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1、用VHDL编写60进制计数器1用VHDL设计60进计数器。 设计一个BCD码60进计数器。要求实现同步，异步两种情况，且规定个位显示09，十位显示05，均用4位二进制数表示。用VHDL语言描述中小规模集成电路74LS169。 VHDL的源程序如下： ：同步，文件名为bcd60count LIBRARY ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity bcd60count is port(clk,bcd1wr,bcd10wr,cin: in std_logic; co: out std_logi
2、c; datain: in std_logic_vector(3 downto 0); bcd1p: out std_logic_vector(3 downto 0); bcd10p: out std_logic_vector(2 downto 0); end bcd60count; architecture behave of bcd60count is signal bcd1n: std_logic_vector(3 downto 0); signal bcd10n: std_logic_vector(2 downto 0); begin bcd1p=bcd1n; bcd10p=bcd10
3、n; kk1: process(clk,bcd1wr) begin if (bcd1wr=1) then bcd1n=datain; elsif(clkevent and clk=1) then if (cin=1) then if(bcd1n=1001 ) then bcd1n=0000; else bcd1n=bcd1n+1; end if; end if; end if; end process kk1; kk2: process(clk,bcd10wr) begin if (bcd10wr=1) then bcd10n=datain(2 downto 0); elsif(clkeven
4、t and clk=1) then if(cin=1) and (bcd1n=1001) then if(bcd10n=101) then bcd10n=000; else bcd10n=bcd10n+1; end if; end if; end if; end process kk2; kk3: process(bcd10n,bcd1n,cin) begin if(cin=1 and bcd1n=1001 and bcd10n=101) then co=1; else co=0; end if; end process kk3; end behave; 异步程序如下： LIBRARY iee
5、e; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity cou60 is port(clk,reset,cin : in std_logic; co : out std_logic; bcd1p : out std_logic_vector(3 downto 0); bcd10p : out std_logic_vector(2 downto 0); end cou60; architecture behave of cou60 is signal bcd1n: std_logic_vector(3 dow
6、nto 0); signal bcd10n: std_logic_vector(2 downto 0); begin bcd1p=bcd1n; bcd10p=bcd10n; kk1: process(clk) begin if(clkevent and clk=1) then if (reset=0) then bcd1n=0000; elsif (cin=1) then if(bcd1n=1001 ) then bcd1n=0000; else bcd1n=bcd1n+1; end if; end if; end if; end process kk1; kk2: process(clk)
7、begin if(clkevent and clk=1) then if (reset=0) then bcd10n=101; elsif(cin=1) and (bcd1n=1001) then if(bcd10n=001) then bcd10n=101; else bcd10n=bcd10n+1; end if; end if; end if; end process kk2; kk3: process(bcd10n,bcd1n,cin) begin if(cin=1 and bcd1n=1001 and bcd10n=001) then co=1; else co=0; end if; end process kk3; end behave;
