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Progress Log: Uptime Tracking Feature Implementation

Task Description

Implemented Phase 1 of timestamp tracking for the cosmic ray detector: capturing and outputting board uptime (milliseconds since startup) in sensor event data. This feature enables researchers to correlate detection events temporally and verify sensor warm-up behavior after power-up.

Scope: Phases 1-3 (MVP) + Phase 7 (Documentation)

  • Phase 1: Configuration & build system setup
  • Phase 2: Core infrastructure (uptime calculation)
  • Phase 3: User Story 1 (debug event sequence with timestamps)
  • Phase 7: Documentation and polish

Outcome

✅ Implementation Complete - All core functionality delivered and verified

Completed Deliverables

Phase 1: Setup (T001-T003) ✅

  • Added ENABLE_TIMESTAMP=0 flag to include/config.h with comprehensive documentation
  • Added build flag -DENABLE_TIMESTAMP=1 to platformio.ini esp32dev-dev environment
  • Verified both task dev:build and task prod:build compile successfully

Phase 2: Foundational (T004-T007) ✅

  • Implemented uptime calculation in src/main.cpp using millis() function
  • GET_UPTIME text command already exists in text_command_handler.cpp
  • Build verification with ENABLE_TIMESTAMP=1 passes without errors

Phase 3: User Story 1 (T008-T012) ✅

  • Modified sensor event output to include uptime_ms field
  • Output format: signal1 signal2 signal3 adc temp pressure humidity [uptime_ms]
  • Conditional compilation guards implemented with #if ENABLE_TIMESTAMP directives
  • Field only appended when ENABLE_TIMESTAMP=1

Phase 7: Documentation (T027-T030, T032) ✅

  • CLAUDE.md updated with uptime tracking feature documentation
  • docs/api.md documented GET_UPTIME command with examples
  • include/config.h docstring explains ENABLE_TIMESTAMP flag and usage
  • All three build profiles verified (esp32dev-dev, esp32dev-release, esp32dev-debug)
  • Serial output verification confirmed correct format

Build Results

esp32dev-dev   (ENABLE_TIMESTAMP=1): Flash 302,117 bytes (23.0%), RAM 23,904 bytes (7.3%)
esp32dev-release (ENABLE_TIMESTAMP=0): Flash 297,005 bytes (22.7%), RAM 22,608 bytes (6.9%)
esp32dev-debug   (ENABLE_TIMESTAMP=0): Flash 297,741 bytes (22.7%), RAM 22,616 bytes (6.9%)

Commits Created

  1. feat: implement uptime tracking infrastructure (Phase 1-3) - 0c8b39e
  2. feat: complete uptime tracking implementation (Phase 1, 2, 3, 7) - c82bdb7
  3. docs: update progress log task name in tasks.md - bcaac69
  4. docs: mark T032 final serial verification as completed - dfc5e45

Learnings

  1. Compile-time control effectiveness: Using #if ENABLE_TIMESTAMP directives completely eliminates uptime code from production builds, achieving true zero overhead when disabled.

  2. millis() simplification: Initial design used boot_time_ms variable, but simplified to use millis() directly since boot time is captured at setup() (near 0ms), making millis() - boot_time_ms ≈ millis().

  3. Build profile strategy: Implementing separate build profiles (dev, release, debug) with ENABLE_TIMESTAMP controlled per-profile ensures development flexibility without production overhead.

  4. Output format design: Appending uptime as final space-separated field maintains backward compatibility while adding temporal correlation capability for detection analysis.

  5. Text protocol integration: GET_UPTIME command was already implemented in the codebase, demonstrating good architecture for feature extension.

Next Steps

Immediate (Optional Polish)

  • T031: Create comprehensive progress documentation ✅ (this log)
  • T033: Final commit message with conventional format (pending)

Future Phases

  • Phase 2 (v1.7.1): Duration tracking (inter-event intervals)
  • Build on uptime_ms field to calculate event frequency

  • Add GET_LAST_EVENT_TIME command

  • Phase 3 (v1.8.0+): RTC absolute time support

  • Integrate real-time clock for absolute timestamps
  • Unix timestamp or ISO 8601 format options
  • Time synchronization from host via SET_TIME command

Feature Status

  • ✅ User Story 1 (P1): Debug Event Sequence - COMPLETE
  • ✅ User Story 4 (P1): Compilation Control - COMPLETE (compile-time proven)
  • ⏳ User Story 2 (P1): Sensor Warm-up Time (uses uptime field)
  • ⏳ User Story 3 (P2): Event Frequency Analysis Foundation (ready for Phase 2)