📘 STM32 Smart Sensor Hub

A Modular, Power-Aware Firmware System with CLI Dashboard, Logging Framework, and Sensor Abstraction

Target MCU: STM32 Nucleo-F446RE
Toolchain: STM32CubeIDE / arm-none-eabi-gcc
UART Interface: ST-LINK VCP (typically USART2 @ 115200)

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🚀 Overview

The STM32 Smart Sensor Hub is a professionally structured embedded firmware project built to demonstrate modern firmware engineering practices:

• Modular layered architecture
• Cooperative task scheduler
• Runtime-configurable structured logging framework
• Interactive UART CLI (dashboard-style)
• Power management system
• Sensor abstraction (simulated sensor now, real sensors later)
• Dynamic sensor sampling period that adapts to the current power mode
• GitHub Actions CI (compile-only)
• Full documentation
• Clean, maintainable C code with Doxygen-ready comments

This repository is structured like a real production firmware codebase.

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🏗️ Architecture at a Glance

stm32-smart-sensor-hub/
├── Core/                     # Cube-generated startup, HAL, clock config
├── Drivers/                  # HAL drivers
├── app/                      # Application entry, task manager, main loop
├── common/                   # Logging framework, CLI, utilities
├── sensors/                  # Sensor abstraction + simulated sensor
├── power/                    # Power manager module
├── docs/                     # Documentation for all phases
└── .github/workflows/        # GitHub Actions CI

Layer Summary

Layer	Purpose
Core/	System startup, HAL initialization, ISR handlers
app/	Main application logic + cooperative task scheduler
common/	Logging subsystem, CLI interpreter, helpers
sensors/	Sensor interface API + simulated sensor backend
power/	Power mode manager (Active/Idle/Sleep/Stop)
docs/	Architecture docs, release notes
.github/	CI pipeline (ARM GCC build verification)

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🧩 Key Features

✔️ Cooperative Task Scheduler

Tasks include:

• Heartbeat
• SensorSample
• PowerManager
• CLI

Each task has its own period and logs its execution timing.

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✔️ Structured Logging Framework

Log format:

[00123456 ms][INF][../app/app_main.c:152][App_TaskSensorSample] Value=23.1 C

Supports:

• DEBUG / INFO / WARN / ERROR
• Runtime filter control
• CLI-controlled pause/resume
• Automatic CLI prompt redraw after each log line

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✔️ UART CLI Dashboard

Example commands:

help
log pause
log resume
log info
log debug
pmode idle
status

Features:

• Non-blocking input
• Backspace support
• Dashboard-style, always-visible prompt
• Logs never overwrite the CLI command entry line

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✔️ Sensor Abstraction Layer

typedef struct {
    bool (*init)(void);
    bool (*read)(SensorData_t *out);
} SensorIF_t;

Currently uses a simulated temperature sensor (sensor_sim_temp.c/.h)
plugged into this interface.

Later you can plug in:

• I²C sensor
• SPI sensor
• ADC sensor
• Additional simulated/virtual sensors for testing

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✔️ Power Management Framework + Dynamic Sampling

Power modes:

• POWER_MODE_ACTIVE
• POWER_MODE_IDLE
• POWER_MODE_SLEEP
• POWER_MODE_STOP

The SensorSample task period automatically adapts to the current power mode:

#define SENSOR_PERIOD_ACTIVE_MS   (1000U)   // 1 second in ACTIVE mode
#define SENSOR_PERIOD_IDLE_MS     (5000U)   // 5 seconds in IDLE mode
#define SENSOR_PERIOD_SLEEP_MS    (30000U)  // 30 seconds in SLEEP mode
#define SENSOR_PERIOD_STOP_MS     (0U)      // 0 => no sampling in STOP

• In STOP mode, sensor sampling is completely disabled.
• The CLI status command reports the effective sensor sample period.

This models how a real low-power system would adapt workload based on its power budget.

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✔️ GitHub Actions CI

• Installs ARM GCC
• Builds firmware on Ubuntu
• Verifies compilation on every push & PR

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🛠️ Build & Flash Instructions

1. Open the project in STM32CubeIDE.
2. Build the project (Debug or Release).
3. Flash the firmware to the Nucleo-F446RE.
4. Open a serial monitor at 115200 baud, 8N1.
5. Reset the board and look for the CLI banner.
6. Type help to see available commands.

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🖥️ Example CLI Session

Smart Sensor Hub CLI ready.
Type 'help' for commands.

> log info
[00001234 ms][INF][../app/app_main.c:129][App_TaskHeartbeat] Heartbeat task toggled LED
[00002234 ms][INF][../app/app_main.c:152][App_TaskSensorSample] SensorSample: value=23.10 C, timestamp=2234 ms

> pmode sleep
Requested power mode change: sleep

> status
Status:
  Task logging: ENABLED
  LogLevel: 1 (0=DEBUG,1=INFO,2=WARN,3=ERROR)
  PowerMode: 2 (0=ACTIVE,1=IDLE,2=SLEEP,3=STOP)
  Sensor sample period: 30000 ms

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📄 Documentation

Included in /docs:

• README.md (this file)
• ARCHITECTURE.md (layered design)
• RELEASE_NOTES.md (per-phase changes)
• CLI_COMMANDS.md (detailed CLI behavior and examples)

All are updated at each project phase.

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📌 Current Version: v0.4.0

Includes:

• CLI dashboard
• Logging framework enhancements
• Power Manager foundation
• Task Manager improvements
• Sensor abstraction and simulated sensor
• Dynamic sensor sampling based on power mode (ACTIVE/IDLE/SLEEP/STOP)
• GitHub workflow
• Full documentation

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🧭 Roadmap (Planned Phases)

• Phase 5 → Real I²C sensor integration
• Phase 6 → Real STM32 low-power mode entry/wakeup
• Phase 7 → Event/state machine on top of tasks
• Phase 8 → Flash/SD logging or host-side tooling
• Phase 9 → BLE or USB link to external dashboard
• Phase 10 → Remote telemetry / visualization

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💼 Resume Impact

This project demonstrates:

• Embedded architecture & modular design
• Reusable driver and sensor abstraction
• Task scheduling and power management
• Power-aware behavior (dynamic sensor sampling vs power mode)
• CLI protocol handling and UX considerations
• Logging frameworks with runtime control
• CI/CD discipline for embedded firmware

Ideal to showcase for Embedded/Firmware Engineer roles.

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📝 License

MIT