Answer Posted / rahul singhal
-----By RAHUL SINGHAL----
----This is the code of a FSM that implements a toll booth -
----controller
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL; ----using all functions of
specific package---
ENTITY tollbooth2 IS
PORT (Clock,car_s,RE : IN STD_LOGIC;
coin_s : IN STD_LOGIC_VECTOR(1 DOWNTO 0);
r_light,g_light,alarm : OUT STD_LOGIC);
END tollbooth2;
ARCHITECTURE Behav OF tollbooth2 IS
TYPE state_type IS
(NO_CAR,GOTZERO,GOTFIV,GOTTEN,GOTFIF,GOTTWEN,CAR_PAID,CHEATE
D);
------GOTZERO = PAID $0.00---------
------GOTFIV = PAID $0.05----------
------GOTTEN = PAID $0.10----------
------GOTFIF = PAID $0.15----------
------GOTTWEN = PAID $0.20---------
SIGNAL present_state,next_state : state_type;
BEGIN
-----Next state is identified using present state,car &
coin sensors------
PROCESS(present_state,car_s,coin_s)
BEGIN
CASE present_state IS
WHEN NO_CAR =>
IF (car_s = '1') THEN
next_state <= GOTZERO;
ELSE
next_state <= NO_CAR;
END IF;
WHEN GOTZERO =>
IF (car_s ='0') THEN
next_state <= CHEATED;
ELSIF (coin_s = "00") THEN
next_state <= GOTZERO;
ELSIF (coin_s = "01") THEN
next_state <= GOTFIV;
ELSIF (coin_s ="10") THEN
next_state <= GOTTEN;
END IF;
WHEN GOTFIV=>
IF (car_s ='0') THEN
next_state <= CHEATED;
ELSIF (coin_s = "00") THEN
next_state <= GOTFIV;
ELSIF (coin_s = "01") THEN
next_state <= GOTTEN;
ELSIF (coin_s <= "10") THEN
next_state <= GOTFIV;
END IF;
WHEN GOTTEN =>
IF (car_s ='0') THEN
next_state <= CHEATED;
ELSIF (coin_s ="00") THEN
next_state <= GOTTEN;
ELSIF (coin_s="01") THEN
next_state <= GOTFIV;
ELSIF (coin_s="10") THEN
next_state <= GOTTWEN;
END IF;
WHEN GOTFIF =>
IF (car_s ='0') THEN
next_state <= CHEATED;
ELSIF (coin_s = "00") THEN
next_state <= GOTFIF;
ELSIF (coin_s ="01") THEN
next_state <= GOTTWEN;
ELSIF (coin_s = "10") THEN
next_state <= GOTTWEN;
END IF;
WHEN GOTTWEN =>
next_state <= CAR_PAID;
WHEN CAR_PAID =>
IF (car_s = '0') THEN
next_state <= NO_CAR;
ELSE
next_state<= CAR_PAID;
END IF;
WHEN CHEATED =>
IF (car_s = '1') THEN
next_state <= GOTZERO;
ELSE
next_state <= CHEATED;
END IF;
END CASE;
END PROCESS;-----End of Process 1
-------PROCESS 2 for STATE REGISTER CLOCKING--------
PROCESS(Clock,RE)
BEGIN
IF RE = '1' THEN
present_state <= GOTZERO;
----When the clock changes from low to high,the state of
the system
----stored in next_state becomes the present state-----
ELSIF Clock'EVENT AND Clock ='1' THEN
present_state <= next_state;
END IF;
END PROCESS;-----End of Process 2-------
---------------------------------------------------------
-----Conditional signal assignment statements----------
r_light <= '0' WHEN present_state = CAR_PAID ELSE '1';
g_light <= '1' WHEN present_state = CAR_PAID ELSE '0';
alarm <= '1' WHEN present_state = CHEATED ELSE '0';
END Behav;
| Is This Answer Correct ? | 7 Yes | 0 No |
Post New Answer View All Answers
How clock signal is generated in 8086?
How much total external data memory that can be interfaced to the 8051?
Define bit?
Explain the different types of data transfers possible in the 8085.
What is the maximum supported clock speed of the 8086?
What is the width of address bus?
what is the undefined bits in flag registers of 8085 microprocessor?
List some 8051 microcontroller applications in embedded systems ?
List out the features of 8051 microcontroller?
What does tasm stand for and what is its use?
Which is the tool used to connect the user and the computer?
Define what the sop does with the help of an example.
How many types memory mgt can divided?
What happens when call instruction is executed?
Which interrupt in the 8086 has the highest priority?
