8线-3线编码器

自我检测题1．组合逻辑电路任何时刻的输出信号，与该时刻的输入信号 有关 ，与以前的输入信号 无关 。

2．在组合逻辑电路中，当输入信号改变状态时，输出端可能出现瞬间干扰窄脉冲的现象称为 竞争冒险 。

3．8线—3线优先编码器74LS148的优先编码顺序是7I 、6I 、5I 、…、0I ，输出为2Y 1Y 0Y 。

输入输出均为低电平有效。

当输入7I 6I 5I …0I 为时，输出2Y 1Y 0Y 为 010 。

4．3线—8线译码器74HC138处于译码状态时，当输入A 2A 1A 0=001时，输出07Y ~Y = 。

5．实现将公共数据上的数字信号按要求分配到不同电路中去的电路叫 数据分配器 。

6．根据需要选择一路信号送到公共数据线上的电路叫 数据选择器 。

7．一位数值比较器，输入信号为两个要比较的一位二进制数，用A 、B 表示，输出信号为比较结果：Y (A ＞B ) 、Y (A ＝B )和Y (A ＜B )，则Y (A ＞B )的逻辑表达式为B A 。

8．能完成两个一位二进制数相加，并考虑到低位进位的器件称为 全加器 。

9．多位加法器采用超前进位的目的是简化电路结构 × 。

（√，× ） 10．组合逻辑电路中的冒险是由于 引起的。

A ．电路未达到最简 B ．电路有多个输出C ．电路中的时延D ．逻辑门类型不同11．用取样法消除两级与非门电路中可能出现的冒险，以下说法哪一种是正确并优先考虑的A ．在输出级加正取样脉冲B ．在输入级加正取样脉冲C ．在输出级加负取样脉冲D ．在输入级加负取样脉冲12．当二输入与非门输入为 变化时，输出可能有竞争冒险。

A ．01→10B ．00→10C ．10→11D ．11→0113．译码器74HC138的使能端321E E E 取值为 时，处于允许译码状态。

A ．011 B ．100 C ．101 D ．01014．数据分配器和 有着相同的基本电路结构形式。

Verilog⼋线-三线优先编码器设计（74LS148）if语句法1//8线-3线优先编码器设计（74LS148)2//3//EI | A7 A6 A5 A4 A3 A2 A1 A0 | Y2 Y1 Y0 GS EO4//0 | 0 x x x x x x x | 0 0 0 0 15//0 | 1 0 x x x x x x | 0 0 1 0 16//0 | 1 1 0 x x x x x | 0 1 0 0 17//0 | 1 1 1 0 x x x x | 0 1 1 0 18//0 | 1 1 1 1 0 x x x | 1 0 0 0 19//0 | 1 1 1 1 1 0 x x | 1 0 1 0 110//0 | 1 1 1 1 1 1 0 x | 1 1 0 0 111//0 | 1 1 1 1 1 1 1 0 | 1 1 1 0 112//0 | 1 1 1 1 1 1 1 1 | 1 1 1 1 013//1 | x x x x x x x x | 1 1 1 1 1141516module encoder_83 (din, EI, GS, EO, dout);17input [7:0] din; //编码输⼊端data_in，低电平有效18input EI; //使能输⼊端EI（选通输⼊端），EI为 0 时芯⽚⼯作,即允许编码19output [2:0] dout; //编码输出端data_out20output GS; //⽚优先编码输出端，优先编码器⼯作⼯作状态标志GS，低电平有效21output EO; //使能输出端EO（选通输出端）22reg [2:0] dout;23reg GS, EO;24always @(din or EI)25if(EI) begin dout <= 3'b111; GS <= 1; EO <= 1; end //所有输出端被锁存在⾼电平26else if (din[7] == 0) begin dout <= 3'b000; GS <= 0; EO <= 1; end27else if (din[6] == 0) begin dout <= 3'b001; GS <= 0; EO <= 1; end28else if (din[5] == 0) begin dout <= 3'b010; GS <= 0; EO <= 1; end29else if (din[4] == 0) begin dout <= 3'b011; GS <= 0; EO <= 1; end30else if (din[3] == 0) begin dout <= 3'b100; GS <= 0; EO <= 1; end31else if (din[2] == 0) begin dout <= 3'b101; GS <= 0; EO <= 1; end32else if (din[1] == 0) begin dout <= 3'b110; GS <= 0; EO <= 1; end33else if (din[0] == 0) begin dout <= 3'b111; GS <= 0; EO <= 1; end34else if (din == 8'b11111111) begin dout <= 3'b111; GS <= 1; EO <= 0; end//芯⽚⼯作，但⽆编码输⼊35else begin dout <= 3'b111; GS <= 1; EO <= 1; end //消除锁存器（latch）36endmodule3738//EI = 0 表⽰允许编码，否则所有输出端被封锁在⾼电平（控制芯⽚⼯作）39//EO = 0 表⽰电路⼯作，但⽆编码输⼊（⽤于级联）40//GS = 0 表⽰电路⼯作，且有编码输⼊（判断输⼊端是否有输⼊）testbench：1 `timescale 1 ps/ 1 ps2module encoder_83_vlg_tst();3reg EI;4reg [7:0] din;5wire EO;6wire GS;7wire [2:0] dout;8 encoder_83 i1 (.EI(EI), .EO(EO), .GS(GS), .din(din), .dout(dout));9initial10begin11 EI = 1;12 din = 8'b11111111;13 #10 EI = 0;14 #10 din = 8'b01010101;15 #10 din = 8'b10101010;16 #10 din = 8'b11010101;17 #10 din = 8'b11101010;18 #10 din = 8'b11110101;19 #10 din = 8'b11111010;20 #10 din = 8'b11111101;21 #10 din = 8'b11111110;22 #10 din = 8'b11111111;23end24endmoduleView Codecase语句法1//8线-3线优先编码器设计（74LS148)2//3//EI | A7 A6 A5 A4 A3 A2 A1 A0 | Y2 Y1 Y0 GS EO4//0 | 0 x x x x x x x | 0 0 0 0 15//0 | 1 0 x x x x x x | 0 0 1 0 16//0 | 1 1 0 x x x x x | 0 1 0 0 17//0 | 1 1 1 0 x x x x | 0 1 1 0 18//0 | 1 1 1 1 0 x x x | 1 0 0 0 19//0 | 1 1 1 1 1 0 x x | 1 0 1 0 110//0 | 1 1 1 1 1 1 0 x | 1 1 0 0 111//0 | 1 1 1 1 1 1 1 0 | 1 1 1 0 112//0 | 1 1 1 1 1 1 1 1 | 1 1 1 1 013//1 | x x x x x x x x | 1 1 1 1 1141516module encoder_83_case (din, EI, GS, EO, dout);17input [7:0] din; //编码输⼊端data_in，低电平有效18input EI; //使能输⼊端EI（选通输⼊端），EI为 0 时芯⽚⼯作,即允许编码19output [2:0] dout; //编码输出端data_out20output GS; //⽚优先编码输出端，优先编码器⼯作⼯作状态标志GS，低电平有效21output EO; //使能输出端EO（选通输出端）22reg [2:0] dout;23reg GS, EO;24always @(din or EI)25if(EI)26begin dout <= 3'b111; GS <= 1; EO <= 1; end //所有输出端被锁存在⾼电平27else28casez (din) //建议⽤casez语句，casez把z/?匹配成任意。

流水灯电路硬件的功能和组成1 74LS148D74LS148是8线－3线优先编码器，共有 54/74148 和 54/74LS148两种线路结构型式，将8条数据线（0－7）进行 3 线(4-2-1)二进制（八进制）优先编码，即对最高位数据线进行译码。

利用选通端（EI）和输出选通端（EO）可进行八进制扩展。

功能表0－7 编码输入端(低电平有效)EI 选通输入端(低电平有效)A0、A1、A2 三位二进制编码输出信号即编码输出端(低电平有效)GS 片优先编码输出端即宽展端(低电平有效)EO 选通输出端，即使能输出端图72.2 74LS138D74LS138 为3 线－8 线译码器，共有 54/74S138和 54/74LS138 两种线路结构型式，其74LS138工作原理如下：当一个选通端（G1）为高电平，另两个选通端（/(G2A)和/(G2B)）为低电平时，可将地址端（A、B、C）的二进制编码在一个对应的输出端以低电平译出。

下图是它的原理结构图以及真值表：功能表表1无论从逻辑图还是功能表我们都可以看到74LS138的八个输出引脚,任何时刻要么全为高电平1--芯片处于不工作状态，要么只有一个为低电平0，其余7个输出引脚全为高电平1。

如果出现两个输出引脚同时为0的情况，说明该芯片已经损坏。

71LS138有三个附加的控制端、和。

当、时，输出为高电平（S＝1），译码器处于工作状态。

否则，译码器被禁止，所有的输出端被封锁在高电平。

这三个控制端也叫做“片选”输入端，利用片选的作用可以将多篇连接起来以扩展译码器的功能。

2 74LS04D是个6反相器，整形，隔离，提升带负载能力的作用，即给输入引脚处提供高阻特性，使信号上升时间（上升沿陡峭程度）不受内部电路影响单片机集成电路芯片，是采用超大规模集成电路技术把具有数据处理能力的中央处理器CPU 随机存储器RAM、只读存储器ROM、多种I/O口和中断系统、定时器/计时器等功能（可能还包括显示驱动电路、脉宽调制电路、模拟多路转换器、A/D转换器等电路）集成到一块硅片上构成的一个小而完善的微型计算机系统，在工业控制领域的广泛应用。

自我检测题1．组合逻辑电路任何时刻的输出信号，与该时刻的输入信号 有关 ，与以前的输入信号 无关 。

2．在组合逻辑电路中，当输入信号改变状态时，输出端可能出现瞬间干扰窄脉冲的现象称为 竞争冒险 。

3．8线—3线优先编码器74LS148的优先编码顺序是7I 、6I 、5I 、…、0I ，输出为2Y 1Y 0Y 。

输入输出均为低电平有效。

当输入7I 6I 5I …0I 为11010101时，输出2Y 1Y 0Y 为 010 。

4．3线—8线译码器74HC138处于译码状态时，当输入A 2A 1A 0=001时，输出07Y ~Y = 11111101 。

5．实现将公共数据上的数字信号按要求分配到不同电路中去的电路叫 数据分配器 。

6．根据需要选择一路信号送到公共数据线上的电路叫 数据选择器 。

7．一位数值比拟器，输入信号为两个要比拟的一位二进制数，用A 、B 表示，输出信号为比拟结果：Y (A ＞B ) 、Y (A ＝B )和Y (A ＜B )，那么Y (A ＞B )的逻辑表达式为B A 。

8．能完成两个一位二进制数相加，并考虑到低位进位的器件称为 全加器 。

9．多位加法器采用超前进位的目的是简化电路结构 × 。

〔√，× 〕 10．组合逻辑电路中的冒险是由于 引起的。

A ．电路未到达最简 B ．电路有多个输出C ．电路中的时延D ．逻辑门类型不同11．用取样法消除两级与非门电路中可能出现的冒险，以下说法哪一种是正确并优先考虑的？A ．在输出级加正取样脉冲B ．在输入级加正取样脉冲C ．在输出级加负取样脉冲D ．在输入级加负取样脉冲12．当二输入与非门输入为 变化时，输出可能有竞争冒险。

A ．01→10B ．00→10C ．10→11D ．11→0113．译码器74HC138的使能端321E E E 取值为 时，处于允许译码状态。

A ．011 B ．100 C ．101 D ．01014．数据分配器和 有着相同的根本电路结构形式。

实验名称 8线-3线编码器设计指导老师尚丽娜成绩专业电科班级 1102 姓名汪磊学号31102333一、实验目的1、学习QuartusII软件，学习使用硬件描述语言设计电路。

2、学习DE1平台基本构成，能够使用DE1平台进行简单设计。

二、实验要求使用QuartusII文本输入法设计8线-3线编码器。

使用QuartusII软件进行文本输入，并对设计电路进行仿真，并下载到硬件平台，自行定义硬件平台使用端口。

三、实验设备PC机、DE1硬件平台四、实验原理根据8线—3线编码器的真值表原理进行实验，下表为8线—3线编码器的真值表五、实验过程library ieee;use ieee.std_logic_1164.all;entity bm8_3 isport(a:in std_logic_vector(7 downto 0);b:out std_logic_vector(2 downto 0));end bm8_3;architecture zhang of bm8_3 isbeginprocess(a)begincase a iswhen"00000001"=>b<="000";when"00000010"=>b<="001";when"00000100"=>b<="010";when"00001000"=>b<="011";when"00010000"=>b<="100";when"00100000"=>b<="101";when"01000000"=>b<="110";when others=>b<="111";end case;end process;end zhang;六、实验结果该程序还存在一些不足，当出现10000000是和非正常输入的时候是一样的输出，所以我们进行了一些修改，修改程序与结果如下：library ieee;use ieee.std_logic_1164.all;entity e isport(a:in std_logic_vector(7 downto 0);b:out std_logic_vector(3 downto 0));end e;architecture zhang of e isbeginprocess(a)begincase a iswhen"00000001"=>b<="0000";when"00000010"=>b<="0001";when"00000100"=>b<="0010";when"00001000"=>b<="0011";when"00010000"=>b<="0100";when"00100000"=>b<="0101";when"01000000"=>b<="0110";when"10000000"=>b<="0111";when others=>b<="1111";end case;end process;end zhang;思考题一：思考题二：entity e isport(a:in bit_vector(7 downto 0);b:out bit_vector(3 downto 0)); end e;architecture zhang of e isbeginprocess(a)begincase a iswhen"00000001"=>b<="0000";when"00000010"=>b<="0001";when"00000100"=>b<="0010";when"00001000"=>b<="0011";when"00010000"=>b<="0100";when"00100000"=>b<="0101";when"01000000"=>b<="0110";when"10000000"=>b<="0111";when others=>b<="1111";end case;end process;end zhang;七、心得体会对操作更加熟练，加深对其的认识。

实验报告
学院：专业：班级：
8'b0100_0000:led<=3'b110; //当输入信号是位宽为8位的二进制数据01000000时,输出信号为位宽
为3位的二进制数据110
8'b1000_0000:led<=3'b111; //当输入信号是位宽为8位的二进制数据时,输出信号为位宽为3位的
二进制数据111
default :led<=3'b000; //当输入信号是位宽为8位的二进制数据00000001时,输出信号为位宽
为3位的二进制数据000
endcase //结束分支语句
end //结束循环语句
endmodule //结束模块
实
验
数
据
上图为波形仿真。

如图可知，当输入信号为00000001时，输出信号为000；输入信号为00000010时，输出信号为001；
输入信号为00000100时，输出信号为010；输入信号为00001000时，输出信号为011；输入信号为00010000时，输出信号为100；输入信号为00100000时，输出信号为101；输入信号为01000000时，输出信号为
注：各学院可根据教学需要对以上栏木进行增减。

表格内容可根据内容扩充。

PACKAGING INFORMATIONOrderable Device Status(1)PackageType PackageDrawingPins PackageQtyEco Plan(2)Lead/Ball Finish MSL Peak Temp(3)78027012A ACTIVE LCCC FK201TBD Call TI Level-NC-NC-NC7802701EA ACTIVE CDIP J161TBD Call TI Level-NC-NC-NC7802701FA ACTIVE CFP W161TBD Call TI Level-NC-NC-NC JM38510/36001B2A ACTIVE LCCC FK201TBD Call TI Level-NC-NC-NC JM38510/36001BEA ACTIVE CDIP J161TBD Call TI Level-NC-NC-NC JM38510/36001BFA ACTIVE CFP W161TBD Call TI Level-NC-NC-NC SN54148J OBSOLETE CDIP J16TBD Call TI Call TISN54LS148J ACTIVE CDIP J161TBD Call TI Level-NC-NC-NCSN74147N OBSOLETE PDIP N16TBD Call TI Call TISN74148J OBSOLETE CDIP J16TBD Call TI Call TISN74148N OBSOLETE PDIP N16TBD Call TI Call TISN74148N3OBSOLETE PDIP N16TBD Call TI Call TISN74LS147DR OBSOLETE SOIC D16TBD Call TI Call TISN74LS147N OBSOLETE PDIP N16TBD Call TI Call TISN74LS148D ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMSN74LS148DE4ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMSN74LS148DR ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMSN74LS148DRE4ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIM SN74LS148J OBSOLETE CDIP J16TBD Call TI Call TISN74LS148N ACTIVE PDIP N1625Pb-Free(RoHS)CU NIPDAU Level-NC-NC-NC SN74LS148N3OBSOLETE PDIP N16TBD Call TI Call TISN74LS148NE4ACTIVE PDIP N1625Pb-Free(RoHS)CU NIPDAU Level-NC-NC-NCSN74LS148NSR ACTIVE SO NS162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMSN74LS148NSRE4ACTIVE SO NS162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIM SNJ54148J OBSOLETE CDIP J16TBD Call TI Call TISNJ54148W OBSOLETE CFP W16TBD Call TI Call TISNJ54LS148FK ACTIVE LCCC FK201TBD Call TI Level-NC-NC-NC SNJ54LS148J ACTIVE CDIP J161TBD Call TI Level-NC-NC-NC SNJ54LS148W ACTIVE CFP W161TBD Call TI Level-NC-NC-NC (1)The marketing status values are defined as follows:ACTIVE:Product device recommended for new designs.LIFEBUY:TI has announced that the device will be discontinued,and a lifetime-buy period is in effect.NRND:Not recommended for new designs.Device is in production to support existing customers,but TI does not recommend using this part in a new design.PREVIEW:Device has been announced but is not in production.Samples may or may not be available.OBSOLETE:TI has discontinued the production of the device.(2)Eco Plan-The planned eco-friendly classification:Pb-Free(RoHS)or Green(RoHS&no Sb/Br)-please check/productcontent for the latest availability information and additional product content details.TBD:The Pb-Free/Green conversion plan has not been defined.Pb-Free(RoHS):TI's terms"Lead-Free"or"Pb-Free"mean semiconductor products that are compatible with the current RoHS requirements for all6substances,including the requirement that lead not exceed0.1%by weight in homogeneous materials.Where designed to be soldered at high temperatures,TI Pb-Free products are suitable for use in specified lead-free processes.Green(RoHS&no Sb/Br):TI defines"Green"to mean Pb-Free(RoHS compatible),and free of Bromine(Br)and Antimony(Sb)based flame retardants(Br or Sb do not exceed0.1%by weight in homogeneous material)(3)MSL,Peak Temp.--The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications,and peak solder temperature.Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.TI bases its knowledge and belief on information provided by third parties,and makes no representation or warranty as to the accuracy of such information.Efforts are underway to better integrate information from third parties.TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.TI and TI suppliers consider certain information to be proprietary,and thus CAS numbers and other limited information may not be available for release.In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s)at issue in this document sold by TI to Customer on an annual basis.IMPORTANT NOTICETexas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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