CS 452/652 Winter 2026 - Lecture 22

TC2 Debrief, Recap

Mar 26, 2026 prev

TC2 Debrief

• Demo Mindset!
  1. smooth initialization/startup important for demo
     • run init sequence, turn on lights (and pay attention)!
     • have default entry locations for trains
     • re-init single train when lost
  2. train tracking / sensor attribution
     • recovery from deadspots - use lower- and upper-bound timer
  3. simple collision detection & avoidance
  4. path reservation, turnout switching
     • in-path reverse needs very good velocity estimation
     • also problematic with deadspots
  5. routing, path finding
  6. application: toot when trains reaches significant location
• technical debt
  • kernel, debugging, UI
  • routing/reservation in lieu of simple collisin detection?
• modularity

Recap

Hardware

• Raspberry Pi 4, Broadcom 2711, ARMv8, Cortex A72
• memory model, assembly, device access (timer, UART)
• serial communication
• CAN bus communication
• system registers, interrupt controller, exception vectors
• memory & CPU caches

Real-world Components

• Märklin tracks & trains
• control interface & quirks
• velocity and acceleration models
• failures

Systems Software

• cross compilation, linking, loading, initialization
• freestanding runtime environment
• slab allocation, free list, intrusive linkage
• ABI details
• concurrency and race conditions
• data representation

Operating System

• polling loop vs. task scheduling
• context switching: system call vs. interrupts
• scheduling, priorities, idle
• send-receive-reply message passing

Software Development

• sizable software system
• full control and responsibility
• challenging development environment
• optimization
• performance & measurements
• experimentation

Software Design & Control

• server & worker patterns
• layered control components
• domain-specific design

Theory

• latency analysis
• priority inversion
• scheduling & admission control