How are simulation and synthesis used in Verilog?

How are simulation and synthesis used in Verilog?

Figure 3.1 Simulation in Verilog The output of synthesis is a netlist of components of the target library. Often synthesis tools have an option to generate this netlist in Verilog. In this case, the same testbench prepared for pre-synthesis simulation can be used with the netlist generated by the synthesis tool.

What causes a mismatch between simulation and synthesis?

During Verilog simulation, when binary pattern 2’b11 is driven onto the select lines, the y-output will behave as if it was latched , but the synthesis will treat the y-output as a “don’t care” for the same select-line combination because of the full_case directive, causing a functional mismatch to occur between simulation and synthesis.

How is X assignment interpreted in Verilog simulator?

The‘X’ assignment is interpreted as an unknown by the Verilog simulator (with the exception of casex), but is interpreted as a “don’t care” by synthesis tools. Making ‘X’ assignments can cause mismatches between pre- and post-synthesis simulations.

Why do I avoid the # syntax in Verilog?

This is one reason why I avoid the “#” syntax in Verilog, such as a <= #2 b;. Just because you tell the Verilog simulator that something will happen “2.5ns” later, doesn’t mean it will achieve that “2.5ns” result in hardware.

How to force a signal to certain value from Verilog?

“assign” is for wire type. We evaluate reg in “initial” in the testbench. Click to expand… There is also a “procedural assign” in Verilog – less used though. Forcing internal signals in design is not a good testbench writing practice. Try to minimize this as much as possible. This limits testbench reusability.

What is the Verilog code for DUT testbench?

Figure 4.2:Verilog code for a DUT/testbench simulation environment (Copyright c 2005, 2010, Cadence Design Systems, Inc. All rights reserved worldwide. Reprinted with permission.)

Is it good to force internal signals in design?

Forcing internal signals in design is not a good testbench writing practice. Try to minimize this as much as possible. This limits testbench reusability. rtl you want the same testbench for netlist.

Which is the best free implementation of Verilog?

Welcome to the home page for Icarus Verilog. This is the source for your favorite free implementation of Verilog! What Is Icarus Verilog? Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format.

Are there any free or open source synthesis tools?

Are there any free or open source synthesis tools available that can convert Verilog RTL into a generic gate netlist? (composed of generic NAND, NOR, XOR, D-flops/registers, etc. Optimization not required.). If not for the full language, how about for a “useful” subset of RTL (beyond merely a Verilog gate level netlist)?

Which is the best Verilog simulator for OSS?

Icarus Verilog, OSS tool, very handy, even has a simulator. http://iverilog.icarus.com/ Its a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code written in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate an intermediate form called vvp assembly.