Important Note: This simulation is designed for desktop view only. For the best experience, please use a desktop monitor with a minimum resolution of 1280x720 pixels. The simulation may not function properly on smaller screens like mobile devices or tablets.

1. Understanding the Simulation

This simulation helps you learn about Counter implementation in Verilog:

• Counter Design: A sequential circuit that counts in a particular sequence on each clock cycle.
• The counter increments by 1 at each clock edge (posedge or negedge CLK).
• It demonstrates sequential logic behavior using clocked always blocks.

2. Getting Started

1. Enter your module name and testbench name in the respective fields:
   • Module names must follow Verilog naming conventions.
   • Only letters, numbers, and underscores are allowed (no hyphens or special characters).
   • Testbench name must end with '_tb'.

3. Building the Verilog Module

1. In the first column, arrange the code blocks in the correct order by dragging and dropping them:

   • The code block that defines inputs, outputs, and module name should be placed first
   • Followed by the code block that defines the module functionality
   • Finally, the end of module block

2. Select the appropriate signals:

   • Input: CLK (clock input)
   • Output: Out (counter output)

3. Define the functionality using the always block:

   • Select the condition of always block as 'posedge CLK' or 'negedge CLK' accordingly
   • The counter_up must be incremented by 1 at the chosen clock edge
   • Fill in the LHS and RHS of the assignment keeping in mind what value should be assigned at the clock edge
   • The assignment operator must be '<=' (not '=') because for sequential storage behavior, we always need to select the non-blocking assignment operator (<=)
   • Use the assign statement to assign the value of counter_up to the final output "Out"

4. Creating the Testbench

1. In the second column, arrange the testbench code blocks in the correct order:

   • Testbench name definition
   • Signal declarations (reg for inputs, wire for outputs)
   • Module instantiation
   • Clock wave and input definitions
   • End of module

2. Define the testbench signals:

   • reg CLK; wire Out

3. Connect the ports correctly in the module instantiation:

   • Enter the name of the verilog module you have earlier coded
   • Select the arguments in the same order as you have chosen in the Counter module
   • Ensure proper mapping of CLK input and Out output

5. Validation and Observation

1. Click the "Validate" button to check your code.
2. The observation column will show:
   • Error messages in red if there are mistakes. Refer to the Troubleshooting section below for dealing with the Error messages.
   • A truth table for the CLK wave you have selected if the code is correct.
3. If you need to start over, click the "Reset" button to shuffle the code blocks.

Verilog Syntax Reference

• For detailed Verilog syntax rules, refer to the Verilog Syntax Guide.
• For module and testbench examples, visit ASIC World Verilog Tutorial.

6. Troubleshooting

If you see error messages, carefully check:

• Module and testbench names follow the naming rules.
• Code blocks are in the correct order.
• CLK is properly declared as input and Out as output.
• The always block condition matches your choice (posedge or negedge CLK).
• Non-blocking assignment (<=) is used for sequential logic.
• The assign statement correctly connects counter_up to Out.

Additional tips:

• Use the Reset button to start fresh if needed.
• Observe the fluctuations in input wave and corresponding expected and observed output wave.
• Verify the counter increments correctly on each clock edge.

Important Reminders

• Verilog is case-sensitive.
• All signals must be properly declared before use.
• Testbench signals must match the module ports.
• Code blocks must be in the correct order for the simulation to work.
• Use non-blocking assignment (<=) for sequential logic in always blocks.
• The counter behavior depends on the chosen clock edge (posedge or negedge).