EDA用VHDL语言设计一个2-4译码器

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1、2-4译码器LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIEEE.STD_LOGIC_ARITH.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYdecoder2_4ISPORT(a:INSTD_LOGIC_VECTOR(1DOWNTO0);s:OUTSTD_LOGIC_VECTOR(3DOWNTO0));ENDdecoder2_4;ARCHITECTUREBehavioralOFdecoder2_4_tISBEGINPROCESS(sel)BEGINCASEaISWHEN"00"=>s

2、<=”0001”;WHEN"01"=>s<=”0010”;WHEN"10"=>s<=”0100”;WHEN"11"=>s<=”1000“;WHENOTHERS=>s<=’’0000”ENDCASE;ENDPROCESS;ENDBrhavioral;4选1数据选择器LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIEEE.STD_LOGIC_ARITH.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYsel4ISPROT(d:INSTD_LOGIC_VECTOR(3DOWNTO0);a:INS

3、TD_LOGIC_VECTOR(1DOWNTO0);s:OUTSTD_LOGIC);ENDsel4:ARCHITECTUREBehavioralOFsel4ISBEGINROCESS(a,d)BEGINCASEaISWHEN"00"=>s<=d(0)WHEN"01"=>s<=d(1)WHEN"10"=>s<=d(2)WHEN"11"=>s<=d(3)“;WHENOTHERS=>s<=’Z’ENDCASE;ENDPROCESS;ENDBrhavioral;100进制加法计数器LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIE

4、EE.STD_LOGIC_ARITH.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYcounterISPORT(clk,en,load,rst:INSTD_LOGICd;INSTD_LOGIC_VECTOR(6DOWNTO0);q:OUTSTD_LOGIC_VECTOR(6DOWNTO0):ENDcounter100;ARCHTECTUREBehavioralOFcounter100ISsignalqtemp:STD_LOGIC_VECTOR(6DOWNTO0);BEGINPROCESS(clk,d,en,load,rst)

5、BEGINIFrst=’1’THENqtemp<=”00000000”;ELSIFrising-edge(clk)THENIFen=’1’THENIFload=’1’THENqtemp<=d,ELSIFqtemp=”1100011”THENqtemp<=”00000000”;ELSIFqtemp<=qtemp+’1;ENDIF;ENDIF;ENDIF;ENDPROCESS;q<=qtemp;ENDBehavioral;8位从高至低串入串出移位寄存器LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIEEE.STD_LOGIC

6、_ARITH.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYshift.registerISPORT(d,clk:INSTD_LOGIC;q:OUTSTD_LOGIC);ENDdshift.register;ARCHITECTUREBehavioralOFshift.registerISsignalqtemp:STD_LOGIC_VECTOR(7DOWNTO0);BEGINPROCESS(d,clk)BEGINIFrising-edge(clk)THENq<=dtemp(0);dtemp<=d&dtemp(7DOWNTO1)

7、;ENDIF;ENDPROCESS;ENDBehavioral;状态机LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIEEE.STD_LOGIC_ARITH.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYfsmISPORT(tin,clk:INSTD_LOGIC;yout:OUTSTD_LOGIC_VECTOR(1DOWNTO0));ENDfsm;ARCHITECTUREBehavioralOFfsmISTYPEstate-typeIS(S0,S1,S2)signalstate,next

8、_state:state_type;B