Traffic Light 04 — Auto-Cycling Both Directions

Briefing

Double the Stage-3 pattern and wire it to loop: North-South cycles green->yellow->red, then East-West gets its turn, then back to North-South, forever. This is everything the capstone does except the all-red safety clearance between direction changes — that nuance is Stage 5's whole point.

Objectives

• North-South cycles green (3s) -> yellow (1s) -> red
• Then East-West cycles green (3s) -> yellow (1s) -> red
• Then back to North-South — the cycle repeats forever
• NS_GRN and EW_GRN are never true at the same time

I/O Table

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

1. #1NS and EW alternate, and the cycle repeats

   NS green, then EW green, then NS green again one full cycle later

2. #2NS and EW are never both green

   Safety check at each phase checkpoint across a full cycle