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1、第六章第六章 VHDLVHDL综合应用综合应用l l数字电子时钟显示电路数字电子时钟显示电路6 个七段数码管SEGOUT ( 8 ) CLR 时钟显示电路方框图CP FPGASELOUT ( 6 ) 24进制计数器60进制计数器60进制计数器BCD 七段译码电路BCD 选择BCD(8)BIN(6)6 个七段数码管扫描电路 S(3) SEG (8) NUM(4) BCD (3-0) BCD (7-4) ENB (0) ENB (1) ENB (2) DBHDBMDBSBIN ( 6 ) 时钟显示电路方框图SEC CLR CYH CYS CYM 分频器QQCP 38译码PROCESS (CP)Be
2、ginIF CPEvent AND CP=1 thenDLY = Q(21);Q = Q+1;END IF;END PROCESS; Free_Counter : Block Signal Q: STD_LOGIC_VECTOR(24 DOWNTO 0);Signal DLY : STD_LOGIC;Begin PROCESS (CP)BeginIF CPEvent AND CP=1 thenDLY = Q(21);Q = Q+1;END IF;END PROCESS; SEC = Q(21) AND NOT DLY;-about 1Hz S = Q(15 DOWNTO 13);-about
3、250 HzENB = 001 WHEN (S=0 OR S=1) ELSE010 WHEN (S=2 OR S=3) ELSE100 WHEN (S=4 OR S=5) ELSE000;BIN = DBS WHEN ENB = 001 ELSEDBM WHEN ENB = 010 ELSEDBH WHEN ENB = 100 ELSE000000;End Block Free_Counter;-主文件声明代码COMPONENT COUNTER60PORT( CP: IN STD_LOGIC; BIN: OUTSTD_LOGIC_VECTOR (5 DOWNTO 0); S: IN STD_L
4、OGIC;CLR: IN STD_LOGIC;EC: IN STD_LOGIC;CY60 : OUT STD_LOGIC);END COMPONENT;- 子文件定义代码-*LIBRARY IEEE;USE IEEE.STD_LOGIC_UNSIGNED.ALL;-*ENTITY COUNTER60 ISPORT(CP : IN STD_LOGIC;BIN: OUT STD_LOGIC_VECTOR (5 DOWNTO 0);S : IN STD_LOGIC;CLR : IN STD_LOGIC;EC : IN STD_LOGIC;CY60 : OUT STD_LOGIC);END COUNT
5、ER60;- 子文件定义代码ARCHITECTURE a OF COUNTER60 ISSIGNAL Q : STD_LOGIC_VECTOR (5 DOWNTO 0) ;SIGNAL RST, DLY : STD_LOGIC;BEGIN PROCESS (CP,RST)BEGINIF RST = 1 THENQ = 000000;ELSIF CPevent AND CP = 1 THENDLY = Q(5);IF EC = 1 THENQ = Q+1;END IF; END IF;END PROCESS; CY60 = NOT Q(5) AND DLY;RST = 1 WHEN Q=60 O
6、R CLR=1 ELSE 0;BIN = Q WHEN S = 1 ELSE 000000;END a;-主文件声明代码COMPONENT COUNTER24PORT( CP: IN STD_LOGIC; BIN: OUTSTD_LOGIC_VECTOR (5 DOWNTO 0); S: IN STD_LOGIC;CLR: IN STD_LOGIC;EC: IN STD_LOGIC;CY60 : OUT STD_LOGIC);END COMPONENT;- 子文件定义代码-*LIBRARY IEEE;USE IEEE.STD_LOGIC_1164.ALL;USE IEEE.STD_LOGIC_
7、UNSIGNED.ALL;-*ENTITY COUNTER24 ISPORT(CP : IN STD_LOGIC;BIN: OUT STD_LOGIC_VECTOR (5 DOWNTO 0);S : IN STD_LOGIC;CLR : IN STD_LOGIC;EC : IN STD_LOGIC;CY24 : OUT STD_LOGIC);END COUNTER24;- 子文件定义代码ARCHITECTURE a OF COUNTER24 ISSIGNAL Q : STD_LOGIC_VECTOR (4 DOWNTO 0) ;SIGNAL RST, DLY : STD_LOGIC;BEGIN
8、PROCESS (CP,RST)BEGINIF RST = 1 THENQ = 00000;ELSIF CPevent AND CP = 1 THENDLY = Q(4);IF EC = 1 THENQ = Q+1;END IF; END IF;END PROCESS; CY24 = NOT Q(4) AND DLY;RST = 1 WHEN Q=24 OR CLR=1 ELSE 0;BIN = (0 & Q) WHEN S = 1 ELSE 000000;END a;Binary_BCD : BlockBEGINBCD =00000000 WHEN BIN = 0 ELSE00000001
9、WHEN BIN = 1 ELSE00000010 WHEN BIN = 2 ELSE00000011 WHEN BIN = 3 ELSE00000100 WHEN BIN = 4 ELSE00000101 WHEN BIN = 5 ELSE00000110 WHEN BIN = 6 ELSE00000111 WHEN BIN = 7 ELSE00001000 WHEN BIN = 8 ELSE00001001 WHEN BIN = 9 ELSE00010000 WHEN BIN = 10 ELSE00010001 WHEN BIN = 11 ELSE00010010 WHEN BIN = 1
10、2 ELSE00010011 WHEN BIN = 13 ELSE00010100 WHEN BIN = 14 ELSE00010101 WHEN BIN = 15 ELSE00010110 WHEN BIN = 16 ELSE00010111 WHEN BIN = 17 ELSE00011000 WHEN BIN = 18 ELSE00011001 WHEN BIN = 19 ELSE00100000 WHEN BIN = 20 ELSE00100001 WHEN BIN = 21 ELSE00100010 WHEN BIN = 22 ELSE00100011 WHEN BIN = 23 E
11、LSE00100100 WHEN BIN = 24 ELSE00100101 WHEN BIN = 25 ELSE00100110 WHEN BIN = 26 ELSE00100111 WHEN BIN = 27 ELSE00101000 WHEN BIN = 28 ELSE00101001 WHEN BIN = 29 ELSE00110000 WHEN BIN = 30 ELSE00110001 WHEN BIN = 31 ELSE00110010 WHEN BIN = 32 ELSE00110011 WHEN BIN = 33 ELSE00110100 WHEN BIN = 34 ELSE
12、00110101 WHEN BIN = 35 ELSE00110110 WHEN BIN = 36 ELSE00110111 WHEN BIN = 37 ELSE00111000 WHEN BIN = 38 ELSE00111001 WHEN BIN = 39 ELSE01000000 WHEN BIN = 40 ELSE01000001 WHEN BIN = 41 ELSE01000010 WHEN BIN = 42 ELSE01000011 WHEN BIN = 43 ELSE01000100 WHEN BIN = 44 ELSE01000101 WHEN BIN = 45 ELSE010
13、00110 WHEN BIN = 46 ELSE01000111 WHEN BIN = 47 ELSE01001000 WHEN BIN = 48 ELSE01001001 WHEN BIN = 49 ELSE01010000 WHEN BIN = 50 ELSE01010001 WHEN BIN = 51 ELSE01010010 WHEN BIN = 52 ELSE01010011 WHEN BIN = 53 ELSE01010100 WHEN BIN = 54 ELSE01010101 WHEN BIN = 55 ELSE01010110 WHEN BIN = 56 ELSE010101
14、11 WHEN BIN = 57 ELSE01011000 WHEN BIN = 58 ELSE01011001 WHEN BIN = 59 ELSE00000000;END Block Binary_BCD;SELECT_BCD : BlockBEGINNUM = BCD(3 DOWNTO 0) WHEN (S=0 OR S=2 OR S=4) ELSEBCD(7 DOWNTO 4); End Block SELECT_BCD;SEVEN_SEGMENT : BlockBegin -gfedcbaSEG = 0111111 WHEN NUM = 0 ELSE0000110 WHEN NUM
15、= 1 ELSE 1011011 WHEN NUM = 2 ELSE1001111 WHEN NUM = 3 ELSE1100110 WHEN NUM = 4 ELSE1101101 WHEN NUM = 5 ELSE1111101 WHEN NUM = 6 ELSE0000111 WHEN NUM = 7 ELSE 1111111 WHEN NUM = 8 ELSE1101111 WHEN NUM = 9 ELSE1110111 WHEN NUM = 10 ELSE1111100 WHEN NUM = 11 ELSE0111001 WHEN NUM = 12 ELSE1011110 WHEN
16、 NUM = 13 ELSE1111001 WHEN NUM = 14 ELSE1110001 WHEN NUM = 15 ELSE0000000;End Block SEVEN_SEGMENT;延迟与微分电路延迟与微分电路用途：用途：将宽脉冲减小为一个时钟周期的脉将宽脉冲减小为一个时钟周期的脉 冲宽度；消除小于一个周期的脉冲冲宽度；消除小于一个周期的脉冲CPINDCPQ#QDCPQ#QOUT延迟与微分电路延迟与微分电路时序图：CPINQ1Q2OUTCPINDCPQ#QDCPQ#QOUT同步计数器电路同步计数器电路用途：用途：消除竞争冒险；消除延时误差消除竞争冒险；消除延时误差CPINDCPQ#QDCPQ#QECCLKQl机械开关的抖动存在三种情况：按下时有抖动，松开时也有抖动；按下时有抖动，松开时无抖动；按下时无抖动，松开时有抖动。机械开关的抖动波形、抖动次数、抖动时间都是随机的，并不是每次都会产生抖动。 l不同开关的最长抖动时间也不同。抖动时间的长短和机械开关特性有关，一般为5ms到10ms。但是，某些开关的抖动时间长达20ms，甚至更长。所以，在具体设计中要具体分析，根据实际情况
