How do you code a state machine in Verilog?

How do you code a state machine in Verilog?

How to Code a State Machine in Verilog

1. Stepper motor controller state diagram.
2. This block of code creates the state variables.
3. This block of code creates the state registers that hold the next_state and present_state variables.
4. This is the first chunk of the state logic.
5. This is the second chunk of the next state logic.

What is finite state machine in Verilog?

Finite State Machines (FSM) are sequential circuit used in many digital systems to control the behavior of systems and dataflow paths. Examples of FSM include control units and sequencers. This lab introduces the concept of two types of FSMs, Mealy and Moore, and the modeling styles to develop such machines.

How do you write a sequence detector in Verilog?

Here below verilog code for 6-Bit Sequence Detector “101101” is given. This code is implemented using FSM. FSM for this Sequence Detector is given in this image. In this Sequence Detector, it will detect “101101” and it will give output as ‘1’.

How do you declare a parameter in Verilog?

In the new ANSI style of Verilog port declaration, we may declare parameters such as:

1. module design_ip.
2. #(parameter BUS_WIDTH=32,
3. parameter DATA_WIDTH=64)
4. (input [BUS_WIDTH-1:0] addr,
5. // other port declarations.
6. );

How do you define a state in Verilog?

A state machine is a sequential circuit that advances through a number of states. By default, the Quartus II software automatically infers state machines in your Verilog HDL code by finding variables whose functionality can be replaced by a state machine without changing the simulated behavior of your design.

How do I write FSM Code?

Depending on the need, we can choose the type of state machine. In general, or you can say most of the time, we end up using Mealy FSM. Binary encoding : each state is represented in binary code (i.e. 000, 001, 010….) Gray encoding : each state is represented in gray code (i.e. 000, 001, 011,…)

What is sequence detector in FSM?

A sequence detector is a sequential state machine that takes an input string of bits and generates an output 1 whenever the target sequence has been detected. In a Mealy machine, output depends on the present state and the external input (x). Sequence detector is of two types: Overlapping.

What are parameters in System Verilog?

Parameters are Verilog constructs that allow a module to be reused with a different specification. For example, a 4-bit adder can be parameterized to accept a value for the number of bits and new parameter values can be passed in during module instantiation.

How do you define a macro in Verilog?

The term ‘macro’ refers to the substitution of a line or a few lines of text code. The directive “`define” creates a macro for substitution code. Once the macro is defined, it can be used anywhere in a compilation unit scope, wherever required. It can be called by (`) character followed by the macro name.

How to design finite state machines using Verilog?

Designing Finite State Machines (FSM) using Verilog. By Harsha Perla. Designing a synchronous finite state machine (FSM) is a common task for a digital logic engineer. A finite state machine can be divided in to two types: Moore and Mealy state machines.

What happens after state 11 in Verilog FSM?

After state 11, goes to 10 state or 01 depending on the inp, since overlapping pair should not be considered. That is, if 111 comes, it should consider only one pair. Following code the Verilog implementation of the state machine.

How are flip flops used in a FSM?

Common classifications used to describe the state encoding of an FSM are Binary (or highly encoded) and Onehot. A binary-encoded FSM design only requires as many flip-flops as are needed to uniquely encode the number of states in the state machine.

What kind of logic is used in FSM?

Introduction. Basically a FSM consists of combinational, sequential and output logic. Combinational logic is used to decide the next state of the FSM, sequential logic is used to store the current state of the FSM. The output logic is a mixture of both combo and seq logic as shown in the figure below.