## What is an edge detection circuit?

An edge detector circuit is a simple circuit with one input and one output. The circuit creates a short pulse when a defined edge, rising, falling, or both depending on the configuration, is detected.

## How do you find fall edge in Verilog?

Design a Verilog module to detect the falling edge of an input signal. The input signal is synchronous to the clock, and when a falling edge is seen, a 1 clock cycle pulse should be emitted as an output signal. Draw your Verilog implementation of this circuit as a schematic of gates and flip-flops.

How do you define a state 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 Posedge in Verilog?

The posedge is the event of changing a value of either a variable or net with a direction toward the value 1. The posedge is detected on the transition from 0 to (x, z, or 1), and from (x or z) to 1. I use it to define either a flip-flop or a flip-flop with an asynchronous reset in a sequential logic.

### What is rising and falling edge?

A rising edge (or positive edge) is the low-to-high transition. A falling edge (or negative edge) is the high-to-low transition.

What is the negative edge detector?

NEG compares the signal state of address 1 with a signal state from the previous scan, which is stored in address 2. If the current RLO state is “1” and the previous state was “0” the RLO bit will be “1” after this instruction.

#### How do you create a pulse in Verilog?

one pulse code in verilog
O/p of the first flip flop goes as input to the second and the output of the second goes as I/p clear to the first, take o/p from the o/p of the first flip flop, this will be a single cycle pulse. Your enable can be any cycle width.

#### How do you find the rising edge of a signal?

Description. The Detect Rise Positive block detects a rising edge by determining if the input is strictly positive, and its previous value was nonpositive. The output is true (equal to 1 ) when the input signal is greater than zero, and the previous value was less than or equal to zero.

How are parameters defined in Verilog?

In Verilog, parameters are constants and do not belong to any other data type such as register or net data types. A constant expression refers to a constant number or previously defined parameter. We cannot modify parameter values at runtime, but we can modify a parameter value using the defparam statement.

## How do you define timescale in Verilog?

In `module timescale_check2`, timescale is 1ns / 1ps. Timescale/Time Precision = 1ns/1ps = 1000 = 103 So 3 digits after decimal will be used. In this case 10.566601 becomes 10567 and 21.546604 becomes 21547. Below examples show simulation results for timescales 100ns/1ns, 1ms / 1us and 10 ms / 10 ns.

## What is the difference between Posedge and Negedge?

Super Moderator. The difference between posedge and negedge reset is in the active reset level, an arbitrary design decision. I presume you are referring to the commonly known design template for an edge triggered FF with asynchronous reset.

What is a positive edge detector?

The idea behind a positive edge detector is to delay the original signal by one clock cycle, take its inverse and perform a logical AND with the original signal. The module shown above is named pos_edge_det and has two inputs and one output. The design aims to detect the positive edge of input sig, and output pe.

### What is the difference between rising edge and falling edge?

rising edge: when the input signal is transitioning from a low state (e.g. 0) to a high state (e.g. 1) falling edge: when the input signal is transitioning from a high state (e.g. 1) to a low state (e.g. 0) either edge: when the input signal is changing state, from high to low or from low to high.

### How a rising edge is detected?

What is positive edge detection?

Positive RLO edge detection:
It detects the rising edge signal change in the address from 0 to 1 and displays it as RLO as 1 after the instruction. The RLO prior to the instruction is stored in the memory address.

#### How do you stretch a signal in Verilog?

How do I stretch a signal in Verilog?

Or use a register to keep the signal high till some condition asserts to true.

1. always@(posedge clk or negedge rst_n)
2. Begin.
3. If(!rst_n)
4. Stretch_cntr <= ‘d0;
5. Else if(stretch_cntr_done)
6. Stretch_cntr <= ‘d0;
7. Else (/*add cond if any*/)
8. Stretch_cntr <= Stretch_cntr + 1’d1;

How do I change duty cycle in Verilog?

EDIT #1 : If you instead want a 60% duty cycle for say an eg. PWM signal, then the following simple Verilog code should work.
Here’s the simple test bench :

1. module pwm_tb;
2. reg CLK;
3. reg RST;
4. wire OUTPUT;
5. integer clkcount;
6. pwm pwm_test1(. CLK(CLK), . RST(RST), . OUTPUT(OUTPUT));
7. initial.
8. begin.

## What is difference between define and parameter?

define is a preprocessor macro and operates via textual substitution, and parameter (or localparam) is a language construct. Much like in software, you should generally prefer to use parameters over defines, since defines can lead to many problems include namespace pollution and accidental substitution.

What are defines in Verilog?

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. A macro can be defined with argument(s).

### What is the difference between == and === in Verilog?

In Verilog: == tests logical equality (tests for 1 and 0, all other will result in x) === tests 4-state logical equality (tests for 1, 0, z and x)

### What does the timescale 1ns 1ps mean in Verilog?

`timescale 1ns/1ps means that all the delays that follow (like# 5.1234) are interpreted to be in nanoseconds and any fractions will be rounded to the nearest picosecond (5123ps). However, all delays are represented as integers. The simulator knows nothing about seconds or nanoseconds, only unit-less integers.

What is always posedge CLK?

always@(posedge CLK) is used to describe a D-Flip Flop, while @(posedge. CLK); is used in testbench. For example, c = d; @(posedge CLK);

#### What is always in Verilog?

In Verilog, the always block is one of the procedural blocks. Statements inside an always block are executed sequentially. An always block always executes, unlike initial blocks that execute only once at the beginning of the simulation. The always block should have a sensitive list or a delay associated with it.