What Is The Difference Between The Clocking Block And Modport?

What is skew in digital circuits?

Clock skew (sometimes called timing skew) is a phenomenon in synchronous digital circuit systems (such as computer systems) in which the same sourced clock signal arrives at different components at different times.

The instantaneous difference between the readings of any two clocks is called their skew..

Can we declare an interface as final?

An interface is a pure abstract class. Hence, all methods in an interface are abtract , and must be implemented in the child classes. So, by extension, none of them can be declared as final . Why Interface methods cannot be “static” & “final”?

Why do we use interfaces?

It is used to achieve total abstraction. Since java does not support multiple inheritance in case of class, but by using interface it can achieve multiple inheritance . It is also used to achieve loose coupling. Interfaces are used to implement abstraction.

What is the Race condition in Verilog when it will occur and how do you solve it?

A Verilog race condition occurs when two or more statements that are scheduled to execute in the same simulation time-step, would give different results when the order of statement execution is changed, as permitted by the IEEE Verilog Standard.

How do you create a clock in System Verilog?

There are many ways two generate a clock either by using forever or always. Since the question is for always block I will show some example regarding the same: module clk1();…There could be one more way:module clk1();parameter clk_period = 10;reg clk;initial.begin.clk = 0;end.always #(clk_period/2)More items…

What is virtual interface in UVM?

A virtual interface is a variable that represents an interface instance. The virtual interface must be initialized before using it. i.e, Virtual interface must be connected/pointed to the actual interface. Accessing the uninitialized virtual interface result in a run-time fatal error.

What is virtual function in SystemVerilog?

In SystemVerilog this is called an abstract class and is declared by using the word virtual: … Methods, too, may be declared virtual. This means that if the method is overridden in a derived class, the signature (the return type, the number and types of its arguments) must be the same as that of the virtual method.

How do clocking blocks avoid race conditions?

The same signal is driven and sampled at the same time. => To avoid this race condition, a clocking block in interface is used as it provides an input and output skews to sample and drive, respectively. 2. Race condition between testbench and design.

What is virtual interface in SV?

A virtual interface is a pointer to an actual interface in SystemVerilog. It is most often used in classes to provide a connection point to allow classes to access the signals in the interface through the virtual interface pointer.

Can we write SystemVerilog assertions in class?

Abstract— Complex protocol checks in Universal Verification Methodology Verification Components are often implemented using SystemVerilog Assertions; however, concurrent assertions are not allowed in SystemVerilog classes, so these assertions must be implemented in the only non-class based “object” available, the …

What is program block SystemVerilog?

module in verilog is used for describing hardware, it can contain, always, intial and assign statments. To have clear sepration between testbench and design, SystemVerilog introduces program, which contains full enviroment for testbench. A Program serves following purpose.

Why do we need virtual interface?

Virtual interfaces provide a mechanism for separating abstract models and test programs from the actual signals that make up the design. A virtual interface allows the same subprogram to operate on different portions of a design and to dynamically control the set of signals associated with the subprogram.

What is Uvm_config_db?

UVM Configuration Database. Intro. The uvm_config_db class provides a convenience interface on top of the uvm_resource_db to simplify the basic interface that is used for configuring uvm_component instances. uvm_config_db. All of the functions in uvm_config_db#(T) are static, so they must be called using the :: …

Why do we need clocking blocks?

A clocking block is a set of signals synchronised on a particular clock. It basically separates the time related details from the structural, functional and procedural elements of a testbench. It helps the designer develop testbenches in terms of transactions and cycles.

Why always blocks are not allowed in the program block?

When the last initial block completes, simulation implicitly ends just as if you had executed $finish. If you had an always block, it would never stop, so you would have to explicitly call $exit to signal that the program block completed. This is the reason why we can not have always block inside program.

What is the difference between logic and bit in SystemVerilog?

Datatype “bit” is a two-state datatype, which essentially means it supports only ‘0’ or ‘1’, while datatype “logic” is a four-state datatype, which has the support for ‘0’, ‘1’, ‘x’ (unknown), ‘z’ (high-impedance) as well. What is the use of assertions in SystemVerilog?

What is a static variable in SV?

Static Variables. When a variable inside a class is declared as static , that variable will be the only copy in all class instances. … On the other hand, the normal counter variable ctr is not declared as static and hence every class object will have its own copy.

What are the different types of verification approaches in SV?

Function verification approaches can be divided into two categories. Bottom-up and flat approaches. Bottom-up approach can be done at 4 levels. In unit level verification, a module is verified in its own test environment to prove that the logic, control, and data paths are functionally correct.

What is Modport?

Modports in SystemVerilog are used to restrict interface access within a interface. The keyword modport indicates that the directions are declared as if inside the module. Modports can have. input : Ports that need to be input.

What is the input skew and output skew in the clocking block?

#0 skew for the input signals means that the signals are sampled at the same time as the clocking event, but in the Observed region. #0 skew for the output signals means that they are driven at the same time as the clocking event, in the NBA region.

WHAT IS interface and advantages over the normal way?

Advantages of the interface over the traditional connection, allows the number of signals to be grouped together and represented as a single port, the single port handle is passed instead of multiple signal/ports. interface declaration is made once and the handle is passed across the modules/components.