期末大作业课程设计实验报告设计题目：基于VHDL电子钟的设计目录一、概述 (3)1.1目的 (3)1.2课程设计的要求和功能 (3)二、总结 (3)2.1课程设计进行过程及步骤 (3)2.2所遇到的问题，如何解决问题 (15)2.3体会收获以及建议 (15)3.4参考资料（书，网络资料） (15)三、教师评语 (16)四、成绩 (16)一、概述1.1目的1. 基于CPLD系统模块板，设计一个电子钟。

来熟悉CPLD的工作原理以及对VHDL的使用。

2. 通过设计出一个电子钟具有校时功能，来巩固分频，键盘扫描，计数，动态扫描等知识内容。

1.2课程设计的要求和功能设计一个电子钟，能进行正常的时分秒计时功能，分别有六个数码管显示24小时，60分钟，60秒的计数器显示。

利用实验箱系统上的按键实现“校时”、“校分”功能：（1）按下“SA”键时，计时器快速递增，按24小时循环，进行时校正；（2）按下“SB”键时，计分器快速递增，按60分循环，进行分校正（3）按下“SC”键时，秒清零，进行秒校正；二、总结2.1课程设计进行及步骤1．设计提示系统框图见下2．系统结构设计描述（1）系统顶层文件1.顶层原理图见下2.各个模块的解释（1）五个输入量clk50MHz,SA,SB,SC,reset：其中clk50MHz为总体系统提供时钟，并且经过分频来分别对电子钟模块提供时钟，产生一秒一秒的进位信号，对显示模块的计数器提供时钟实现显示模块的扫描功能，对按键去抖动提供时钟，实现键盘扫描的功能。

SA,SB,SC用来控制按键，实现按键控制，SA是实现“时”加一，SB是实现“分”加一，SC是实现“秒”清零。

Reset是来控制按键功能的使能。

（2）按键功能模块三个输入chos ,date0,date1的功能是：chos接受来自按键的信号，若按键按下，则将date0的内容，也就是通过按键产生的脉冲来控制电子钟进行加一，若按键没有按下，则将“秒”分频信号接入电子钟的clk计数输入端，通过时钟脉冲来控制电子钟。

（3）电子钟计数模块有5个输入ci,nreset,load,clk,d[7..0]，作用分别是ci是使能端，直接接高电位，nreset是复位，load和d[7..0]是用来置数的，clk提供计数时钟，也就是一秒一个脉冲。

输出端有三个，co是进位功能，只有“秒”和“分”模块有效，qh[3..0],ql[3..0]是分位的数字输出端，一个是十位，一个是个位。

（4）显示模块输入端有qcnt接受来自计数器的计数实现显示扫描，d0h,d1h,d0m,d1m,d0s,d1s分别是接收的来自“秒”“分”“时”个位十位的数据，seg输出LCD的段扫描结果，SCAN输出LCD位扫描结果。

（2）系统各个模块的VHDL程序1．显示模块Library ieee;Use ieee.std_logic_1164.all;Use ieee.std_logic_unsigned.all;Use ieee.std_logic_arith.all;entity display isport(qcnt: IN integer range 0 to 7; --计数值输入d0h,d1h,d0m,d1m,d0s,d1s : IN integer range 0 to 9;--分位得到的十位数和个位数seg: OUT std_logic_vector(6 downto 0); --7位段码输出scan: OUT std_logic_vector(7 downto 0) --8为位码输出);end display;architecture a of display issignal data: integer range 0 to 10;beginprocess(qcnt,d0h,d1h,d0m,d1m,d0s,d1s)begincase qcnt iswhen 0 => scan <= "11111110"; data <= d0h;when 1 => scan <= "11111101"; data <= d1h;when 2 => scan <= "11111011"; data<= 10;when 3 => scan <= "11110111"; data <= d0m;when 4 => scan <= "11101111"; data <= d1m;when 5 => scan <= "11011111"; data<= 10;when 6 => scan <= "10111111"; data <= d0s;when others => scan <= "01111111"; data <= d1s;end case;end process;process(data)begincase data iswhen 0 => seg <= "0111111"; --0when 1 => seg <= "0000110"; --1when 2 => seg <= "1011011"; --2when 3 => seg <= "1001111"; --3when 4 => seg <= "1100110"; --4when 5 => seg <= "1101101"; --5when 6 => seg <= "1111101"; --6when 7 => seg <= "0000111"; --7when 8 => seg <= "1111111"; --8when 9 => seg <= "1100111"; --9when 10 => seg <="1000000"; --when others => seg <= "0000000";end case;end process;end a;动态显示计数器部分：LIBRARY ieee;USE ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;-- Entity DeclarationENTITY qcnt_display IS-- {{ALTERA_IO_BEGIN}} DO NOT REMOVE THIS LINE!PORT(clk : IN STD_LOGIC;qcnt : buffer STD_LOGIC_VECTOR(2 downto 0) );-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE!END qcnt_display ;-- Architecture BodyARCHITECTURE cnt_architecture OF qcnt_display IS BEGINPROCESS (clk)BEGINIF (clk'EVENT AND clk = '1') THENqcnt <= qcnt+1;END IF;END PROCESS;END cnt_architecture;2. 分位计数模块“秒”，“分”部分：LIBRARY ieee;USE ieee.std_logic_1164.all;USE ieee.std_logic_unsigned.all;-- Entity DeclarationENTITY counter60 IS-- {{ALTERA_IO_BEGIN}} DO NOT REMOVE THIS LINE!PORT(ci: in std_logic;nreset : IN STD_LOGIC:='1';load: IN STD_LOGIC;clk : IN STD_LOGIC;d :in std_logic_vector(7 downto 0);co: out std_logic;qh: buffer std_logic_vector(3 downto 0);ql : buffer std_logic_vector(3 downto 0));-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE! END counter60;-- Architecture BodyARCHITECTURE counter_architecture OF counter60 ISBEGINco<='1' when ( qh ="0101" and ql ="1001" and ci ='1') else '0'; process (clk,nreset)beginif (nreset='0') thenqh <="0000";ql <="0000";elsif rising_edge(clk) thenif (load ='1') thenqh<= d(7 downto 4);ql<= d(3 downto 0);elsif(ci='1') thenif(ql=9) thenql<="0000";if(qh=5) thenqh<="0000";elseqh<=qh+1;end if;elseql<=ql+1;end if;end if;end if;end process;END counter_architecture;“时”部分：LIBRARY ieee;USE ieee.std_logic_1164.all;USE ieee.std_logic_unsigned.all;-- Entity DeclarationENTITY counter24 IS-- {{ALTERA_IO_BEGIN}} DO NOT REMOVE THIS LINE!PORT(ci: in std_logic;nreset : IN STD_LOGIC:='1';load: IN STD_LOGIC;clk : IN STD_LOGIC;d :in std_logic_vector(7 downto 0);co: out std_logic:='0';qh: buffer std_logic_vector(3 downto 0);ql : buffer std_logic_vector(3 downto 0));-- {{ALTERA_IO_END}} DO NOT REMOVE THIS LINE! END counter24;-- Architecture BodyARCHITECTURE counter_architecture OF counter24 IS BEGIN--co<='1' when ( qh ="0010" and ql ="0011" and ci ='1') else '0'; process (clk,nreset)begin--if (nreset='0') then--qh <="0000";-- ql <="0000";if rising_edge(clk) thenif (load ='1') thenqh<= d(7 downto 4);ql<= d(3 downto 0);elsif(ci='1') thenif(qh=0 or qh=1) thenif(ql=9) thenql<="0000";if(qh=2) thenqh<="0000";elseqh<=qh+1;end if;elseql<=ql+1;end if;elseif(ql=3) thenql<="0000";if(qh=2) thenqh<="0000";elseqh<=qh+1;end if;elseql<=ql+1;end if;end if;end if;end if;end process;END counter_archit ecture;3. 分频模块Library ieee;Use ieee.std_logic_1164.all;Use ieee.std_logic_unsigned.all;Use ieee.std_logic_arith.all;Entity fdiv_duo isport(clkin: IN std_logic;clkout_200HZ: buffer std_logic;--键盘去抖动clkout_1KHZ : buffer std_logic;--显示模块计数器 clkout_10HZ : buffer std_logic;--按键选择clkout_1HZ : buffer std_logic --计数器模块);End fdiv_duo;Architecture a of fdiv_duo issignal cnt_1HZ : natural range 0 to 24999999 ;signal cnt_10HZ : natural range 0 to 249999999;signal cnt_1KHZ : natural range 0 to 24999;signal cnt_200HZ : natural range 0 to 124999;Beginprocess(clkin)beginif(clkin'event and clkin='1') thenif cnt_1HZ=24999999 thencnt_1HZ<= 0;clkout_1HZ<= not clkout_1HZ;elsecnt_1HZ<= cnt_1HZ + 1;end if;if cnt_10HZ=249999999 thencnt_10HZ <= 0;clkout_10HZ <= not clkout_10HZ;elsecnt_10HZ <= cnt_10HZ + 1;end if;if cnt_1KHZ=24999 thencnt_1KHZ<= 0;clkout_1KHZ <=not clkout_1KHZ;elsecnt_1KHZ <=cnt_1KHZ + 1;end if;if cnt_200HZ=124999 thencnt_200HZ <= 0;clkout_200HZ<= not clkout_200HZ; elsecnt_200HZ <= cnt_200HZ + 1;end if;end if;end process;End a;4. 键盘控制模块时钟和分钟的键盘去抖动和“增益”，“清零”控制部分：Library ieee;Use ieee.std_logic_1164.all;Use ieee.std_logic_unsigned.all;Use ieee.std_logic_arith.all;Entity debounce isport(clk200hz ,reset : IN std_logic; --200HZ时钟din : IN std_logic;dout : OUT std_logic);End debounce;architecture a of debounce istype state is (S0, S1, S2);--定义状态机类型signal current : state;beginprocess (clk200hz,reset,din)beginif(reset='1') then --状态机复位dout输出信号复位current<=S0;dout<='1';elsif(clk200hz'event and clk200hz='1') thencase current iswhen S0=>dout<='1';if(din='0') thencurrent<=S1;elsecurrent<=S0;end if;when S1=>dout<='1';if(din='0')thencurrent<=S2;elsecurrent<=S0;end if;when S2=>dout<='0';if(din='0') thencurrent<=S2;elsecurrent<=S0;end if;when others=>dout<='1';current<=S0;end case;end if;end process;end a;作用解释：当检测到按键被按下时，将按键的输出直接给计数模块的时钟控制通过按键控制计数时钟从而实现“增益”功能，如果没有检测到有效按键，“时”和“分”计数模块就受进位信号的控制。