STM32

 STM 32 Development Board and applications

STM32 is a 32-bit microcontroller and microprocessor integrated circuit, manufactured by

STMicroelectronics. It is commonly used for evaluation, learning, prototyping, and product

development. It has multiple key features and typical applications. STM32 boards are based on the STM32 family of 32-bit ARM microcontrollers from STMicroelectronics.

STM32 Family

STMicroelectronics has introduced microcontrollers Cortex-M0, Cortex-M0+, Cortex-

M3, etc. and microcompressors MP1, MP2 series. Each STM32 microcontroller is

designed for specific performance, power efficiency, and feature requirements.

So we can make them suitable for a wide range of embedded application

STM32 boards come in  many variants because STMicroelectronics and third party  makers support a wide rangeof MCU families.

Official figures include:

ST Nucleo boards:

Over 70 variations across Nucleo-32, Nucleo-64, and Nucleo-144 formats. Nucleoboards are

affordable prototyping boards designed to help you get started with STM32 microcontrollers.

They support many STM32 variants and are great for general embedded projects where you

design your own circuits or add external modules.

Key Features: 

Integrated ST-LINK debugger/programmer: No external hardware required.
Arduino compatibility: Most have Arduino headers (Nano or Uno), so you can use shields.
ST Morpho headers: Expose full I/O for complex connections.
Support for popular IDEs: STM32CubeIDE, Keil, IAR, Mbed, GCC.
Multiple sizes: Nucleo-32, Nucleo-64, Nucleo-144 (refers to the number of MCU pins).
Ideal For:Learning STM32 basics, prototyping custom hardware, projects needingflexible I/O.

Discovery boards:

Many different Discovery kits exist (with sensors, displays, etc.). While there’s no exact

Discovery boards have onboard peripherals like sensors, displays, audio interfaces, and more.

They’re excellent for exploring what specific STM32 chips can do with real peripheral

examples. count published, dozens have been released over time, covering different MCU

series.

Key Features:

It has an Integrated ST-LINK debugger/programmer built-in function. Having onboard

sensors (e.g., gyros, accelerometers), LCDs, touch , or wireless modules, depending on

model. It's very useful for small projects for hobbyists.

STM32F429 Discovery:

(Cortex-M4F, color TFT display) 

The discovery board is very useful for interactive demos, signal processing, and graphicsapplications. STM32L4 Discovery IoT kits – low-power + wireless.

Ideal For: Learning peripherals, demos, interactive UI, sensor fusion, wireless IoT.

STM32 Eval Boards -

Full Feature Reference Platforms:

Eval (evaluation) boards are designed as reference designs. They expose almostall MCU pins and include external transceivers, sensors, memory interfaces, and more.

They offer the closest experience to real product hardware.

Key Features:

Complete hardware setups showcasing full STM32 capabilities. Suitable for complex

applications needing advanced connectivity or performance. Often more expensive and less

“plug-and play” than Discovery or Nucleo boards.

Ideal For:Product prototyping, performance evaluation, and advanced embedded design.

Community & Third-Party Boards:

Hundreds of low-cost “core boards” exist on global marketplaces (e.g., Alibaba/Amazon)

with different MCUs and feature sets. While not official ST boards, there are many popular

STM32-based boards from the community:

Blue Pill Low-cost board (e.g., STM32F103) with Arduino–style headers - great for
breadboarding. 

Black Pill – Similar but typically with faster MCUs (e.g., STM32F401).

Note: Always verify authenticity- some cheap boards use cloned chips.

Comparison of STM32 Boards

Board Type	Best Use For	Key Strength
Nucleo	Prototyping & learning	Flexible I/O, Arduino shield support
Discovery	Peripheral demos	On-board sensors/displays
Eval	Full evaluation	Complete hardware reference
Community boards	Affordable experiments	Basic functionality at low cost

Most Popular STM32 Boards (Based on Projects & Sales):

Popularity depends on the project type (learning vs advanced prototyping),but some clear favorites emerge based on sales data and community trends:

Top Popular / Best-Selling Models:

These boards show up most often on marketplaces and hobbyist purchases:

STM32F103C8T6 core board (“Blue Pill”)

Extremely cheap and widely available - great for basic MCU tasks and learning.

STM32F407VET6 / F407 Discovery

Powerful Cortex-M4 board with lots of peripherals - popular in embedded projects.

NUCLEO-F103RB (ST Nucleo)

Easy prototyping + Arduino shields + built-in ST-LINK debugger.

NUCLEO-F446RE / similar Nucleo boards:

Balanced performance and ecosystem support - widely used in learning and projects.

The STM32F103C8T6 board appears consistently as best-selling/hot-selling on marketplaces (For hobbyist and industrial applications).

Most Famous or Widely Used According to Project Type:

Learning & Beginner Projects:

STM32 Nucleo boards (e.g., NUCLEO-F103RB, NUCLEO-F401RE)

are very easy to start for many projects, have a built-in ST-LINK debugger, having a lot of

examples.

STM32F103C8T6 minimum board (Blue Pill):

It is very cheap and the same as an Arduino because it looks like an Arduino board.

Recommended for: basic embedded learning, GPIO/I2C/SPI timers, PWM, small

robotics, LED/sensor interfacing.

Intermediate / Advanced Projects:

Discovery boards (e.g., F407, F429, H7 series)

Onboard features like displays, sensors, USB, etc.

High-performance Nucleo (e.g., NUCLEO-H743ZI2)Great for DSP, RTOS, heavy interfaces.

Recommended for: RTOS systems, advanced peripheral control, graphics, audio processing,
and complex communication protocols.

Most Beginner-Friendly (Easy to Start):

Official ST Nucleo boards – built-in ST-LINK debugger means the easiest setup.

Boards with Arduino-style headers also make breadboarding easy.

Typically, prices start at ~$10–$20 for official boards.

I

Tips for Choosing:

Just learning MCU basics? → Start with a NUCLEO board with ST-LINK built in.
Want the lowest price per unit? → Go for cheap STM32F103/STM32F401 core boards.
Advanced/peripheral-heavy project? →Discovery kits or high-performance Nucleo boards.

STM32 Programming Methods:

To program STM32 development boards, you need:

1. Firmware libraries (what runs on the MCU)
   

2. Development software / IDE (where you write code)
   

3. Programmer/debugger tools
   

4. Programming languages

Below is a clear breakdown regarding software and integrated development environments.

1. Firmware & Software Frameworks (Libraries)

These are provided mainly by STMicroelectronics.

 STM32 Cube Ecosystem (Most Used Today)

STM32 CubeMX:

Graphical configuration tool
Configure GPIO, I2C, SPI, ADC, USB, CAN, etc.
Generates initialization code
Saves huge setup time

STM32 HAL (Hardware Abstraction Layer):

High-level driver library
Easier for beginners
Slightly slower than low-level drivers

LL (Low Layer) Drivers:

Faster and more optimized
Closer to hardware registers
Preferred for performance-critical applications

Middleware (Optional Add-ons):

Available through STM32Cube:

• FreeRTOS (Real-time OS)
  

• USB Device/Host stack
  

• TCP/IP (LWIP)
  

• FATFS (SD card)
  

• TouchGFX (GUI framework)
  

• Bluetooth / LoRa / WiFi stacks (depending on board)

2. Software / IDEs Used to Program STM32

Most Popular (Official & Free)

STM32CubeIDE

• Official IDE from ST
  

• Based on Eclipse + GCC
  

• Integrated CubeMX + Debugger
  

• Free
  

• Most recommended for beginners

 Professional IDEs:

Keil MDK

• Very popular in the industry
  

• Excellent debugger
  

• Free limited version (code size limit)
  

• Paid for the full version

IAR Embedded Workbench:

• Highly optimized compiler
  

• Used in professional embedded systems
  

• Paid license (trial available)

Open-Source Options:

PlatformIO

• Works inside VS Code
  

• Supports STM32 + Arduino + ESP32
  

• Very popular with makers

VS Code + GCC + OpenOCD:

• Fully customizable
  

• Advanced users

3. Programmer / Debugger Tools

Most official boards include a built-in debugger:

ST-LINK

• Built into Nucleo & Discovery boards
  

• Programs via SWD
  

• Supports debugging

If using cheap boards (e.g., Blue Pill), you may need:

• External ST-LINK
  

• USB-to-Serial (for UART flashing)

4. Programming Languages Used:

C (Most Common)

• Main language for STM32
  

• Fast, efficient
  

• Used with HAL/LL libraries
  

• Industry standard

C++

• Used in advanced applications
  

• Supported by STM32CubeIDE
  

• Used with RTOS or OOP designs

MicroPython

• Python for microcontrollers
  

• Easy for beginners
  

• Slower than C
  

• Not supported on all STM32 chips

Arduino (C++ Based)

• Some STM32 boards support the Arduino core
  

• Easier for hobby projects

Assembly

• Rarely used
  

• Only for ultra-critical optimization

What Is Most Used?

Categorys
IDE:
Language	Cb
Firmware Library	HAL
Debugger	ST-LINK
RTOS	FreeRTOSWha

• C language
  

• HAL or LL
  

• Keil / IAR
  

• Often with FreeRTOS

Beginner Recommendation:

If you're starting:

1. Install STM32CubeIDE
   

2. Use HAL drivers
   

3. Start with the C language
   

4. Use a Nucleo board (built-in ST-LINK)

Simple STM32 LED Blink Program:

Let’s start with a simple STM32 LED Blink example in C using:

• STM32CubeIDE
  

• HAL library
  

• Any STM32 board (example: Nucleo or Blue Pill)

I’ll show:

1. CubeMX configuration idea
   

2. Full main.c example
   

3. Explanation

Example: LED Blink Using HAL (C Language)

 Assumption

• LED connected to GPIO Pin PA5
  (On many Nucleo boards, PA5 is connected to the onboard LED.)

Step 1 – CubeMX Configuration:

Inside STM32CubeIDE:

1. Create a new STM32 project
   

2. Select your MCU or board
   

3. In Pinout view:
   

• Set PA5 → GPIO_Output
  

4. Go to Clock Configuration → leave default
   

5. Generate code

CubeMX will create initialization code automatically.

Step 2 – main.c Code (LED Blink):

Below is the important part inside while(1):

#include "main.h"

int main(void)

{

  HAL_Init();                 // Initialize HAL library

  SystemClock_Config();       // Configure system clock

  MX_GPIO_Init();             // Initialize GPIO

  while (1)

  {

    HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);  // Toggle LED

    HAL_Delay(500);                         // 500ms delay

  }

}

What Each Line Does:

Code	Meaning
HAL_Init()	Initializes HAL library
SystemClock_Config()	Sets CPU clock
MX_GPIO_Init()	Configures PA5 as output
HAL_GPIO_TogglePin()	Changes the LED state
HAL_Delay(500)	Wait 500 milliseconds

What Happens?

• LED ON → 0.5 sec
  

• LED OFF → 0.5 sec
  

• Repeats forever
  

Blink frequency = 1 Hz

What CubeMX Generates for GPIO:

Inside gpio.c:

GPIO_InitTypeDef GPIO_InitStruct = {0};

__HAL_RCC_GPIOA_CLK_ENABLE();

GPIO_InitStruct.Pin = GPIO_PIN_5;

GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

GPIO_InitStruct.Pull = GPIO_NOPULL;

GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

This sets:

• Output mode
  

• Push-pull
  

• No pull-up/down
  

• Low speed

If You Are Using Blue Pill (STM32F103)

Usually LED is on:

• PC13

So change this:

HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);

How To Flash Program

If using:

• Nucleo / Discovery → Built-in ST-LINK
  

• Cheap board → External ST-LINK

Steps:

1. Connect USB
   

2. Click Run → Debug
   

3. Code uploads automatically

FreeRTOS LED Blink Task

 Let’s move to a FreeRTOS LED Blink Task example on STM32.

We’ll use:

• C language
  

• HAL drivers
  

• FreeRTOS (via STM32CubeIDE)
  

• Any STM32 board (example: Nucleo with LED on PA5)

What is FreeRTOS?

FreeRTOS is a small Real-Time Operating System used in embedded systems.

Instead of:

                    while(1) { }

You create tasks (threads) that run independently.

Step 1 – Enable FreeRTOS in STM32CubeIDE:

• Create a new STM32 project

• Open .ioc file

• Go to:

Middleware → FreeRTOS → Enabled

• Leave default settings

• Set:PA5 → GPIO_Output

• Generate code

CubeIDE automatically includes FreeRTOS files.

Step 2 – Create LED Task

Inside freertos.c, add:

void StartLedTask(void *argument)

{

  for(;;)

  {

    HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);

    osDelay(500);   // 500ms delay (RTOS safe delay)

  }

}

Step 3 – Create the Task in Initialization:

In MX_FREERTOS_Init():

osThreadId_t ledTaskHandle;

const osThreadAttr_t ledTask_attributes = {

  .name = "ledTask",

  .stack_size = 128 * 4,

  .priority = (osPriority_t) osPriorityNormal,

};

ledTaskHandle = osThreadNew(StartLedTask, NULL, &ledTask_attributes);

CubeMX can also generate this automatically if you create a new task in the GUI.

 What Happens Now?

Instead of:

             HAL_Delay(500);

We use:

            osDelay(500);

Why?

HAL_Delay	osDelay
Blocks CPU	Allows other tasks to run
Not RTOS-friendly	RTOS aware

How It Runs Internally:

After main() initializes everything:

osKernelStart();

FreeRTOS scheduler starts.

From then:

• LED Task runs
  

• CPU switches between tasks automatically
  

• You can add more tasks easily

Example: Two Tasks (Better Demo)

void StartLedTask(void *argument)

{

  for(;;)

  {

    HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);

    osDelay(500);

  }

}

void StartPrintTask(void *argument)

{

  for(;;)

  {

    printf("Hello from FreeRTOS!\r\n");

    osDelay(1000);

  }

}

Now:

• LED blinks every 500ms
  
  

• UART prints every 1 second
  
  

• Both run independently

Why Use FreeRTOS?

✔ Multitasking

✔ Real-time scheduling

✔ Task priorities

✔ Semaphores & mutex

✔ Queues for communication

✔ Industry standard

Where It’s Used

• Industrial automation

• IoT devices

• Motor control

• Robotics

• Medical devices

When Should YOU Use FreeRTOS?

Use it if:

• You have 3+ independent modules
  

• Need communication between tasks
  

• Want a professional embedded design

Don’t use it if:

• Only blinking LED
  

• Very small MCU (low RAM)
  

• Ultra simple project