡宴如、耿苏燕等.模拟电子技术基础(第二版)[M].高等教育出版社.
[3]陈大钦.电子技术基础实验(第二版)[M].高等教育出版社.
[4]康华光.数字电子技术基础[M].清华电子学教研室高教出版社.。