Explain ASIC Design Flow?
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Answer Posted / david schkolnik
To Answer #1 I must add the check done between steps:
After:
architecture is defined: Review with peers:
RTL coding: Logic simulation with tools like NCsim
Synthesis: first shot STA of (with estimated delays).
Formal verification against RTL (w/Formality)
DFT insertion and ATPG: Logic simulation, coverage, - Formal verification against
pre-DFT netlist.
Place and Route: sign-off STA (with actual delays)
LVS, DRC
Because the Verification process of the original code continues in parallel during the rest of the project, some bugs come up very late when it's too late to re-do the whole thing. Sometimes timing problems need late fixes. These small changes are called ECO, which are made straight on Layout. Then LVS needs to be run again and the result be analyzed by the top engineers in the team. Still, many bugs are born in this stage.
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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;
