1、process(clk,clr,pre,c)begin if(clr=1)then q_tmp=0;elsif(pre=1)then q_tmp=1;elsif rising_edge(clk)then if(ce=1)then q_tmp=d;else q_tmp=q_tmp;end if;end if;end process;end rtl;输入输入输出输出RSCEJKCQ1XXXX001XXX1000XXX无变化无变化00100X无变化无变化00101000111翻转翻转001101 if(r=1)then q_tmp=0;elsif(s=1)then q_tmp=1;elsif ris
2、ing_edge(clk)then if(ce=0)then q_tmp=q_tmp;else if(j=0 and k=1)then q_tmp=0;elsif(j=1 and k=0)then q_tmp=1;elsif(j=1 and k=1)then q_tmp=not q_tmp;end if;end if;end process;end rtl;输入输出RSCQ00无变化01110011无变化process(clk)begin if rising_edge(clk)then if(s=1 and r=0)then q_tmp=1;elsif(s=0 and r=1)then q_t
3、mp=0;elsif(s=0 and r=0)then q_tmp=q_tmp;else null;end if;end if;end process;end rtl;architecture Behavioral of mod5cnt isbegin process(clk,clr)begin if(clr=1)then q=000;elsif(rising_edge(clk)then if(q=100)then q=000;else q=q+1;end if;end if;end process;end Behavioral;architecture Behavioral of clkdi
4、v issignal q:std_logic_vector(24 downto 0);begin process(clr,clk)begin if(clr=1)then q0);elsif(rising_edge(clk)then q=q+1;end if;end process;clk190=q(17);-190Hz clk48=q(19);-47.7Hzend Behavioral;architecture Behavioral of ring_shiftreg4 isbegin process(clr,clk)begin if(clr=1)then q=0001;elsif(rising
5、_edge(clk)then q(3)=q(0);q(2 downto 0)=q(3 downto 1);end if;end process;end Behavioral;architecture Behavioral of debounce4 issignal delay1,delay2,delay3:std_logic_vector(3 downto 0);begin process(cclk,clr,inp)begin if(clr=1)then delay1=0000;delay2=0000;delay3=0000;elsif(rising_edge(cclk)then delay1
6、=inp;delay2=delay1;delay3=delay2;end if;end process;outp=delay1 and delay2 and delay3;end Behavioral;architecture Behavioral of clock_pluse issignal delay1,delay2,delay3:std_logic;begin process(clr,cclk)begin if(clr=1)then delay1=0;delay2=0;delay3=0;elsif(rising_edge(cclk)then delay1=inp;delay2=dela
7、y1;delay3=delay2;end if;end process;outp=delay1 and delay2 and(not delay3);end Behavioral;%100周期占空占空比architecture Behavioral of pwm4 issignal count:STD_LOGIC_VECTOR(3 downto 0);signal set,reset:std_logic;Beginset=not(count(0)or count(1)or count(2)or count(3);process(clk,clr)begin if(clr=1)then count
8、=0000;elsif(rising_edge(clk)then if(count=period1-1)then count=0000;else count=count+1;end if;end if;end process;process(clk)begin if(rising_edge(clk)then if(set=1)then pwm=1;end if;if(reset=1)then pwm=0;end if;end if;end process;end Behavioral;图4.16 ROM的结构图图4.17 单端口RAM的结构十进制数十进制数二进制码二进制码Gray码码Johns
9、on码码One-hot吗吗000000000000110010010010102010011011100301101011110004100110510111161101017111100architecture Behavioral of seqdeta istype state is(s0,s1,s2,s3,s4);-状态声明signal present_state,next_state:state;beginprocess(clr,clk)begin if(clr=1)then -状态寄存器 present_state=s0;elsif rising_edge(clk)then pres
10、ent_state=next_state;end if;end process;architecture Behavioral of seqdetb istype state is(s0,s1,s2,s3);-定义状态signal present_state,next_state:state;beginprocess(clr,clk)-状态寄存器begin if(clr=1)then present_state=s0;elsif rising_edge(clk)then present_state if(din=1)then next_state=s1;else next_state next_state=s0;end case;end process;该状态图包含：1）四个状态：s1，s2，s3，s4;2）5个转移；3）1个输入“x1”;4）1个输出“outp”;
