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
What is internal structure of 8086?
What are software interrupts?
Why do you use two ground pins in microprocessor 8086?
What is lookup table microcontroller?
What is 8255?
What are the software instructions related to stack operations?
Explain db?
What is the maximum supported clock speed of the 8086?
Explain the flag register in the 8085 microprocessor?
How can interrupts be classified in the 8086?
How many i/o ports can 8085 access?
The address capability of 8085 is 64 kb.explain?
Discuss 3 states signals io/m,s0,s1?
Can you name the different types of processor?
What is the purpose of segment register?