ORG 0000H
JMP BEGIN
ORG 0030H
TABLE: ; 共阴极数码管显示代码表
DB 3FH,06H,5BH,4FH,66H ;01234
DB 6DH,7DH,07H,7FH,6fh ;56789
DELAY: MOV R5,#20
LOOP4: MOV R6,#50H ;延时20X20ms
LOOP5: MOV R7,#100
DJNZ R7,$
DJNZ R6,LOOP5
DJNZ R5,LOOP4
RET
;---------------------------------------
BEGIN: MOV P2,#0FFH ;P2口置高电平，准备接收信号
MOV R4,#0
MOV A,R4 ;R4位标志值送A寄存器
AGAIN: MOV DPTR,#TABLE
MOVC A,@A+DPTR
MOV P1,A
LOOP1: MOV A,P3 ; 接收p3口的抢答信号
CPL A
JZ LOOP1
LOOP2: RRC A ;有人抢答信号则逐次移动判断哪一位抢答
INC R4
JNC LOOP2
;********************
MOV A,R4
MOVC A,@A+DPTR ;找到相应位显示代码
MOV P1,A
LEDDIS:
MOV A,#0FFH
CLR C
LEDDIS1:
RLC A
DJNZ R4,LEDDIS1
MOV P0,A
LOOP3: JNB P3.3,BEGIN ;若主持人按下复位信号键，则转向主程序
CPL P3.7 ;若没按复位信号键，给出高低信号驱动蜂鸣器
LCALL DELAY ;调用延时子程序
SJMP LOOP3 ;反复间隔0.4s变化，驱动蜂鸣器
END
各模块VHDL源代码
1、抢答鉴别模块FENG的VHDL源程序
--feng.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY FENG IS
PORT(CP,CLR:IN STD_LOGIC;
Q :OUT STD_LOGIC);
END FENG;
ARCHITECTURE FENG_ARC OF FENG IS
BEGIN
PROCESS(CP,CLR)
BEGIN
IF CLR='0'THEN
Q<='0';
ELSIF CP'EVENT AND CP='0'THEN
Q<='1';
END IF;
END PROCESS;
END FENG_ARC;
2、片选信号产生模块SEL的VHDL源程序
--sel.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY SEL IS
PORT(CLK:IN STD_LOGIC;
a:OUT INTEGER RANGE 0 TO 7);
END SEL;
ARCHITECTURE SEL_ARC OF SEL IS 片选信号产生模块SEL
BEGIN
PROCESS(CLK)
VARIABLE AA:INTEGER RANGE 0 TO 7;
BEGIN
IF CLK'EVENT AND CLK='1'THEN
AA:=AA+1;
END IF;
A<=AA;
END PROCESS;
END SEL_ARC;
3、锁存器模块LOCKB的VHDL源程序
-lockb.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY LOCKB IS
PORT(D1,D2,D3,D4:IN STD_LOGIC;
CLK,CLR:IN STD_LOGIC;
Q1,Q2,Q3,Q4,ALM:OUT STD_LOGIC);
END LOCKB;
ARCHITECTURE LOCK_ARC OF LOCKB IS
BEGIN
PROCESS(CLK)
BEGIN
IF CLR='0'THEN
Q1<='0';
Q2<='0';
Q3<='0';
Q4<='0';
ALM<='0'; 模块LOCKB
ELSIF CLK'EVENT AND CLK='1'THEN
Q1<=D1;
Q2<=D2;
Q3<=D3;
Q4<=D4;
ALM<='1';
END IF;
END PROCESS;
END LOCK_ARC;
4、转换模块CH41A的VHDL源程序
--ch41a..vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY CH41A IS
PORT(D1,D2,D3,D4:IN STD_LOGIC;
Q:OUT STD_LOGIC_VECTOR(3 DOWNTO 0));
END CH41A;
ARCHITECTURE CH41_ARC OF CH41A IS 转换模块CH41A
BEGIN
PROCESS(D1,D2,D3,D4)
VARIABLE TMP:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
TMP:=D1&D2&D3&D4;
CASE TMP IS
WHEN "0111"=>Q<="0001";
WHEN "1011"=>Q<="0010";
WHEN "1101"=>Q<="0011";
WHEN "1110"=>Q<="0100";
WHEN OTHERS=>Q<="1111";
END CASE;
END PROCESS;
END CH41_ARC;
5、3选1模块CH31A的VHDL源程序
--ch31a.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY CH31A IS
PORT(SEL:IN STD_LOGIC_VECTOR(2 DOWNTO 0);
D1,D2,D3:IN STD_LOGIC_VECTOR(3 DOWNTO 0);
Q : OUT STD_LOGIC_VECTOR(3 DOWNTO 0));
END CH31A;
ARCHITECTURE CH31_ARC OF CH31A IS
BEGIN
PROCESS(SEL,D1,D2,D3)
BEGIN
CASE SEL IS
WHEN "000"=>Q<=D1;
WHEN "001"=>Q<=D2;
WHEN "111"=>Q<=D3;
WHEN OTHERS=>Q<="1111";
END CASE;
END PROCESS;
END CH31_ARC;
6、倒计时模块COUNT的VHDL源程序
倒计时模块COUNT如图16-7所示，该模块实现答题时间的倒计时，在计满100s后送出声音提示。
--count.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY COUNT IS
PORT(CLK,EN:IN STD_LOGIC; 倒计时 模块COUNT
H,L:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
SOUND:OUT STD_LOGIC);
END COUNT;
ARCHITECTURE COUNT_ARC OF COUNT IS
BEGIN
PROCESS(CLK,EN)
VARIABLE HH,LL:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
IF CLK'EVENT AND CLK='1'THEN
IF EN='1'THEN
IF LL=0 AND HH=0 THEN
SOUND<='1';
ELSIF LL=0 THEN
LL:="1001";
HH:=HH-1;
ELSE
LL:=LL-1;
END IF;
ELSE
SOUND<='0';
HH:="1001";
LL:="1001";
END IF;
END IF;
H<=HH;
L<=LL;
END PROCESS;
END COUNT_ARC;
7、显示译码模块DISP的VHDL源程序
--disp.vhd
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY DISP IS 显示译码模块DISP
PORT(D:IN STD_LOGIC_VECTOR(3 DOWNTO 0);
Q:OUT STD_LOGIC_VECTOR(6 DOWNTO 0));
END DISP;
ARCHITECTURE DISP_ARC OF DISP IS
BEGIN
PROCESS(D)
BEGIN
CASE D IS
WHEN"0000"=>Q<="0111111";
WHEN"0001"=>Q<="0000110";
WHEN"0010"=>Q<="1011011";
WHEN"0011"=>Q<="1001111";
WHEN"0100"=>Q<="1100110";
WHEN"0101"=>Q<="1101101";
WHEN"0110"=>Q<="1111101";
WHEN"0111"=>Q<="0100111";
WHEN"1000"=>Q<="1111111";
WHEN"1001"=>Q<="1101111";
WHEN OTHERS=>Q<="0000000";
END CASE;
END PROCESS;
END DISP_ARC;
