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,*,*,1,组合规律电路,第,4,章,Combinatorial Logic Circuits,A multiplexer(MUX)is a device that allows digital information from several sources to be routed onto a single line for transmission over that line to a common destination.,The basic multiplexer has several data-input lines and a single output line.It also has data-select inputs,which permit digital data on any one of the inputs to be switched to the output line.Multiplexers are also known as data selectors.,2,发光二极管,LED,(Light Emitting Diode),材料；砷化镓，磷化镓，磷砷化镓,单个,LED,的工作电流,520mA,，工作电压,1.53V,。,响应时间,100nS,。,R,+5V,LED,七段字符显示器,LED,点阵显示器,3,七段字符显示器,共阴极,共阳极,a=1,b=1,d=1,e=1,g=1,c=0,f=0,4,4.3.4,显示译码器,LED,七段字符显示器和液晶显示器都可以用,TTL,或,CMOS,集成电路直接驱动。需要用显示,译,码器把要显示的字符的,BCD,码,译成,七段字符显示器所需要的驱动信号。,BCD,码,七段码,显示译码器,七段字符,显示器,BCD,码,七段码,附加掌握信号,5,BCD七段字符显示译码器 代码转换器7448,1,1,1,1,0,0,0,0,1,1,1,14,0,0,0,0,0,0,0,1,1,1,1,15,1,1,0,1,0,0,1,1,0,1,1,13,1,1,0,0,0,1,0,0,0,1,1,12,1,0,0,1,1,0,0,1,1,0,1,11,1,0,1,1,0,0,0,0,1,0,1,10,1,1,0,0,1,1,1,1,0,0,1,9,1,1,1,1,1,1,1,0,0,0,1,8,0,0,0,0,1,1,1,1,1,1,0,7,1,1,1,1,1,0,0,0,1,1,0,6,1,1,0,1,1,0,1,1,0,1,0,5,1,1,0,0,1,1,0,0,0,1,0,4,1,0,0,1,1,1,1,1,1,0,0,3,1,0,1,1,0,1,1,0,1,0,0,2,0,0,0,0,1,1,0,1,0,0,0,1,0,1,1,1,1,1,1,0,0,0,0,0,字形,Y,g,Y,f,Y,e,Y,d,Y,c,Y,b,Y,a,A,0,A,1,A,2,A,3,数字,输 出,输 入,6,2.BCD七段字符显示译码器代码转换器7448,1,1,1,1,0,0,0,0,1,1,1,14,0,0,0,0,0,0,0,1,1,1,1,15,1,1,0,1,0,0,1,1,0,1,1,13,1,1,0,0,0,1,0,0,0,1,1,12,1,0,0,1,1,0,0,1,1,0,1,11,1,0,1,1,0,0,0,0,1,0,1,10,1,1,0,0,1,1,1,1,0,0,1,9,1,1,1,1,1,1,1,0,0,0,1,8,0,0,0,0,1,1,1,1,1,1,0,7,1,1,1,1,1,0,0,0,1,1,0,6,1,1,0,1,1,0,1,1,0,1,0,5,1,1,0,0,1,1,0,0,0,1,0,4,1,0,0,1,1,1,1,1,1,0,0,3,1,0,1,1,0,1,1,0,1,0,0,2,0,0,0,0,1,1,0,1,0,0,0,1,0,1,1,1,1,1,1,0,0,0,0,0,字形,Y,g,Y,f,Y,e,Y,d,Y,c,Y,b,Y,a,A,0,A,1,A,2,A,3,数字,输 出,输 入,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,1,1,1,1,0,0,1,1,1,0,0,0,0,11,10,Y,a,的卡诺图,Y,b,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,1,1,0,1,1,1,0,1,0,1,1,0,0,0,0,11,10,Y,c,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,1,1,1,1,0,1,1,0,0,1,1,0,0,1,0,11,10,Y,d,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,1,1,1,0,1,0,1,1,0,0,1,1,1,11,10,Y,e,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,0,0,1,0,1,0,0,1,0,0,1,0,1,11,10,Y,f,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,1,1,0,0,0,1,1,1,1,1,0,1,0,0,11,10,Y,g,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,0,0,1,1,1,1,0,1,1,1,1,1,0,1,1,1,11,10,7,Y,a,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,1,1,1,1,0,0,1,1,1,0,0,0,0,11,10,Y,b,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,1,1,0,1,1,1,0,1,0,1,1,0,0,0,0,11,10,8,Y,c,的卡诺图,Y,d,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,1,1,1,1,0,1,1,0,0,1,1,0,0,1,0,11,10,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,1,1,1,0,1,0,1,1,0,0,1,1,1,11,10,9,Y,e,的卡诺图,Y,f,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,0,0,0,1,0,1,0,0,1,0,0,1,0,1,11,10,A,3,A,2,A,1,A,0,00 01,00,01,11 10,1,0,1,1,0,0,0,1,1,1,1,1,0,1,0,0,11,10,10,Y,g,的卡诺图,A,3,A,2,A,1,A,0,00 01,00,01,11 10,0,0,1,1,1,1,0,1,1,1,1,1,0,1,1,1,11,10,用,7448,驱动七段字符显示器的连接方法,11,7448的附加掌握信号：,灯测试输入,当 时，,Ya Yg,全部置为,1,灭零输入,当 ，时，,则灭灯,灭灯输入,/,灭零输出,1.,输入信号，称灭灯输入控制端：,无论输入状态是什么，数码管熄灭,2.,输出信号，称灭零输出端：,只有当输入 ，且灭零输入信号 时，,才给出低电平,因此 表示译码器,将本来应该显示的零熄灭了,12,例：利用 和 的配合，实现多位显示系统的灭零控制,整数部分：最高位的,0,，而且灭掉以后，输出 作为次高位的 输入信号,小数部分：最低位的,0,，而且灭掉以后，输出 作为次低位的 输入信号,灭零输入,灭灯输入,/,灭零输出,1,13,4.4.1,数据选择器,Multiplexer,4,选,1,数据选择器,MUX,0 0,MUX,0 1,MUX,1 0,MUX,1 1,数据输入,数据输出,地址,输入,4.4,数据选择器,14,4.4.1,数据选择器,Multiplexer,4,选,1,数据选择器,MUX,简化真值表,A,1,A,0,D,0,D,1,D,2,D,3,F,0,0,0,0,0,1,1,0,0,1,0,1,1,0,地址,输入,使能端,数据输入,15,集成,“双四选一”,数据选择器,，,74HC153,例：,A,1,A,0,D,10,D,11,D,12,D,13,Y,1,0,0,0,0,0,1,1,0,0,1,0,1,1,0,A,1,A,0,D,20,D,21,D,22,D,23,Y,2,0,0,0,0,0,1,1,0,0,1,0,1,1,0,地址,16,用两个“四选一”接成“八选一”,“,四选一”只有,2,位地址输入，从四个输入中选中一个,“,八选一”的八个数据需要,3,位地址代码指定其中任何一个,八选一数据选择器的规律函数：,17,用两个“四选一”接成“八选一”,1,1,A,2,=0,，,A,2,=1,，,地址,数,据,数,据,18,4.4.2 用数据选择器设计组合规律电路,1.根本原理,具有n位地址输入的数据选择器，可产生任何形式的输入变量不大于n+1的组合规律函数。,规律函数不化简，而要变换成与数据选择器的规律函数一样的形式。,19,例：用数据选择器设计一个监视交通信号灯状态的规律电路,规律函数不化简，而要变换成与数据选择器的规律函数一样的形式,20,用集成,“双四选一”,数据选择器,74HC153,
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