This document summarizes a lecture on finite state machines: 1. The lecture discusses finite state machines, including examples, state diagrams, state tables, and implementing FSMs in Verilog. 2. As an example, the lecture examines a circuit to store 16 bits of information and check if four 4-bit numbers are equal. 3. The problem set asks students to build Verilog systems for state machines, including one to control an elevator based on floor and button input.

1. ECE 287 – Lecture 15
Finite State Machines - II

2. Announcements
• Next Quiz on Wednesday
• Exam II – Nov 15th

7. FSM Example
For the given circuit, we want to use it to
store 16 bits of information and check if all
the 4 bit individual numbers (4 of them) are
all equal.
input
valid
clk
out

8. Algorithm

9. State Diagram

10. State Table

11. State Machine Circuit

12. What if clock is fast?
How does the system start up?

13. Actual Comparison Circuit

14. Verilog for FSMs
reset
In = 0
In = 0
B
A
Out = 1
Out = 0
In = 1
In = 1

15. Try and build the Verilog for bit
matching example at the start of class…

16. Problem Set
1. Build a verilog system for:
In = 0
In = 1
In = 0
B
Out = 1
A
Out = 0
In = 0
In = 1
G
Out = 1
In = 1

17. Problem Set
1. Build a verilog system for:
•
Design a state machine controller for an elevator. The elevator can be at one of two
floors: Ground or First. There is one button that controls the elevator, and it has two
values: Up or Down. Also, there are two lights in the elevator that indicate the current
floor: Red for Ground, and Green for First. At each time step (clock), the controller
checks the current floor and current input, changes floors and lights in the obvious way.