VHDL code for Traffic Light Interface With FPGA

Traffic Light Controller

Traffic light controller consists of 12 Nos. point led arranged by 4Lanes. Each lane has Go (Green), Listen(Yellow) and Stop(Red) LED is being placed. Each LED has provided for current limiting resistor to limit the current flows to the LEDs.

VHDL code for Traffic Light Controller interfacing with Spartan6 FPGA kit

All the 12 LED’s interfaced with Spartan3 FPGA Development Board

through series Resister 330 ohm and another end is terminated to ground.

Schematics to interface Traffic Light Controller with Spartan6 FPGA

Traffic Light Controller Placement in Spartan6 FPGA Development Kit

VHDL Code Description:

The  finite state machine is designed to perform traffic light controller operation by changing state at particular time delay and each state trigger 3 red LED’s on 3 sides and switch from green to yellow and yellow to red each side and each state.

VHDL Code for Traffic Light Controller

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

 

entity traffic_light is

port ( clk : in std_logic;

       rst : in std_logic;

       northgreen : out std_logic;

               northred   : out std_logic;

               northyel   : out std_logic;

               southgreen : out std_logic;

               southred   : out std_logic;

               southyel   : out std_logic;

               eastgreen  : out std_logic;

               eastred    : out std_logic;

               eastyel    : out std_logic;

               westred    : out std_logic;

               westgreen  : out std_logic;

               westyel    : out std_logic);

end traffic_light;

 

architecture Behavioral of traffic_light is

type contol is (north,south,east,west);

signal control,control1 : contol := north;

begin

process(clk,rst)

variable i : integer := 0;

begin

if rst = '1' then

if clk'event and clk = '1' then

if i < 1500000000 then

i := i + 1;

elsif i = 1500000000 then

control <= control1;

i := 0;

end if;

if control = north then

if i >= 0 and i <= 750000000 then

northgreen <= '1';

northred   <= '0';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 750000000 and i <= 1000000000 then

northgreen <= '0';

northred   <= '0';

northyel   <= '1';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 1000000000 and i < 1500000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '1';

eastred    <= '0';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

 

control1 <= east;

end if;

elsif control = east then

 

if i >= 0 and i <= 750000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '1';

eastred    <= '0';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 750000000 and i <= 1000000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '0';

eastyel    <= '1';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 1000000000 and i < 1500000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '1';

southred   <= '0';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

 

 

control1 <= south;

end if;

elsif control = south then

if i >= 0 and i <= 750000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '1';

southred   <= '0';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 750000000 and i <= 1000000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '0';

southyel   <= '1';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

elsif i > 1000000000 and i < 1500000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '0';

westgreen  <= '1';

westyel    <= '0'; 

 

control1 <= west;

end if;

elsif control = west then

 

if i >= 0 and i <= 750000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '0';

westgreen  <= '1';

westyel    <= '0'; 

elsif i > 750000000 and i <= 1000000000 then

northgreen <= '0';

northred   <= '1';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '0';

westgreen  <= '0';

westyel    <= '1'; 

elsif i > 1000000000 and i < 1500000000 then

northgreen <= '1';

northred   <= '0';

northyel   <= '0';

southgreen <= '0';

southred   <= '1';

southyel   <= '0';

eastgreen  <= '0';

eastred    <= '1';

eastyel    <= '0';

westred    <= '1';

westgreen  <= '0';

westyel    <= '0'; 

 

 

control1 <= north;

end if;

end if;

end if;

end if;

end process;

end Behavioral;

User Constraint File

NET "clk"  LOC = "p185"  ;
NET "clk"  LOC = "C9"  ;
NET "eastgreen"  LOC = "H12"  ;
NET "eastred"  LOC = "D14"  ;
NET "eastyel"  LOC = "E13"  ;
NET "northgreen"  LOC = "B16"  ;
NET "northred"  LOC = "A15"  ;
NET "northyel"  LOC = "A16"  ;
NET "rst"  LOC = "G13"  ;
NET "southgreen"  LOC = "G16"  ;
NET "southred"  LOC = "F16"  ;
NET "southyel"  LOC = "F14"  ;
NET "westgreen"  LOC = "B14"  ;
NET "westred"  LOC = "F15"  ;
NET "westyel"  LOC = "C15"  ;