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1、十五计数器library ieee;use ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;ENTITY fiveteencout ISPORT(clk,reset,enable : IN std_logic; count : OUT std_logic_vector(3 downto 0);END fiveteencout;ARCHITECTURE counter OF fiveteencout ISSIGNAL count_int:std_logic_vector(0 to 3);BEGINPROCESS(clk,reset)
2、BEGINWAIT UNTIL rising_edge(clk);IF reset = 1 THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1110) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1101) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1100) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1011) THENcount_int 0);ELSIF ena
3、ble = 1 THENIF(count_int=1010) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1001) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=1000) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=111) THENcount_int 0);ELSIF enable = 1 THENIF(count_int=101) THENcount_int 0);ELSIF enable = 1 THENIF(co
4、unt_int=11) THENcount_int=00;ELSEcount_int = count_int 1;-ELSE- NULL ;-IF (count_int=1001) THEN-count_int=0000;END IF;END IF;END PROCESS;count = count_int;- IF (reset=0) then-q=0000;-ELSIF(clkevent and clk=1) THEN-q=q 1;-IF (q=1001) then-q=0000;-END IF;-IF (reset=1)THEN-q=00;-ELSIF-wait until (clkev
5、ent and clk=1);-WAIT UNTIL (clkEVENT AND clk = 1);-WAIT UNTIL (clockEVENT AND clock = 1);- q=q 1;-end if;-count=q;- WAIT UNTIL clock = 1;-if (clockevent and clock=1)then-WAIT UNTIL rising_edge(clock);-clockevent and clock=1;-count = 0;-WAIT UNTIL (clockEVENT AND clock = 1);-WAIT riseedge clock = 1;-if (clockevent and clock=1) then-WAIT UNTIL rising_edge(clock);-count = 1;-WAIT UNTIL (clockEVENT AND clock = 1);-WAIT UNTIL clock = 1;-if (clockevent and clock=1)then-WAIT UNTIL rising_edge(clock);-count = 2;-end if;-end if;-end if;- END PROCESS;END counter;
