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关键词
交通信号系统、VHDL语言、ispLEVER、Lattice、ispLSI1032E
题目要求
1． 路型：十字交叉
2． 相变周期：30s
3． 绿闪时间：5s
4． 黄灯时间：2s
5． 绿信比：1:2
6． 定时输入：256Hz TTL
7． 两位数码倒计时
8． 强制放行按钮：东西、南北方向（任意按钮解除）
摘要
本设计的红绿交通灯信号系统为模拟实际的十字路口交通信号灯。故外部硬件电路方面包括：两组红绿灯、两组七段显示器、一组手动与自动控制开关。软件方面：将红绿灯交通信号系统划分成若干个子电路，赋予VHDL程序代码实现，将各个小电路相连接。交通灯系统可以调整红绿灯电路的强制通行和复位，以增加灵活性。
一、设计状态转移图及软件模块图
1、绘制软件模块图
2、利用状态机绘制状态转移图
二、交通信号系统VHDL模块
该系统由四个子电路构成（如图）：
（1） clk_gen 时钟脉冲发生电路（即分频电路）
（2） count_down 倒计时控制电路
（3） traffic_mux 计数秒数选择电路
（4） traffic_fsm 红绿信号灯控制电路
1、 clk_gen 时钟脉冲发生电路
在红绿交通信号系统中，大多数的情况是通过自动控制的方式指挥交通的。此，为了避免意外事件的发牛，电路必须给一个稳定的时钟才能让系统正常运作。但为了配合高峰时段，防止交通拥挤。有时也必须使用手动控制，即让交警能够顺利指挥交通。clk_gen电路路最主要的功能就是产生—些额外的输出信号，井将其用做后续几个电路的使能控制与同步信号处理。
clk_gen时钟脉冲发生电路VHDL程序：
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity clk_gen is
port( reset: in std_logic;
clk: in std_logic;
ena_two: in std_logic;
ena_scan: out std_logic;
ena_1hz: out std_logic;
flash_1hz: out std_logic);
end;
architecture behavior of clk_gen is
constant scan_bit: positive :=2;
constant scan_val: positive :=4;
constant two_hz_bit: positive :=7;
constant two_hz_val: positive :=125;
signal clk_scan_ff: std_logic_vector(scan_bit-1 downto 0);
signal clk_2hz_ff: std_logic_vector(two_hz_bit-1 downto 0);
signal ena_s: std_logic;
signal ena_one: std_logic;
signal ena_two: std_logic;
begin
scan:process(reset,clk)
begin
if reset='1' then
clk_scan_ff<="00";
ena_s<='0';
elsif (clk'event and clk='1') then
if clk_scan_ff>=scan_val-1 then
clk_scan_ff<="00";
ena_s<='1';
else
clk_scan_ff<=clk_scan_ff+1;
ena_s<='0';
end if;
end if;
end process;
ena_scan<=ena_s;
two_hz:process(reset,clk,ena_s)
begin
if reset='1' then
ena_one<='0';
ena_two<='0';
clk_2hz_ff<="0000000";
elsif (clk'event and clk='1') then
if ena_s='1' then
if clk_2hz_ff>=two_hz_val-1 then
clk_2hz_ff<="0000000";
ena_two<='1';
ena_one<=not ena_one;
else
clk_2hz_ff<=clk_2hz_ff+1;
ena_two<='0';
ena_one<=ena_one;
end if;
end if;
end if;
end process;
ena_1hz<=ena_one and ena_two and ena_s;
flash_1hz<=ena_one;
end behavior;
模块波形仿真：
2、count_down 倒计时控制电路
当过马路的时候，绿灯的一方有时会附加—个显示器告诉行人，日前还剩下几秒信号灯将变红。因此，count_down 电路最主要的功能就是负责接收traffic_mux电路输出的倒计时秒数值，然后将其转换成BCD码，利用七显示管显示．让行人能清楚知道再过多久就会变成红灯。
count_down 倒计时控制电路VHDL程序：
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity count_down is
port( reset: in std_logic;
clk: in std_logic;
ena_1hz: in std_logic;
recount: in std_logic;
load: in std_logic_vector(7 downto 0);
seg7: out std_logic_vector(15 downto 0);
next_state: out std_logic);
end;
architecture count_down of count_down is
signal cnt_ff: std_logic_vector(7 downto 0);
begin
count:process(clk,reset)
begin
if (reset='1') then
cnt_ff<="00000000";
seg7<="0000000000000000";
elsif (clk'event and clk='1') then
if ena_1hz='1' then
if (recount='1') then
cnt_ff<=load-1;
else
cnt_ff<=cnt_ff-1;
end if;
end if;
case conv_integer(cnt_ff) is
when 0=>seg7(15 downto 0)<="0011111100111111";
when 1=>seg7(15 downto 0)<="0011111100000110";
when 2=>seg7(15 downto 0)<="0011111101011011";
when 3=>seg7(15 downto 0)<="0011111101001111";
when 4=>seg7(15 downto 0)<="0011111101100110";
when 5=>seg7(15 downto 0)<="0011111101101101";
when 6=>seg7(15 downto 0)<="0011111101111101";
when 7=>seg7(15 downto 0)<="0011111100000111";
when 8=>seg7(15 downto 0)<="0011111101111111";
when 9=>seg7(15 downto 0)<="0011111101111011";
when 10=>seg7(15 downto 0)<="0000011000111111";
when 11=>seg7(15 downto 0)<="0000011001011011";
when 12=>seg7(15 downto 0)<="0000011001011011";
when 13=>seg7(15 downto 0)<="0000011001001111";
when 14=>seg7(15 downto 0)<="0000011001100110";
when 15=>seg7(15 downto 0)<="0000011001101101";
when 16=>seg7(15 downto 0)<="0000011001111101";
when 17=>seg7(15 downto 0)<="0000011000000111";
when 18=>seg7(15 downto 0)<="0000011001111111";
when 19=>seg7(15 downto 0)<="0000011001111011";
when 20=>seg7(15 downto 0)<="0101101100111111";
when 21=>seg7(15 downto 0)<="0101101100000110";
when 22=>seg7(15 downto 0)<="0101101101011011";
when 23=>seg7(15 downto 0)<="0101101101001111";
when 24=>seg7(15 downto 0)<="0101101101100110";
when 25=>seg7(15 downto 0)<="0101101101101101";
when 26=>seg7(15 downto 0)<="0101101101111101";
when 27=>seg7(15 downto 0)<="0101101100000111";
when 28=>seg7(15 downto 0)<="0101101101111111";
when 29=>seg7(15 downto 0)<="0101101101111011";
when others=>seg7(15 downto 0)<="0011111100111111";
end case;
end if;
end process;
next_state<='1' when cnt_ff=1 else '0';
end count_down;
模块波形仿真：
3、traffic_mux 计数秒数选择电路
traffic_mux电路最主要的功能就是负责输出显示器需要的倒数秒数值，作为倒数显示器电路的计数秒数。
traffic_mux 计数秒数选择电路VHDL程序：
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity traffic_mux is
port( reset: in std_logic;
clk: in std_logic;
ena_scan: in std_logic;
recount: in std_logic;
sign_state: in std_logic_vector(1 downto 0);
load: out std_logic_vector(7 downto 0));
end;
–define the signal_structure and flow of the device
architecture behavior of traffic_mux is
constant yellow0_time: integer:=5;
constant green0_time: integer:=20;
constant yellow1_time: integer:=5;
constant green1_time: integer:=20;
begin
–to generate a value of counter by load
load_time:process(reset,clk)
begin
if reset='1' then
load<="00000000";
elsif (clk'event and clk='1') then
if (ena_scan='1' and recount='1') then
case sign_state is
when "00"=>
load<=conv_std_logic_vector(green1_time,8);
when "01"=>
load<=conv_std_logic_vector(yellow0_time,8);
when "10"=>
load<=conv_std_logic_vector(green0_time,8);
when others=>
load<=conv_std_logic_vector(yellow1_time,8);
end case;
end if;
end if;
end process;
end behavior;
模块波形仿真：
4、traffic_fsm 红绿信号灯控制电路
在红绿灯交通系统中，大多数的情况是通过自动控制的方式指挥交通的。但为了配合高峰时段，防止交通拥挤，有时还必须使用手动控制，即交警自行指挥交通。因此，traffic_fsm电路除了负责监控路口红绿灯之外，主要的功能就是能够利用开关来切换手动与自动的模式，让交警能够通过外部输入的方式来控制红绿灯交通型号系统的运作。
假如是由于电器效应引起开关误动作，开关抖动的速度是非常快的，故电路可能会产生误动作，本程序的debounce段代码就是为了达到这种抖动消除装置的目的。
traffic_fsm 红绿信号灯控制电路VHDL程序：
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity traffic_fsm is
port( reset: in std_logic;
clk: in std_logic;
ena_scan: in std_logic;
ena_1hz: in std_logic;
flash_1hz: in std_logic;
a_m: in std_logic;
st_butt: in std_logic;
next_state: in std_logic;
recount: out std_logic;
sign_state: out std_logic_vector(1 downto 0);
red: out std_logic_vector(1 downto 0);
green: out std_logic_vector(1 downto 0);
yellow: out std_logic_vector(1 downto 0));
end;
architecture traffic_fsm of traffic_fsm is
type sreg0_type is (r0g1, r0y1, g0r1, y0r1, y0y1, y0g1, g0y1, r0r1);
signal state: sreg0_type;
signal st_transfer: std_logic;
signal light: std_logic_vector(5 downto 0);
begin
debounce:process (reset,clk,ena_scan,st_butt)
variable rebn_ff: std_logic_vector(5 downto 0);
begin
if (st_butt='1' or reset='1') then
rebn_ff:="111111";
st_transfer<='0';
elsif (clk'event and clk='1') then
if (ena_scan='1') then
if (rebn_ff>=3) then
rebn_ff:=rebn_ff-1;
st_transfer<='0';
elsif (rebn_ff=2) then
rebn_ff:=rebn_ff-1;
st_transfer<='1';
else
rebn_ff:=rebn_ff;
st_transfer<='0';
end if;
end if;
end if;
end process;
fsm:process (clk,ena_1hz,reset)
begin
if(reset='1') then
state<=r0g1;
sign_state<="01";
recount<='1';
else
if (clk'event and clk='1') then
case state is
when r0g1 =>
if (a_m='1' and ena_1hz='1') then
if (next_state='1') then
recount<='1';
state<=r0y1;
sign_state<="01";
else
recount<='0';
state<=r0g1;
end if;
elsif (a_m='0' and ena_scan='1') then
if (st_transfer='0') then
recount<='1';
state<=r0g1;
else
recount<='1';
state<=r0y1;
sign_state<="01";
end if;
end if;
when r0y1 =>
if (a_m='1' and ena_1hz='1') then
if (next_state='1') then
recount<='1';
state<=g0r1;
sign_state<="10";
else
recount<='0';
state<=r0y1;
end if;
elsif (a_m='0' and ena_scan='1') then
if (st_transfer='0') then
recount<='1';
state<=r0y1;
else
recount<='1';
state<=g0r1;
sign_state<="10";
end if;
end if;
when g0r1 =>
if (a_m='1' and ena_1hz='1') then
if (next_state='1') then
recount<='1';
state<=y0r1;
sign_state<="11";
else
recount<='0';
state<=g0r1;
end if;
elsif (a_m='0' and ena_scan='1') then
if (st_transfer='0') then
state<=g0r1;
else
recount<='1';
state<=y0r1;
sign_state<="11";
end if;
end if;
when y0r1 =>
if (a_m='1' and ena_1hz='1') then
if (next_state='1') then
recount<='1';
state<=y0g1;
sign_state<="00";
else
recount<='0';
state<=y0r1;
end if;
elsif (a_m='0' and ena_scan='1') then
if (st_transfer='0') then
recount<='1';
state<=y0r1;
else
recount<='1';
state<=r0r1;
sign_state<="00";
end if;
end if;
when others =>
state<=r0g1;
recount<='0';
sign_state<="00";
end case;
end if;
end if;
end process;
light<="010010" when (state=r0g1) else
"011000" when (state=r0y1) else
"100001" when (state=r0y1) else
"100100" when (state=r0y1) else
"110000";
red<=light(5 downto 4);
yellow<=light(3 downto 2) and (flash_1hz & flash_1hz);
green<=light(1 downto 0);
end traffic_fsm;
配合完整模块仿真：
三、完整软件波形仿真结果
1、clk_gen 时钟脉冲发生电路（即分频电路）
2、count_down 倒计时控制电路
3、traffic_mux 计数秒数选择电路
4、traffic_fsm 红绿信号灯控制电路
四、ispLS1032E芯片引脚图
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