Project 16: Real-Time Embedded Simulator

A simulated embedded system with interrupt handling, state machines, fixed-point math, and memory-constrained design patterns.

Quick Reference

Attribute Value
Primary Language C
Alternative Languages None
Difficulty Level 5 - Master
Time Estimate See main guide
Knowledge Area Embedded Systems, Real-Time Programming
Tooling GCC, QEMU (optional), Logic analyzer
Prerequisites See main guide

What You Will Build

A simulated embedded system with interrupt handling, state machines, fixed-point math, and memory-constrained design patterns.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Resource constraints → Maps to working without dynamic allocation
  • Real-time requirements → Maps to predictable timing
  • Hardware abstraction → Maps to simulating hardware interfaces

Key Concepts

  • Map the project to core concepts before you code.

Real-World Outcome

# 1. Run embedded simulator
$ ./embedded_sim
Embedded System Simulator v1.0
  CPU: Simulated 16MHz
  RAM: 4KB (stack: 1KB, heap: 0KB)
  Peripherals: Timer, GPIO, UART

Boot sequence:
  [0.000 ms] Hardware init... OK
  [0.012 ms] Calibration... OK
  [0.025 ms] Scheduler start... OK

Running tasks:
  [T+0.100 ms] sensor_read() - value: 2048 (raw), 25.3°C (calibrated)
  [T+0.200 ms] led_update() - LED: ON
  [T+1.000 ms] uart_transmit() - "TEMP:25.3\r\n"
  [T+1.100 ms] sensor_read() - value: 2052 (raw), 25.4°C (calibrated)

Interrupt log:
  [T+0.050 ms] TIMER_IRQ - tick
  [T+0.100 ms] TIMER_IRQ - tick
  ...

# 2. Fixed-point math demo
$ ./embedded_sim fixed_point
Fixed-Point Math (Q16.16):
  3.14159 represented as: 0x0003243F
  Multiply: 3.14159 * 2.0 = 6.28318
  Divide: 3.14159 / 2.0 = 1.57079
  Sin(PI/4) = 0.70711 (error: 0.00001)

# 3. Memory analysis
$ ./embedded_sim memory
Static memory usage:
  .text (code):  2,341 bytes
  .rodata:       128 bytes
  .data:         64 bytes
  .bss:          256 bytes
  Total Flash:   2,533 bytes
  Total RAM:     320 bytes (8% of 4KB)

Stack high-water mark: 412 bytes
No heap used (embedded safe!)

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: PROFESSIONAL_C_PROGRAMMING_MASTERY.md
  • Making Embedded Systems by Elecia White