STM32L475, bare metal, FreeRTOS portfolio

📂 Knowledge Base Roadmap

1. Phase 1: Bare-Metal SDK
   • From Silicon Handshake to Interrupt-Driven Bluetooth.
2. Phase 2: Building custom Schedulers
   • Context Switching, Priority Inversion, and SMP concepts.
3. Phase 3: Building a FreeRTOS application on STM32L475 from Scratch
   • Building a FreeRTOS application on STM32L475 (B-L475E-IOT01A) from Scratch without using IDE.
4. Phase 4: Modern C++ Transition & RTOS Architecture

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🚀 Engineering Modules

Phase 1. Bare_Metal architecture (Cortex M4)

• 01. Silicon Handshake - Bootstrapping, GPIO, and Modular Makefiles.
• 02. Precision Timing - SysTick Hardware, ISRs, and volatile memory safety.
• 03. Serial Communication - UART Peripheral and Clock Trees.
• 04. Environmental Sensing - I2C, Hardware FPU, and Sensor Interpolation.
• 05. DMA Acceleration - DMA Controller , DMA1_CH4, IRQ Handlers, Background Telemetry, and CPU Offloading.
• 06. Independant Watchdog - System Reliability IWDG, LSI Clocking, Fail-safe mechanisms.
• 07. SPI Bluetooth Hello - High-Speed Serial, Full-duplex SPI, FIFO management, Reset sequencing.
• 08. External Interupt via User Button - Verified EXTI/NVIC pipeline & VTOR.

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Phase 2: Building custom Schedulers

• 01. Preemptive Round-Robin Scheduler - context switching, pendSV Handler, Assembly code, time sliced preemption, Round-Robin, Real-Time kernel, and Modular Makefiles, .vscode launch.json for debugging.

• 02. Preemptive Priority-Based Scheduler - Priority preemption, state based scheduling, non-blocking delays, Idle task, High priority ready algorithm

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“Phase 3: Building a FreeRTOS application on STM32L475 from Scratch”

• 01.Guide to prepare project setup - FreeRTOS Kernel, STM32L4 ST library, prepare build system, run blinky.

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Phase 4: Modern C++ Transition & RTOS Architecture

• 01. Architectural Migration, Modern Build Systems and advanced Debugging & Reliability
  • C to C++17 transition, RAII, and Dependency Injection in RTOS.
  • Modular CMake architecture, Toolchain files, and automated size reporting.

  • Cortex-Debug, Watchdog Event Groups, and HW/SW state synchronization.

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🛠 Tech Stack

• Hardware: Discovery kit IoT node (B-L475E-IOT01A)
• Compiler: arm-none-eabi-gcc (Optimization: -O0 for debug clarity)
• Debugger: OpenOCD via ST-Link V2-1
• Operating environment Ubuntu on WSL
• IDE Microsoft Visual Studio Code

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Lesson learned

Everything that I learned - The references, the logic, the hurdles and outcomes during different phases of my excercise. Refer links below,

1. Bare-Metal Lesson Learned section.
2. Scheduelr Lesson Learned section.

Code Quality & Automation (applies to FreeRTOS project only)

To ensure the reliability of the FreeRTOS scheduler and application logic, this project uses an automated Code Quality & Automation so that every commit is audited before being deployed.

The comprehensive guide for setting up MISRA C, cppCheck and Lizard guide is here

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