How do you detect a sequence of "1101" arriving serially
from a signal line?
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Answer / amit malik
PS I/P NS O/P
S0 0 S0 0
S0 1 S1 0
S1 0 S0 0
S1 1 S2 0
S2 0 S3 0
S2 1 S2 0
S3 0 S0 0
S3 1 S1 1
| Is This Answer Correct ? | 27 Yes | 0 No |
Answer / virag
Use 4 flip-flops
Tap output from all 4 , connect the second bit to an
inverter and AND all the outputs .
When the output of AND gate is 1. the sequence is detected
| Is This Answer Correct ? | 8 Yes | 3 No |
Answer / govind vijayakumar
Just put a SIPO (Serial In Paralle Out)Network at the
output, followed by a gate network.
4 parallel outputs from the SIPO are taken and the signal
lines whose output is supposed to be one are fed to a 3
input and gate. The 0 output is fed to a not gate and the
output of both the gates are anded together. If this
sequence comes then output will be one, otherwise 0.
| Is This Answer Correct ? | 5 Yes | 5 No |
Answer / guest
PS I/P NS O/P
S0 0 S0 0
S0 1 S1 0
S1 0 S0 0
S1 1 S2 0
S2 0 S3 0
S2 1 S1 0
S3 0 S0 0
S3 1 S1 1
when s2=1 it should go to s1... otherwise it will not detect
the sequence like "...11101..."
| Is This Answer Correct ? | 3 Yes | 3 No |
Answer / genesys
Answer 2 is not correct. It should be :
PS I/P NS O/P
S0 0 S0 0
S0 1 S1 0
S1 0 S0 0
S1 1 S2 0
S2 0 S3 0
S2 1 S0 0
S3 0 S0 0
S3 1 S1 1
where: PS - previous state of the state machine; i/p - input
to the state machine; NS - next state of the state machine;
O/P - output from the state machine
| Is This Answer Correct ? | 8 Yes | 9 No |
Answer / ankush
Sorry, I don't understand the answers here clearly. Can
anyone explain this more clearly
| Is This Answer Correct ? | 1 Yes | 3 No |
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Need to convert this VHDL code into VLSI verilog code? 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;
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