STM32F446RE — Firmware Development using FreeRTOS

This repository documents my hands-on projects with the STM32F446RE Nucleo Board, progressing from bare-metal GPIO programming to real-time operating system concepts using FreeRTOS, STM32CubeIDE and STM32CubeMX.

Each folder represents a standalone project focused on a specific peripheral, concept, or RTOS feature of the STM32 microcontroller.

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Topics Covered

• GPIO Digital Output & LED Control
• Digital Input with Push Buttons
• Ultrasonic Sensor Interfacing (HC-SR04)
• PWM Signal Generation & Duty Cycle Control
• Super Loop Architecture & Timing Counters
• FreeRTOS Task Creation & Scheduling
• FreeRTOS Task Priorities & Preemption
• External Interrupts (EXTI) with RTOS Synchronization
• Inter-Task Communication using Queues
• Shared Resource Management with Counting Semaphores

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Project Structure

Folder	Experiment	Description
01_GPIO_LED_Blink_SoftwareDelay	GPIO Digital Output — LED Blink	Configure a GPIO pin as digital output and verify LED blinking using software delay routines
02_PushButton_LED_Toggle	Digital Input — Push Button LED Toggle	Interface a push button as digital input and toggle LED state on each valid button press
03_HCSR04_Ultrasonic_LED_RangeIndicator	HC-SR04 Ultrasonic Sensor — Distance Classification	Interface the HC-SR04 ultrasonic sensor with STM32F446RE and classify distance ranges using LED visual indication
04_PWM_LED_BrightnessControl	PWM Generation — LED Brightness Control	Generate a PWM signal using a timer and control onboard LED brightness by varying the duty cycle
05_SuperLoop_LED_Button_Sensor	Super Loop Architecture — Multi-Peripheral Polling	Implement a super loop-based embedded program that sequentially handles LED blinking, button reading, and sensor acquisition using timing counters
06_FreeRTOS_SingleTask_LED_Blink	FreeRTOS Basics — Single Task LED Blink	Develop a basic FreeRTOS project in STM32CubeIDE and validate LED blinking using a single RTOS task
07_FreeRTOS_DualTask_Priority_LED	FreeRTOS Task Priorities — Dual Task Analysis	Create and execute two FreeRTOS tasks with different priorities and analyze their effect on LED blinking behavior
08_FreeRTOS_EXTI_Semaphore_LED	FreeRTOS Synchronization — EXTI + Binary Semaphore	Configure an external interrupt (EXTI) for a user button and use a binary semaphore to synchronize an LED control task
09_FreeRTOS_Queue_Sensor_UART	FreeRTOS Inter-Task Communication — Queue + UART	Implement inter-task communication using a FreeRTOS queue where one task acquires sensor data and another transmits it over UART
10_FreeRTOS_CountingSemaphore_SharedResource	FreeRTOS Resource Management — Counting Semaphore	Model a limited shared resource using a FreeRTOS counting semaphore and study access control when multiple tasks request the resource simultaneously

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Development Environment

Tool	Details
Board	STM32F446RE Nucleo
IDE	STM32CubeIDE
RTOS	FreeRTOS (via STM32Cube middleware)
Language	C
Flashing	STM32CubeIDE built-in / STM32CubeProgrammer

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Experiment Progression

GPIO Output → Button Input → Ultrasonic Sensor → PWM
       ↓
   Super Loop (Bare-Metal Multi-Peripheral)
       ↓
FreeRTOS Single Task → Dual Task Priorities → EXTI + Semaphore
       ↓
   Queue-based Sensor→UART Pipeline → Counting Semaphore

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Notes

• Experiments 1–5 follow a bare-metal / HAL-based approach with polling and software delays.
• Experiments 6–10 progressively introduce FreeRTOS concepts, building on each other.
• Each folder contains the full STM32CubeIDE project with source code and configuration files.
• This repository serves as a personal learning reference for embedded systems and RTOS programming.

Contributions, suggestions, and improvements are welcome!