Homework6a_Vending_Machine

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Oct 30, 2023

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Homework-6a : Vending Machine ECE-111 Advanced Digital Design Project Vishal Karna

Homework-6a : Vending Machine ❑ Design FSM for Vending Machine with following mentioned requirements: ▪ Dispatches a pack of candy upon deposit of 15 cents by the customer ▪ Has single coin slot and only accepts nickels and dimes. Doesn’t take pennies or quarters ▪ Does not provide any change back to the customer in case more than 15 cents are deposited ▪ Once candy is dispatched, vending machine should move to reset state 2 Vending Machine FSM N open clk rstn Coin Sensor D Candy Release Mechanism Vending Machine Moore State Transition Diagram CENTS_0 OPEN = 0 CENTS_5 OPEN= 0 CENTS_10 OPEN = 0 (N=0 & D=0) || rstn=0 N=1 D=1 D=1 CENTS_15 OPEN = 1 N=1 N=1 or D=1 rstn=1 rstn=0 N=0 & D=0 N=0 & D=0 This Vending machine requires manual reset to go back to CENTS_0 state after candy is dispatched. Hence rstn=0 is required for FSM to transition from CENTS_15 to CENTS_0

Homework-6a : Vending Machine ❑ Vending Machine FSM supports Manual Reset, however FSM with Auto Reset can also be implemented ▪ Manual Reset FSM : Requires reset to be asserted (rstn = 0) for FSM to go back to CENTS_0 state from CENTS_15 state once candy is dispatched ▪ Auto Reset FSM : Without reset (rstn = 0), FSM transitions from CENTS_15 to CENTS_0 3 With Manual Reset N=0 & D=0 N=0 & D=0 Students can implement FSM with Manual reset or Auto Reset. Auto Reset means that After entering CENTS_15 state, FSM will transition unconditionally without any reset, to CENTA_0 state With Auto Reset (Alternate Implementation) CENTS_0 OPEN = 0 CENTS_5 OPEN= 0 CENTS_10 OPEN = 0 (N=0 & D=0) || rstn=0 N=1 D=1 D=1 CENTS_15 OPEN = 1 N=1 N=1 or D=1 N=0 & D=0 N=0 & D=0 This Vending machine requires manual reset to go back to CENTS_0 state after candy is dispatched. Hence rstn=0 is required for FSM to transition from CENTS_15 to CENTS_0 CENTS_0 OPEN = 0 CENTS_5 OPEN= 0 CENTS_10 OPEN = 0 (N=0 & D=0) || rstn=0 N=1 D=1 D=1 CENTS_15 OPEN = 1 N=1 N=1 or D=1 rstn=1 rstn=0

Homework-6a : Vending Machine ❑ In mealy FSM register input's N and D if output "open" gets asserted to '1' before depositing 15 Cents (register means add flipflop) ▪ When implementing mealy FSM for Vending Machine, add a flipflop at the input of 'N' and 'D' ▪ And these registered 'r_N' and 'r_D' should be used in always_comb next state logic procedural blocks 4 Without Registering N and D, See Potential Waveform Snapshot Below with pre-mature open = 1

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