Project 20: Hardware Expansion Lab (Grove, GPS, LoRa, External ADC, Enclosure)

Build a modular hardware expansion platform for Cardputer with validated electrical budgets, stable bus coexistence, and enclosure-aware reliability.

Quick Reference

Attribute Value
Difficulty Expert
Time Estimate 2-3 weeks
Main Programming Language C
Alternative Programming Languages C++, Rust
Coolness Level Level 5
Business Potential Level 4
Prerequisites I2C/SPI/UART familiarity, hardware bring-up basics
Key Topics Grove architecture, GPS/LoRa integration, ADC quality, enclosure constraints

1. Learning Objectives

  1. Integrate multiple external modules without bus or power instability.
  2. Build module detection and graceful degradation behavior.
  3. Validate signal quality and thermal behavior in enclosure context.
  4. Document a reusable expansion compatibility matrix.

2. Theory

2.1 Expansion Interface Discipline

External modules are system-level changes; interface, power, and timing contracts must be explicit.

2.2 Mechanical-Electrical Coupling

Enclosure decisions affect thermal headroom, connector reliability, and long-run behavior.

3. Specification

  • Integrate GPS, LoRa, and external ADC modules.
  • Build power budget and address map.
  • Validate enclosure thermal profile.

Output:

I expand: gps fix=3D sats=9
I expand: lora link up rssi=-91
I expand: ext_adc noise_rms=0.8LSB
I expand: peak_current=412mA within_limit=yes

4. Architecture

[Module Registry] -> [Bus Manager] -> [Driver Adapters]
                                   -> [Power Supervisor]
                                   -> [Thermal/Health Monitor]

5. Implementation Guide

Core question:

“How do I add advanced hardware features without sacrificing system stability?”

Design questions:

  1. Which module combinations are officially supported?
  2. How do you isolate faulting modules at runtime?
  3. What enclosure constraints affect RF and heat most?

6. Testing

  • One-by-one module bring-up.
  • Combined-load stress test.
  • Thermal soak in enclosure.

7. Pitfalls

  • Address collisions and pull-up mismatch on I2C.
  • Power rail droop under module bursts.
  • Underestimating connector strain and vibration effects.

8. Extensions

  • Custom add-on PCB with integrated module mux.
  • Environmental sealing tradeoff study.

9. Completion

  • Multi-module integration runs stably.
  • Power/thermal budgets are measured.
  • Compatibility matrix and failure playbook exist.