CodiodeCodiode
Home
Problem Solving
Skill Tracks
My Assignments
Contests
Leaderboard
Community
Settings
Codiode/Problems/Sequential Logic

Analyze: Simulation Delta Cycles

HardLogic CircuitAnalyze

Hardware simulators use an event-driven execution model where zero-delay events are separated into microscopic time steps called delta cycles.

The code below models a cross-coupled register pair with combinational feedback.

wire d1 = ~q2;
wire d2 = ~q1;

always @(posedge clk) q1 <= d1;
always @(posedge clk) q2 <= d2;

At time T=0, q1 is 0 and q2 is 1. The first rising edge of clk occurs at T=10.

Trace the simulation event queue at T=10. Determine the exact sequence of evaluation, scheduling, and updates across the Active and Nonblocking Assignment (NBA) regions.

Constraints

  • Assume a standard IEEE 1364 Verilog event queue.
  • The clk transition is the only external event at T=10.
  • Continuous assignments execute in the Active region.
  • Delta cycles are zero-delay steps that occur within the same simulation time step.

Topics

VerilogNonblockingDelta CyclesBlockingEvent Queue

Solve this problem

Place the gates, wire them up and watch the signals settle. Every submission runs on the same simulation engine that grades it.

This problem is part of Codiode Pro. The statement above is free to read.

Sign in to solveSee what Pro unlocks

The circuit builder and code editor need a desktop screen. On a phone, read the problem here and open it on a laptop to solve.

Related problems

  • 3-bit Ripple Counter from Toggle Flip-FlopsEasy
  • D Latch from a 2:1 MUXEasy
  • 2-bit Ring CounterEasy
  • T Flip-Flop from a D Flip-FlopEasy
  • Handshake Deadlock Due to Early ResetHard
  • Reconvergence of Individually Synchronized BitsHard
  • Debug: Asynchronous Clear GlitchHard
  • Clock Gate Enable Crossing DomainsHard

Browse all problems · Learning tracks