8421碼十進(jìn)制計(jì)數(shù)器

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8421碼十進(jìn)制計(jì)數(shù)器：

LIBRARYIEEE;

USEIEEE.STD_LOGIC_1164.ALL;

USEIEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITYGKY07P10IS

PORT(clk,reset:INSTD_LOGIC;

q:OUTSTD_LOGIC_VECTOR(3DOWNTO0));

ENDGKY07P10;

ARCHITECTUREstrucOFGKY07P10IS

SIGNALq_temp:STD_LOGIC_VECTOR(3DOWNTO0);

BEGIN

PROCESS(clk)

BEGIN

IF(clk'EVENTANDclk='1')THEN

IFreset='1'THEN

q_temp=0000;

ELSIFq_temp=1001THEN

q_temp=0000;

ELSE

q_temp=q_temp+1;

ENDIF;

ENDIF;

ENDPROCESS;

q=q_temp;

ENDstruc;

從狀態(tài)‘0000’到狀態(tài)‘1001’，然后再跳回‘0000’，異步復(fù)位要馬上復(fù)位。

分頻器：

LIBRARYIEEE;

USEIEEE.STD_LOGIC_1164.ALL;

USEIEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITYGKY07P13IS

PORT(clk,clear:INSTD_LOGIC;

clk_out:OUTSTD_LOGIC);

ENDGKY07P13;

ARCHITECTUREstrucOFGKY07P13IS

SIGNALtemp:INTEGERRANGE0TO11;

BEGIN

p1:PROCESS(clear,clk)

BEGIN

IFclear='0'THEN

temp=0;

ELSIFclk'EVENTANDclk='1'THEN

IFtemp=11THEN

temp=0;

ELSE

temp=temp+1;

ENDIF;

ENDIF;

ENDPROCESSp1;

p2:PROCESS(temp)

BEGIN

IFtemp6THEN

clk_out='0';

ELSE

clk_out='1';

ENDIF;

ENDPROCESSp2;

ENDstruc;

很重要的一個器件，但是設(shè)計(jì)難度并不很高，首先是模為12的計(jì)數(shù)，然后是占空比50%。

LIBRARYIEEE;

USEIEEE.STD_LOGIC_1164.ALL;

ENTITYLEDIS

PORT(a:INSTD_LOGIC_VECTOR(3DOWNTO0);

b:OUTSTD_LOGIC_VECTOR(6DOWNTO0));

ENDLED;

ARCHITECTURELEDarchOFLEDIS

BEGIN

PROCESS(a)

BEGIN

CASEaIS

WHEN0000=b=1111110;--0

WHEN0001=b=0110000;--1

WHEN0010=b=1101101;--2

WHEN0011=b=1111001;--3

WHEN0100=b=0110011;--4

WHEN0101=b=1011011;--5

WHEN0110=b=1011111;--6

WHEN0111=b=1110000;--7

WHEN1000=b=1111111;--8

WHEN1001=b=11110