Modulo-N counter in Verilog - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Modulo-N counter in Verilog?

A Modulo-N counter is a digital counter that counts from 0 up to N-1 and then resets back to 0, repeating this cycle continuously.

beginner

How do you reset a Modulo-N counter in Verilog?

You use a reset signal (usually asynchronous or synchronous) that sets the counter value back to 0 when activated.

beginner

Explain the role of the modulus value N in a Modulo-N counter.

The modulus value N defines the number of unique states the counter cycles through before restarting at zero. The counter counts from 0 to N-1.

beginner

What happens when the counter reaches N-1 in a Modulo-N counter?

When the counter reaches N-1, on the next clock pulse it resets to 0 and starts counting again.

intermediate

Write a simple Verilog snippet to implement a Modulo-4 counter with synchronous reset.

module mod4_counter( input clk, input reset, output reg [1:0] count ); always @(posedge clk) begin if (reset) count <= 0; else if (count == 3) count <= 0; else count <= count + 1; end endmodule

What does a Modulo-N counter do when it reaches its maximum count?

A Counts backwards

B Stops counting

C Resets to zero and continues counting

D Freezes at maximum count

A Modulo-N counter resets to zero after reaching its maximum count (N-1) and continues counting from there.

In Verilog, which keyword is used to describe behavior that happens on a clock edge?

A initial

B always @(posedge clk)

C assign

D module

The 'always @(posedge clk)' block describes behavior triggered on the rising edge of the clock signal.

If a Modulo-8 counter counts from 0, what is the highest value it reaches before resetting?

A 7

B 8

C 0

D 1

A Modulo-8 counter counts from 0 up to 7 (which is 8-1) before resetting to 0.

What type of reset sets the counter value back to zero immediately, regardless of the clock?

A Soft reset

B Synchronous reset

C Manual reset

D Asynchronous reset

An asynchronous reset sets the counter to zero immediately, without waiting for a clock edge.

Which Verilog data type is commonly used to store the count value in a Modulo-N counter?

A reg

B wire

C integer

D parameter

The 'reg' type is used to store values that change inside always blocks, such as the count in a counter.

Describe how a Modulo-N counter works and how you would implement it in Verilog.

Think about counting steps and when to reset.

Explain the difference between synchronous and asynchronous reset in a Modulo-N counter.

Consider when the reset affects the counter value.